SP7350 Application Circuits

This document elucidates the application circuitry associated with the SP7350. It serves as a supplementary resource to the specification of the SP7350.

Table of Contents

1. RTC

The SP7350 comes equipped with a built-in real-time clock (RTC) module, strategically placed within an independent power domain. This module is designed to remain powered continuously by an external power source such as a battery or super capacitor. This ensures uninterrupted functionality, even when other power domains are deactivated.

1.1 Power Requirements

Operating on a mere 1.8 volts, the RTC module is notably efficient. Its internal Low Dropout Regulator (LDO) generates a 0.8-volt power supply specifically for the RTC digital core. Refer to the schematic below for recommended power pin configurations, which necessitate the inclusion of bypass capacitors on the VDDPST18_GPIO_RTC and VDD_RTC pins.

1.2 32.768kHz Crystal

To work with precision, the RTC module requires connection to a 32.768 kHz crystal, alongside phase-shift circuitry, as illustrated in the schematic provided.

1.3 Wake-up Key Detection

The RTC module also boasts wake-up key detection functionality. When the CM4_WAKEUP_KEY pin is maintained at a HIGH state for 1 second, the CM4_PWR_EN pin is automatically set to HIGH by internal logic, activating power to the CM4 power domain. Refer to the timing charts below for a visual representation of this process.

Furthermore, if the CM4_WAKEUP_KEY pin remains HIGH for over 10 seconds, CM4_PWR_EN is forcibly set to LOW, effectively powering down the CM4 power domain. This functionality is depicted in the accompanying timing chart.

In addition to its hardware capabilities, the CM4 software incorporates default functionality as outlined below:

Refer to the schematic below for an example circuitry setup. In this configuration, the CM4_WAKEUP_KEY pin is linked to a physical key. Pressing the key pulls the CM4_WAKEUP_KEY signal to HIGH, while its default state remains LOW.

1.4 RTC_1V8 Power Supply

The schematic below illustrates a sample RTC_1V8 power supply circuitry. Drawing power from a source ranging from 3V to 5V, the system employs a super capacitor to store and deliver power during VCC downtimes. Resistor R16 (470Ω) regulates the charge current. Finally, a 1.8V low quiescent current LDO efficiently converts VCC_RTC to the required 1.8V power (RTC_1V8) for the RTC module's operation.

2. CM4 System

The CM4 system is equipped with an ARM Cortex M4 microcontroller and an array of interfaces, including 10 channels of I2C, 6 channels of SPI, 4 channels of PWM, 6 channels of UART, and 3 channels of audio I2S. The pins associated with these peripherals can be programmed to connect to either dual voltage IO (DVIO) pins or general-purpose IO (GPIO) pins.

Operating within its own independent power domain, the CM4 system is designed to remain functional even when the main power domain (comprising the CPU, NPU, video codec, MIPI-TX, MIPI-RX, USB3, etc. ) is powered off. The primary objectives of the CM4 system are as follows:

• Control the power on and off sequences of the main power domain.

• Communicate with Linux, running in the main power domain, via mailbox to facilitate entry into and resumption from deep-sleep mode (suspend to RAM).

• Manage peripherals and IO operations of the CM4 system, including external devices control and communication with other devices or microcontrollers.

• Monitor external events, such as signals from remote controllers and human voice commands.

2.1 Power Requirements

The CM4 system requires four distinct power sources:

• 0.8V power for the digital core and system PLL (PLLS).

• 1.8V power for the ADC, GPIO, dual voltage IO (DVIO), and VDD1 of LPDDR4 SDRAM.

• 3.0V power for DVIO.

• 1.1V power for VDDQ and VDD2 of LPDDR4 SDRAM, or alternatively, 1.5/1.35V power for VDDQ of DDR3/3L SDRAM.

All power sources should be managed using the CM4_PWR_EN signal. Specifically, when CM4_PWR_EN is set to LOW, all power supplies, including those for the CM4 and Main power domain, should be deactivated.

Please refer to the provided power scheme for details on power control.

Refer to the schematic below for the recommended wiring of the 0.8V power supply for the digital core (VDD_AO) and system PLL (AVDD08_PLLS). It's crucial to include bypass capacitors to effectively filter high-frequency noise from the power supply lines. Additionally, for the AVDD08_PLLS power pin, it's recommended to use a ferrite bead on both the power and ground lines. This helps ensure precise operational frequency and minimizes clock jitter.

2.2 25MHz Crystal

The CM4 system needs a 25 MHz crystal accompanied by phase-shift circuitry, as depicted in the schematic below. This clock serves as the reference for various PLLs within the system, including PLLS (the system PLL), as well as PLLC, PLLL3, PLLD, PLLN, and PLLH, all located within the main power domain.

2.3 ADC

Featuring a four-channel, 12-bit analog-to-digital converter (ADC), the CM4 system requires a 1.8V power supply. It's recommended to incorporate a ferrite bead for power pin SAR12B_AVDD18 and separate grounding to filter out high-frequency noise, as depicted in the schematics.

2.4 DVIO (AO_MX0 ~ AO_MX29)

The DVIO pins are grouped into three categories, each with its own power supply and bias power pins. Consult the table provided for pin grouping details, ensuring appropriate connections with bypass capacitors.

The VDDPST18_DVIO_AO_x pins (where 'x' represents 1, 2, or 3) are designated for internal bias circuitry and necessitate connection to bypass capacitors. Simultaneously, the VDDPST3018_DVIO_AO_x pins (where 'x' represents 1, 2, or 3) require connection to a power supply of either 1.8V or 3.0V, supplemented by bypass capacitors.

2.5 GPIO, Bootstrap and RESET Pins

In addition to DVIO pins, the CM4 system includes a RESET pin, seven bootstrap pins, and nineteen GPIO pins. These pins are powered by two VDDPST18_GPIO_AO pins connected to a 1.8V power supply with bypass capacitors.

2.5.1 GPIO (AO_MX30 ~ AO_MX48)

These pins serve as 1.8V general-purpose IO (GPIO) pins and are prefixed with "AO_" indicating their association with the Always On (CM4) power domain. For ease of reference, consult the table below to determine the corresponding GPIO number for manipulation of IO registers.

2.5.2 Bootstrap Pins (IV_MX0 ~ IV_MX6)

The seven bootstrap pins encompass a variety of functions pertaining to boot device selection, CA555 JTAG interface activation, and chip test mode activation. Refer to the table below for the definition of each bootstrap pin regarding boot device selection:

(Note: "x" indicates "don't care" value)

When IV_MX2 is set to LOW, the SP7350 enters test mode, designated for internal use only. Likewise, when IV_MX1 is set to LOW, the CA55 JTAG interface pins are activated. IV_MX0 remains unused.

Following the de-assertion of the RESET pin, these pins can be repurposed as GPIOs. Refer to the table below for the corresponding GPIO numbers for IO registers manipulation.

2.5.3 Reset Circuitry

Pulling the RESET pin to LOW initiates a reset of the CM4 system, encompassing all components such as the Cortex M4, digital core, peripherals, DVIO, and GPIO pins. The schematic indicates the use of a voltage supervisor chip responsible for monitoring the 1.8V power supply.

The RESETB signal transitions to a deasserted state (HIGH) once the 1.8V power stabilizes and is ready for operation, a condition met after a typical duration of 107 milliseconds. Conversely, if the power supply fails to stabilize within this timeframe, the RESETB signal remains asserted (LOW), ensuring that the reset process is delayed until a stable power state is achieved.

2.5.4 Setup IO Voltage of Boot Device

The GPIO82 pin plays a crucial role in configuring the internal bias circuitry of DVIO pins utilized by boot devices. During the boot sequence execution, the i-boot (ROM code) reads the state of this pin to establish the bias circuitry of the DVIO pins associated with the boot device.

For systems utilizing a 1.8V IO boot device, it is necessary to connect the GPIO82 pin to GND through a 4.7 kΩ pull-down resistor. This configuration ensures proper setup of the bias circuitry for compatibility with the 1.8V IO boot device. Conversely, if employing a 3.3V IO boot device, it is essential to leave the GPIO82 pin open to maintain compatibility with the higher voltage requirement of the boot device.

3. Powers for Main System

The main system encompasses all components except for the RTC module and CM4 system. This includes the ARM Cortex A55, DDR SDRAM controller, NPU (VIP9000), video codec, GMAC, USB3, USB3, MIPI-RX, MIPI-TX, eMMC, SD card, SDIO and NAND flashes controller and etc.

Refer to the power scheme illustrated below. All powers in the main power domain should be controlled by both CM4_PWR_EN and MAIN_PWR_EN signals. Specifically, all powers in the main power domain are only turned on when both CM4_PWR_EN and MAIN_PWR_EN are set to HIGH.

It's important to note that during cold booting, CM4_PWR_EN goest to HIGH to initiate the booting process. Therefore, the default state of MAIN_PWR_EN (when the GPIO is not yet programmed) should be HIGH to allow the CA55 to start booting.

Typically, MAIN_PWR_EN is controlled by a GPIO in the CM4 domain. CM4 can directly set the power of the main power domain to either on or off.

3.1 Power Requirements for PLL, Thermal Sensor, and OTP Burning

Refer to the schematic below for the recommended power configuration. Provide a 0.8V power supply for PLLs (AVDD08_PLLC and AVDD08_PLLD) and a 1.8V power supply for the thermal sensor (TML_AVDD18) and OTP burning (OTP_1V8). Bypass capacitors are essential to filter out high-frequency noise from the power supply lines.

AVDD08_PLLC powers PLLC (the CPU PLL), PLLL3 (the CPU L3 cache PLL), PLLH (the peripheral PLL), and PLLN (the NPU PLL). Similarly, AVDD08_PLLD powers PLLD (the DRAM PLL). Both require ferrite beads on the power and ground lines for stability and reduced clock jitter.

3.2 Power Requirements for System, Video-Codec, CA55 and NPU

The recommended power wiring for VDD (system digital core), VDD_VV (video codec), VDD_CA55 (CPU CA55), and VDD_NPU (NPU) is detailed in the schematic below. Bypass capacitors are crucial to provide a low-impedance path to ground and reduce voltage ripple when high current is drawn.

Refer to the table below for the target impedance for each power domain, ensuring optimal performance:

Each power domain operates independently and can be powered on or off individually. Note that VDD powers the system digital core, including the AXI bus and top-level components. It should be powered on first, followed by CA55, NPU, and the video codec for proper functionality.

Additionally, the VDD_NPU_MEASURE signal, a subset of the VDD_NPU pin, serves the specific purpose of providing feedback on the VDD_NPU voltage to the DC2DC regulator for precise control.

4. GPIO and DVIO of Main System

The main system features 20 General Purpose IO (GPIO) pins and 18 Dual Voltage IO (DVIO) pins. GPIO operates at 1.8V, while DVIO offers the flexibility of operating at either 1.8V or 3.0V, accommodating various voltage requirements.

In addition to serving as IO pins, interface pins of devices within the CM4 system or main system can be configured to connect to GPIO or DVIO pins. This adaptability facilitates seamless integration, enhancing overall flexibility and functionality within the system architecture.

4.1 GPIO (G_MX0 ~ GMX19)

GPIO pins are powered by two VDDPST18_GPIO_0 and VDDPST18_GPIO_1 power pins, which should be connected to a 1.8V power supply with bypass capacitors for stable operation.

For ease of reference, consult the table below to determine the corresponding GPIO number for manipulation of IO registers:

Moreover, the G_MX2 (GPIO2) pin fulfills a specialized role in resetting peripherals by generating a 10-millisecond LOW pulse during system reboots. A dedicated driver is incorporated into GPIO2 to manage the PER_RESET (low-active) signal effectively. Refer to the following schematics for further details.

4.2 DVIO (G_MX20 ~ GMX37)

The DVIO pins are divided into two groups, each with its own power supply and bias power pins. Refer to the table provided for pin grouping details:

Ensure appropriate connections with bypass capacitors for stable operation. The VDDPST18_DVIO_x pins (where 'x' represents 1 or 2) are designated for internal bias circuitry, while the VDDPST3018_DVIO_x pins (where 'x' represents 1 or 2) require connection to a power supply of either 1.8V or 3.0V, supplemented by bypass capacitors.

Refer to the schematics for visual guidance.

5. DDR SDRAM

The DDR SDRAM controller of SP7350 support five types of DDR SDRAM: LPDDR4, DDR4, LPDDR3, DDR3, and DDR3L. The maximum support speed are:

Please note that only LPDDR4, DDR4, DDR3L and DDR3 are verified.

5.1 Data Bus and Data Strobe Signals Wiring

Refer to the table below for the wiring of data bus and data strobe signals for different types of DDR SDRAM.

5.2 Address Bus and Control Signals Wiring

The table below illustrates the wiring of address bus and control signals for various types of DDR SDRAM.

5.3 LPDDR4 Circuitry

5.3.1 DDR PHY of SP7350

Please refer to the schematics for the connection details of power, command address bus, data bus, and clocks of the DDR PHY.

• The DRAM_VDD power pins are designated for the digital core of the DDR PHY. It is essential to connect these pins to a 0.8V power source and include bypass capacitors for stable operation.

• The DRAM_VDDQ power pins cater to the IO buffers of the DDR PHY. These pins must be connected to a 1.1V power source and equipped with bypass capacitors to ensure optimal performance.

• The BP_VAA power pin serves the PLL of the DDR PHY. It is crucial to connect this pin to a 1.8V power source and include bypass capacitors to maintain stable PLL operation.

Refer to the table below for the operational range of each power source:

It is crucial to design the PCB to meet target impedance values for the DRAM_VDD, DRAM_VDDQ, and BP_VAA power pins. Refer to the table below for the target impedance values for each power source:

Adhering to these target impedance values ensures optimal performance and reliability of the DDR PHY within the PCB design.

5.3.2 CA and Data Signals of LPDDR4 SDRAM

Please refer to the schematics for the connection of power, control, address bus, and data bus of LPDDR4 SDRAM.

5.3.3 Power and Ground of LPDDR4 SDRAM

The VDD1 (1.8V), VDD2 (1.1V), and VDDQ (1.2V) power lines of LPDDR4 SDRAM require numerous bypass capacitors to enhance signal integrity by mitigating signal reflections and ringing on the power supply lines. Please refer to the schematics provided below for further details.

5.4 DDR4 Circuitry

5.4.1 DDR PHY of SP7350

Please refer to the schematics for the connection details of power, address bus, data bus, and control signals of the DDR PHY.

• The DRAM_VDD power pins are designated for the digital core of the DDR PHY. It is essential to connect these pins to a 0.8V power source and include bypass capacitors for stable operation.

• The DRAM_VDDQ power pins cater to the IO buffers of the DDR PHY. These pins must be connected to a 1.2V power source and equipped with bypass capacitors to ensure optimal performance.

• The BP_VAA power pin serves the PLL of the DDR PHY. It is crucial to connect this pin to a 1.8V power source and include bypass capacitors to maintain stable PLL operation.

Refer to the table below for the operational range of each power source:

It is crucial to design the PCB to meet target impedance values for the DRAM_VDD, DRAM_VDDQ, and BP_VAA power pins. Refer to the table below for the target impedance values for each power source:

Adhering to these target impedance values ensures optimal performance and reliability of the DDR PHY within the PCB design.

5.4.2 Address and Data Signals of DDR4 SDRAM

Please refer to the schematics for the connection of power, address bus, data bus, and control signals of the DDR PHY. Two DDR4 SDRAM chips are utilized to form a 32-bit width data bus. Besides, the T-topology methodology is employed to route the address signals from the PHY to the two SDRAM chips.

5.4.3 Clock Termination

Please refer to the schematics provided below. The clock signal differential pair of DDR4 SDRAM (DRAM_CLK0_T and DRAM_CLK0_C) requires AC termination with a differential impedance of 100Ω. Additionally, the T-topology methodology is employed to route the clock signals from the PHY to the two SDRAM chips.

5.4.4 SDP or DDP Selection

Please refer to the schematics provided below. Resistors Re9, Rm9, and Rm9b are utilized for configuring either the Single Die Package (SDP) or Dual Die Package (DDP) DDR4 SDRAM.

The table below offers a detailed configuration guide for SDP or DDP DDR4 SDRAM:

5.4.5 Bypass Capacitors for VDDQ Power of DDR4 SDRAM

The VDDQ power of DDR4 SDRAM requires numerous bypass capacitors to enhance signal integrity by mitigating signal reflections and ringing on power supply lines. Please refer to the schematics provided below for further details.

VPP1 and VPP2 power require bypass capacitors to effectively filter out high-frequency noise present in the power supply lines.

5.5 DDR3/DDR3L Circuitry

5.5.1 DDR PHY of SP7350

Please refer to the schematics for the connection details of power, address bus, data bus, control signals and clock of the DDR PHY.

• The DRAM_VDD power pins are designated for the digital core of the DDR PHY. It is essential to connect these pins to a 0.8V power source and include bypass capacitors for stable operation.

• The DRAM_VDDQ power pins cater to the IO buffers of the DDR PHY. These pins must be connected to a 1.35V power source for DDR3L (or a 1.5V power source for DDR3) and equipped with bypass capacitors to ensure optimal performance.

• The BP_VAA power pin serves the PLL of the DDR PHY. It is crucial to connect this pin to a 1.8V power source and include bypass capacitors to maintain stable PLL operation.

Refer to the table below for the operational range of each power source:

It is crucial to design the PCB to meet target impedance values for the DRAM_VDD, DRAM_VDDQ, and BP_VAA power pins. Refer to the table below for the target impedance values for each power source:

Adhering to these target impedance values ensures optimal performance and reliability of the DDR PHY within the PCB design.

5.5.2 Address and Data Signals of DDR3 SDRAM

Please refer to the schematics for the connection of power, address bus, data bus, and control signals of DDR3 SDRAM. Two DDR3 SDRAM chips are utilized to form a 32-bit width data bus. Besides, the T-topology methodology is employed to route the address signals from the PHY to the two SDRAM chips.

5.5.3 Clock Termination

Refer to schematics below, the differential-pair clock signal of DDR3 SDRAM (DRAM_CLK0_T and DRAM_CLK0_C) requires AC termination with a differential impedance of 100Ω. Furthermore, the T-topology methodology is utilized to route the clock signal from the PHY to the two SDRAM chips.

5.5.4 Bypass capacitors for VDD and VDDQ power of DDR3 SDRAM

The VDD and VDDQ power lines of DDR3 SDRAM require numerous bypass capacitors to enhance signal integrity by mitigating signal reflections and ringing on the power supply lines. Please refer to the schematics provided below for further details.

6. eMMC

The SP7350 supports booting from an eMMC device. To boot from the eMMC device, set the bootstrap pins IV_MX[6:2] to [1 1 1 1 1]. The default sector size of the eMMC is 512 bytes, and the maximum supported capacity is 128 GB. The device achieves a maximum speed of HS200 (SDR-200MHz) or DDR-133MHz when using a 1.8V IOVDD.

6.1 eMMC Interface of SP7350

The eMMC device's interface pins connect to GPIO20, GPIO28 ~ GPIO37, corresponding to D5, D3, D4, D0, D1, CLK, D2, D7, D6, CMD, and DS signals. GPIO37 is necessary only for HS400 mode.

The VDD_DVIO_2 power group, comprising GPIO20 and GPIO28 to GPIO37 pins, supports both 1.8V and 3.3V operations.

6.2 eMMC Chip

For eMMC chip wiring, refer to the provided schematics. Connect the VDD power pins of the eMMC chip to the power pins (VDD_DVIO_2) of GPIO20, GPIO28 to GPIO37. The VDDF power pins should be connected to a 3.3V power source. Make sure to connect all power pins to bypass capacitors. This ensures stable operation and improves signal integrity by minimizing signal reflections and ringing on the power supply lines.

The RSTN (device reset) pin connects to the peripheral reset signal, PER_RESETB, to trigger a reset during system reboots, ensuring the eMMC device boots successfully.

If the eMMC device isn't used, the interface pins can function as DVIO pins.

6.3 Pull-up Resistors

It's advisable to add 51 kΩ pull-up resistors for SDIO data and command signals by default.

7. SD Card

The SP7350 also supports SD cards for booting. The default sector size is 512 bytes, and the maximum capacity is 128 GB. To boot from an SD card, set the bootstrap pins IV_MX[6:2] to [1 1 0 0 1]. The maximum operation speed is SDR-200MHz (100MB/s).

7.1 SD Card Port of SP7350

Refer to the provided schematics for the detailed SD card interface and power connections. The SD card's interface pins connect to GPIO38 ~ GPIO43 for D1, D0, CLK, CMD, D3, and D2 signals. Supply the AVDD30_SD_SDIO power pin with 3.0V, using bypass capacitors for stability. VDDPST18_SD and VDDPST18IO_SD pins are for internal bias circuitry and should also connect to bypass capacitors.

If the SD card interface isn't used, the interface pins can function as DVIO pins.

7.2 Micro SD Card Socket

Refer to the schematics for micro SD card connections. SD card interface signals should follow the micro SD card socket's pin-out. The SD (VCC) pin requires a 3.3V power supply with bypass capacitors for stability. The SD_IN pin detects card insertion, connecting to a GPIO pin.

7.3 Pull-up Resistors

For SD card data and command signals, it's recommended to add 30kΩ pull-up resistors by default.

7.4 Power Control

The SD card's power is controlled by the peripheral reset signal, PER_RESETB. When PER_RESETB is asserted (LOW), the SD card power turns off and turns on when de-asserted. This circuitry helps recover the SD card from an unknown state, ensuring successful booting.

If the SD card isn't a boot device, this power control circuitry isn't necessary.

8. SDIO

The SP7350 supports an SDIO interface with a maximum operation speed of SDR-200MHz (100MB/s). Connect it to any SDIO interface device, such as an SDIO interface WiFi chip.

8.1 SDIO Port of SP7350

Refer to the provided schematics for detailed SDIO interface and power connections. The SDIO interface pins are multiplexed with GPIO44 ~ GPIO49 for D1, D0, CLK, CMD, D3, and D2 signals. The AVDD30_SD_SDIO power pin shares power with the SD card interface and requires a 3.0V supply with bypass capacitors for stability. VDDPST18_SDIO and VDDPST18IO_SDIO pins are for internal bias circuitry and should also connect to bypass capacitors.

If the SD card interface isn't used, the interface pins can function as DVIO pins.

8.2 Pull-up Resistors

For SDIO data and command signals, it's recommended to add 30kΩ pull-up resistors by default.

9. SPI-NOR Flash

The SP7350 supports SPI-NOR flash for booting. For booting from an SPI-NOR flash, configure the bootstrap pins IV_MX[6:2] to [1 0 1 1 1]. The SP7350 accommodates a maximum capacity of 64 MB for SPI-NOR flash and operates at up to 102 MHz when using a 1.8V SPI-NOR flash chip. It is recommended to use 1.8V flash chip for high speed operation.

9.1 SPI-NOR Interface of SP7350

The interface pins for the SPI-NOR flash connect to GPIO21 ~ GPIO26, corresponding to D2, CLK, D1, D3, CSB, and D0 signals.

The VDD_DVIO_1 power group, comprising GPIO21 to GPIO27 pins, supports both 1.8V and 3.3V operations.

9.2 SPI-NOR Flash Chip

For wiring the SPI-NOR flash, consult the provided schematics. Connect the VDD power pins of the SPI-NOR flash to the FLASH_SW power source derived from VDD_DVIO_1 power of GPIO21 to GPIO26. Ensure the power pin connect to bypass capacitors to maintain stable operation and enhance signal integrity by reducing signal reflections and ringing on the power supply lines. For D2, D3, and CSB signals, it's recommended to include 10kΩ pull-up resistors by default.

If the SPI-NOR flash interface isn't utilized, these pins can serve as DVIO pins.

9.3 Power Control

Power to the SPI-NOR flash is managed by the peripheral reset signal, PER_RESETB. When PER_RESETB is active (LOW), the SPI-NOR flash power is disabled, and it's enabled when the signal is inactive. This power control circuitry aids in recovering the SPI-NOR flash from an indeterminate state, ensuring a successful boot.

If the SPI-NOR flash isn't used as a boot device, this power control circuitry is not required.

10. SPI-NAND Flash

The SP7350 supports SPI-NAND flash for booting. To boot from an SPI-NAND flash, set the bootstrap pins IV_MX[6:2] to [1 1 1 0 1]. The SP7350 supports either 2k-sector with 1 or 2 planes or 4k-sector with 1 plane. When using a 1.8V flash chip, the maximum clock frequency is 153 MHz. It's advisable to use a 1.8V flash chip for optimal high-speed operation.

10.1 SPI-NAND Interface of SP7350

The SPI-NAND flash interface pins connect to GPIO30 ~ GPIO35, corresponding to D0, D2, CLK, D1, D3, and CSB signals.

The VDD_DVIO_2 power group, comprising GPIO20 and GPIO28 to GPIO37 pins, supports both 1.8V and 3.3V operations.

The SP7350 also supports a second pin-out for SPI-NAND flash, using the same interface pins as SPI-NOR flash. These connect to GPIO21 ~ GPIO26 for D2, CLK, D1, D3, CSB, and D0 signals. The existing circuitry for SPI-NOR flash can be used interchangeably with SPI-NAND flash.

The VDD_DVIO_1 power group, comprising GPIO21 to GPIO27 pins, supports both 1.8V and 3.3V operations.

10.2 SPI-NAND Flash Chip

For wiring the SPI-NAND flash, refer to the provided schematics. Connect the VDD power pins of the SPI-NAND flash to the SPINAND_SW power source derived from VDD_DVIO_2 power of GPIO30 to GPIO35. Ensure power pins connect to bypass capacitors for stable operation and improved signal integrity. For D2, D3, and CSB signals, include 10kΩ pull-up resistors by default.

If the SPI-NAND flash interface is unused, these pins can function as DVIO pins.

10.3 Power Control

Power to the SPI-NAND flash is controlled by the peripheral reset signal, PER_RESETB. When PER_RESETB is active (LOW), the SPI-NAND flash power is disabled and enabled when the signal is inactive. This power control mechanism assists in recovering the SPI-NAND flash from an undefined state, ensuring successful booting.

If the SPI-NAND flash is not used for booting, this power control circuitry is unnecessary.

11. 8-bit NAND Flash

The SP7350 supports booting from 8-bit NAND flash. To boot from an 8-bit NAND flash, set the bootstrap pins IV_MX[6:2] to [1 0 0 0 1]. The SP7350 is compatible with 2k-sector, 4k-sector, or 8k-sector NAND flash. For optimal high-speed performance, it's recommended to use a 1.8V VCCQ power supply.

11.1 8-bit NAND Interface of SP7350

The 8-bit NAND flash interface connects to GPIO20, GPIO21, GPIO23 to GPIO36, corresponding to RDY0, WP_B, RE_B, CLE, ALE, WE_B, D0 to D7, DQS, and D4 to D7 signals.

Note that the 8-bit NAND uses both the VDD_DVIO_1 power group (GPIO21 to GPIO27) and the VDD_DVIO_2 power group (GPIO20, GPIO28 to GPIO37). Both power groups should receive the same voltage, either 1.8V or 3.3V.

11.2 SPI-NAND Flash Chip

For wiring the 8-bit NAND flash, refer to the provided schematics. Connect the VCC_x (where x ranges from 1 to 8) power pins to 3.3V. Connect VCCQ_x (where x ranges from 1 to 8) to the FLASH_SW power source derived from VDD_DVIO_1 (GPIO21 to GPIO27). Ensure that both VCC_x and VCCQ_x power pins are connected to bypass capacitors for stable operation and improved signal integrity. The RE_B signal should have a default 10kΩ pull-up resistor.

If the 8-bit NAND flash interface is unused, these pins can serve as DVIO pins.

11.3 Power Control

The power for the 8-bit NAND flash shares circuitry with the SPI-NOR flash power control. It's governed by the peripheral reset signal, PER_RESETB. When PER_RESETB is active (LOW), the power to the 8-bit NAND flash is disabled, and it's enabled when the signal is inactive. This power control mechanism helps recover the 8-bit NAND flash from an indeterminate state, ensuring successful booting.

12. UART Console

By default, UART0 serves as the system's main console (CA55), while UART6 serves as the console for FreeRTOS (CM4).

12.1 Main Console

i-boot (ROM code), x-boot, BL31 (TF-A), OP-TEE, U-Boot, and Linux utilize UART0 as their console. Note that i-boot, being ROM code, is not modifiable by users. Users can only alter x-boot, BL31 (TF-A), OP-TEE, U-Boot, or Linux to use a different UART as the system's main console.

12.1.1 UA0 Pins of SP7350

UART0 is set to use GPIO50 (TXD) and GPIO51 (RXD) by default.

GPIO50 and GPIO51 are dual-voltage IO pins belonging to the VDD_DVIO_AO_1 power group.

12.1.2 Voltage Translator and UA0 Port

The voltage translator for UART0 consists of Si2302 (N-channel MOSFET) and resistors, which convert the signal levels of UART0 from VDD_DVIO_AO_1 (either 1.8V or 3.0V) to 3.3V and vice versa.

If VDD_DVIO_AO_1 uses 3.3V power, the voltage translator is unnecessary.

12.2 CM4 Console

FreeRTOS uses UART6 as its default console. Users have the flexibility to modify the FreeRTOS software to utilize a different UART as the console.

12.2.1 UA6 Pins of SP7350

UART6 is configured to use GPIO80 (TXD) and GPIO81 (RXD) by default.

GPIO80 and GPIO81 are 1.8V power GPIO pins belonging to the AO_1V8 power group.

12.2.2 Voltage Translator and UA6 Port

The voltage translator for UART6 consists of Si2302 (N-channel MOSFET) and resistors, converting the signal levels of UART6 from AO_1V8 (1.8V) to SYS_3V3 (3.3V) and vice versa.

13. USB2.0

USB 2.0 supports both High-speed, Full-speed and Low-speed transfers and is compatible with both host and device configurations. USB On-The-Go (OTG) extends the capabilities of USB 2.0 by enabling devices to dynamically switch between host and peripheral roles as needed. Please note that SP7350 supports SRP and HNP but not ADP.

13.1 USB2.0 Port of SP7350

Please refer to the provided schematics for detailed USB 2.0 port and power connections.

• USB20_DP and USB20_DM: These are the differential data signal pairs operating at 480 MHz. Maintain a differential impedance of 90Ω across the entire trace pair on the PCB.

• USB20_VBUS: Connect this pin to the VBUS of a mini-B, mini-AB, micro-B, or micro-AB socket to detect VBUS presence during device mode or OTG function use.

• USB20_AVDD33: Connect to a 3.3V power source and add bypass capacitors for stable operation and improved signal integrity.

• USB20_AVDD18: Connects to an internal 1.8V LDO. Leave unconnected.

• USB20_R_TEST: For internal testing only. Leave unconnected.

13.2 Type A Receptacle

Refer to the type A receptacle schematics below:

• Pin 1: VBUS power connected to 5V via current limit circuitry.

• Pins 2 and 3: Differential pair of data signals.

• Pin 4: Ground.

It's recommended to add ESD protection diodes for USB20_DP and USB20_DM signals.

13.3 VBUS of Type A Receptacle

Refer to current limit circuitry of VBUS of Type A receptacle. R230 sets the current limit of VBUS (U26). The current limit is calculated using the formula I_LIM = 6800/R230. In this example, R230 is 6.8 kΩ, the current is limited at 1.0A. That is,

I_LIM = 6800/6800 = 1.0 (A)

13.4 Micro-AB Receptacle

Refer to the micro-AB receptacle schematics below:

• Pin 1: VBUS power connected to 5V via current limit circuitry.

• Pins 2 and 3: Differential pair of data signals.

• Pin 4: ID signal to detect A device (ID = LOW) or B device (ID = HIGH).

• Pin 5: Ground.

It's recommended to add ESD protection diodes for USB20_DP and USB20_DM signals.

13.5 VBUS of Micro-AB Receptacle

Refer to the VBUS on/off control and current limit circuitry of micro-AB socket below. R230 sets the current limit of VBUS (U25). The current limit is calculated using the formula I_LIM = 6800/R217. In this example, R217 equals to 6.8 kΩ, the current is limited at 1.0A. That is,

I_LIM = 6800/6800 = 1.0 (A)

Note that R218 and C247 are requested and defined by OTG specification. Do not alter their values.

The UPHY0_DRV5V_EN signal controls VBUS on/off states, generated by the OTG hardware of SP7350.

13.6 OTG

For OTG support, ID of mini-AB or micro-AB socket should connect to GPIO19 with a 10 kΩ pull-up resistor (pull up to 1.8V since GPIO19 is a 1.8V GPIO). GPIO18, from OTG hardware, controls VBUS power. It's a low-active signal, so an inverter controls the current limit chip TMI6263BH.

If OTG is not supported, ID signal can directly control UPHY0_DRV5V_EN via an inverter.

GPIO18 and GPIO19 can function as GPIO pins.

14. USB3.0

The USB3 interface is compliant to USB 3.1 Gen 1 standard with data rate of 5Gbps and supporting Dual-Role Device (DRD). USB 3.0 Dual-Role Data (USB3 DRD) enables a USB device to act as both a host and a peripheral device. This capability is also known as USB On-The-Go (USB OTG) in the context of USB 2.0.

14.1 USB3.0 Port of SP7350

Please refer to the provided schematics for detailed USB 3.0 port and power connections.

• USB3_REFCLK_P and USB_REFCLK_N: These are the input pair of differential reference clock and are intended for internal testing only. Please connect them to ground.

• USB3_DP and USB3_DM: These are the differential data signal pair operating at 480 MHz. When designing the PCB, please maintain a consistent differential impedance of 90Ω across the entire trace pair.

• USB3_TX0P and USB3_TX0M: These pins represent the differential TX signal pair for port 0 operating at 5 GHz. When designing the PCB, ensure a consistent differential impedance of 90Ω across the entire trace pair.

• USB3_RX0P and USB3_RX0M: These pins represent the differential RX signal pair for port 0 operating at 5 GHz. When designing the PCB, ensure a consistent differential impedance of 90Ω across the entire trace pair.

• USB3_TX1P and USB3_TX1M: These pins represent the differential TX signal pair for port 1 operating at 5 GHz. When designing the PCB, ensure a consistent differential impedance of 90Ω across the entire trace pair.

• USB3_RX1P and USB3_RX1M: These pins represent the differential RX signal pair for port 1 operating at 5 GHz. When designing the PCB, ensure a consistent differential impedance of 90Ω across the entire trace pair.

• USB3_ID: This ID pin should be left unconnected.

• USB3_RESREF: This pin is designated for the reference resistor. Connect it to a 200Ω, 1% precision resistor.

• USB3_VBUS: This pin detects the presence of VBUS power during device mode or DRD function use. Due to its input range of 0 to 3.3V, it should not be directly connected to VBUS. Instead, use a voltage divider circuitry.

• USB3_AVDD08: This pin is designated for 0.8V analog power. Connect to a 0.8V power source and include bypass capacitors for stable operation and improved signal integrity.

• USB3_DVDD08: This pin is designated for 0.8V digital power. Connect to a 0.8V power source and add bypass capacitors for stable operation and improved signal integrity.

• USB3_VDD33: This pin is designated for 3.3V power. Connect to a 3.3V power source and add bypass capacitors for stable operation and improved signal integrity.

14.2 Type-C Receptacle

The USB Type-C connector has seen widespread adoption due to its versatility, compact size, and unique reversible design. This allows for plugging in a Type-C cable in either orientation.

Refer to the Type-C receptacle schematics below. The Type-C connector accommodates two orientations of signal, making it usable regardless of orientation.

• USB30_TX0P/M and USB30_RX0P/M (port 0): Connect to A2/A3 and B11/B10 pins.

• USB30_TX1P/M and USB30_RX1P/M (port 1): Connect to B2/B3 and A11/A10 pins.

• USB3_DP/M: Directly connect to both A6/A7 and B6/B7 pins.

• VBUS: Connect A4/A9/B5/B9 pins to VBUS.

• CC1 and CC2: Connect these pins to the configuration channel (CC) detection chip.

For added protection, it's recommended to include ESD protection diodes for the following signals: USB30_DP/M, USB30_TX0_DP/M, USB30_RX0_DP/M, USB30_TX1_DP/M, and USB30_RX1_DP/M.

14.3 VBUS of Type-C Receptacle

Refer to the VBUS on/off control and current limit circuitry of the Type-C socket below. The USB30_VBUS_EN signal controls the on/off state of VBUS. Resistor R214 sets the current limit for VBUS (U24). The current limit is determined by the formula I_LIM = 6800/R214. With R214 set at 6.8 kΩ, the current limit is I_LIM = 1.0A.

14.4 CC Detection Circuitry for Type-C Receptacle

Refer to the schematics below for the Configuration Channel (CC) detection circuitry designed specifically for the Type-C receptacle of USB 3.0. Here are the descriptions of the key pins for the TUSB321 device:

• CC1 and CC2 Pins: These pins are directly connected to the CC1 and CC2 pins of the Type-C receptacle. The TUSB321 device uses them to determine port attachment, detachment, cable orientation, and role detection.

• ID Pin: An open-drain output that goes LOW when the CC pins detect device attachment in DFP mode or when acting as a dual-role (DRP) source.

• DIR Pin: An open-drain output indicating the detected plug orientation:

  • L: Type-C plug position 1

  • H: Type-C plug position 2

• PORT Pin:

  • H: DFP (Pull-up to VDD for DFP mode)

  • NC: DRP (Leave unconnected for DRP mode)

  • L: UFP (Pull-down or tie to GND for UFP mode)

• CURRENT_MODE Pin:

  • L: Default Current (Pull-down to GND or leave unconnected)

  • M: Medium (1.5A) current (Pull-up to VDD with 500 kΩ resistor)

  • H: High (3.0A) current (Pull-up to VDD with 10 kΩ resistor)

• VBUS_DET Pin: This pin detects VBUS with an input range of 5V to 28V. VBUS detection determines UFP attachment. A 900 kΩ serial resistor is required between VBUS and the VBUS_DET pin.

The PORT pin is left unconnected, indicating DRP (Dual Role Port) mode is selected. The CURRENT_MODE pin is also left unconnected, signifying that the default current mode is selected. The USB30_VBUS_EN signal, an inversion of USB30_CC_ID, controls the on/off state of VBUS.

14.5 Type-A Receptacle

If a Type-A receptacle of USB 3.0 is used, connect USB30_TX0P/M, USB30_RX0P/M (port 0), and USB3_DP/M to the Type-A connector. It's recommended to include ESD protection diodes for the following signals: USB30_DP/M, USB30_TX0_DP/M, and USB30_RX0_DP/M. Ensure that VBUS is provided with a current limit.

15. MIPI-RX4

The MIPI-RX4 (CSI) channel supports two data and one clock lanes (2d1c) and 2 virtual channels. Each data lane can handle transmission speeds up to 1.5 Gbps.

15.1 MIPI-RX4 Port of SP7350

Refer to the schematic below for details. MIPI4_DP[1:0] and MIPI4_DN[1:0] are differential data pairs, while MIPI4_SP and MIPI4_SN are differential clock pairs for MIPI-RX4. MIPI4_AVDD08 and MIPI4_AVDD18 power pins supply analog 0.8V and 1.8V to the MIPI-RX4 PHY, respectively. It's crucial to add bypass capacitors to filter out high-frequency noise and use ferrite beads on both power and ground lines for stable operation.

15.2 15-Pin Camera Connector (2d2c) of Raspberry Pi

The schematic shows CON4, a 15-pin camera FFC connector (1.0mm pitch) compatible with Raspberry Pi. Apart from connecting MIPI-RX4 differential-pair signals, it also connects to I2C channel 2 (I2C2) for camera setup and control. The I2C signal level defined by the Raspberry Pi camera is 3.3V. Voltage translators are used to convert the I2C signal level from VDD_DVIO_AO_3, which can be either 3.3V or 1.8V, to 3.3V. If VDD_DVIO_AO_3 is powered by 3.3V, the voltage translator is not required. CAM_IO_0_4 and CAM_IO_1_4 are IO signals defined by the camera. Some cameras require setting these signals to HIGH for normal operation.

It's recommended to include ESD protection diodes for MIPI-RX4 data and clock differential pairs.

16. MIPI-RX5

The MIPI-RX5 (CSI) channel has four data and one clock lanes (4d1c) and supports 4 virtual channels. Each data lane can transmit up to 1.5 Gbps.

16.1 MIPI-RX5 Port of SP7350

Refer to the schematic for details. MIPI5_DP[3:0] and MIPI5_DN[3:0] are differential data pairs, while MIPI5_SP and MIPI5_SN are differential clock pairs. MIPI5_AVDD08 and MIPI5_AVDD18 power pins provide analog 0.8V and 1.8V to the MIPI-RX5 PHY, respectively. Bypass capacitors and ferrite beads on power and ground lines are recommended for stable operation.

16.2 22-Pin Camera Connector (4d1c) of Raspberry Pi

The schematic shows CN22, a 22-pin camera FFC connector (0.5mm pitch) compatible with Raspberry Pi. Besides MIPI-RX5 differential-pair signals, it connects to I2C channel 3 (I2C3) for camera setup and control. Because the signal level of I2C defined by Raspberry Pi camera is 3.3V, voltage translators are needed to adjust the I2C signal level from SYS_1V8 (1.8V) to 3.3V. Pins 17 and 18 are camera-defined IO signals. Some cameras require setting these to HIGH for operation.

It's recommended to include ESD protection diodes for MIPI-RX5 data and clock differential pairs.

17. CPIO and MIPI-RX2/RX3

CPIO is Sunplus proprietary IP for chip-to-chip or die-to-die communication, supporting 4 data lanes for both TX and RX. The maximum bandwidth is 1.0 GiB/s for chip-to-chip communication and 4.8GiB/s for die-to-die communication. MIPI-RX2 and RX3 channels share pins with CPIO. When CPIO is disabled, MIPI-RX2 and MIPI-RX3 channels can be used.

17.1 CPIO Port of SP7350

Refer to the schematic for details. CPIOR-eCHRDY_I and CPIOR-eCHRDY_O are channel-ready signals with "I" indicating input and "O" indicating output. They should be connected reciprocally. CPIOR-eRESET is the reset signal. TX and RX pairs can connect using SWAP or CROSSOVER modes.

The power pins CPIOR_AVDD08 and CPIOR_AVDD18 supply 0.8V and 1.8V analog voltages to the CPIO PHY, respectively. To effectively filter out high-frequency noise from the power supply lines, it's essential to include bypass capacitors. Furthermore, using ferrite beads on both the power and ground lines is recommended to maintain stable operation.

17.1.1 Swap Mode Connection

Refer to figure below for Swap mode connection.

In Swap mode, lane 0 swaps with lane 3, and lane 1 swaps with lane 2 for both TXD and RXD pairs on the slave side. Refer to table below:

17.1.2 Crossover Mode Connection

Refer to figure below for Crossover mode connection.

In Crossover mode, TXD pairs swap with RXD pairs, TXC pairs swap with RXC pairs, and the RDY_O and RDY_I signals are reciprocal on the slave side. Refer to table below:

Note that RDY_I and RDY_O are signal-end signals.

17.2 MIPI-RX2 and MIPI-RX3

Note that MIPI-RX2 is not available for version A chips.

When CPIO is disabled, MIPI-RX2 and MIPI-RX3 are available for use. MIPI-RX2 supports four data and one clock lanes (4d1c) with 4 virtual channels if MIPI-RX3 is not enabled. However, if MIPI-RX3 is enabled, both MIPI-RX2 and RX3 support two data and one clock lanes (2d1c). Each data lane can transmit up to 1.5 Gbps. Please refer to the table for pin sharing between MIPI-RX2, MIPI-RX3, and CPIO.

18. MIPI-TX

MIPI TX output port that can be configured as CSI for camera output or DSI for display output. This interface provides four data and one clock lanes with data rate of 1.5Gbps per lane.

18.1 MIPI-TX Port of SP7350

Refer to the schematic for details. MIPITX_OUTP[3:0] and MIPITX_OUTN[3:0] are differential data pairs, while MIPITX_CLKP and MIPITX_CLKN are differential clock pairs. MIPITX_AVDD18 power pin provide analog 1.8V to the MIPITX PHY. Bypass capacitors and ferrite beads on power and ground lines are recommended for stable operation.

18.2 15-Pin Display Connector (2d2c) of Raspberry Pi

The schematic shows CON6, a 15-pin display FFC connector (1.0mm pitch) compatible with Raspberry Pi. Apart from connecting MIPITX differential-pair signals, it also connects to I2C channel 6 (I2C6) for display setup and control. The I2C signal level defined by the Raspberry Pi camera is 3.3V. Voltage translators are used to convert the I2C signal level from SYS_1V8 (1.8V) to 3.3V.

It's recommended to include ESD protection diodes for MIPITX data and clock differential pairs.

19. Audio I2S Interface

The audio interface of SP7350 comprises one bidirectional and two unidirectional I2S interfaces. Each interface supports 2-channel (L/R) operation and can function in either master or slave mode, with configurable clock frequency and LRCK polarity.

For a detailed pin-out of the SP7350 audio I2S interface, refer to the https://sunplus.atlassian.net/wiki/spaces/C3/pages/1971126471/SP7350+Specification#10.-Audio-Interface.

19.1 Audio I2S ADC and DAC Chip

Below is the pin-out for channel 0 of the SP7350 audio I2S interface:

In the schematics, an ES8316 audio ADC and DAC chip is utilized. The I2S interface signals of the ES8316 connect to position X1 of channel 0 on the SP7350. The MCLK pin of the ES8316 connects to the EXT_DAC_XCK (GPIO83) audio clock output pin of the SP7350. Additionally, the I2C interface of the ES8316 connects to I2C4 on the SP7350, with I2C4_CLK and I2C4_DATA configured to GPIO90 and GPIO91, respectively.

Bypass capacitors are added to all power pins for improved power integrity, and ferrite beads are used on power lines to filter high-frequency noise and interference.

19.2 4-Pole Audio Jack

A 4-pole 3.5mm TRRS plug is used for the headset, as depicted in the figure below.

The CTIA TRRS standard, commonly used by modern smartphones and Apple devices, defines the pin-out as:

• Tip: Left Audio

• Ring 1: Right Audio

• Ring 2: Ground

• Sleeve: Microphone

In the schematics, the MIC_LIN2 signal from the LIN2 pin of the ES8316 connects to pin 1 of the PJ-393-8PJ audio jack, with a bias circuit driven by the MICBIAS pin of the ES8316. HPR_OUT (from LOUT pin) and HPL_OUT (from ROUT pin) connect to pins 5 and 7 of the audio jack, respectively.

According to the specifications of the PJ-393-8PJ audio jack, when the audio plug is not inserted, pins 1 and 2, pins 3 and 4, pins 5 and 6, and pins 7 and 8 remain connected. Based on the schematics, if the audio plug is not inserted:

• MIC_LIN2 is connected to GND

• HPR_OUT is connected to SPKR_OUT

• HPL_OUT is connected to SPKL_OUT

The HPR_OUT and HPL_OUT signals are routed to the audio amplifier. When the audio plug is inserted, MIC_LIN2, HPR_OUT, and HPL_OUT exclusively come from the headset.

It's recommended to include ESD protection diodes for MIC_RIN2, SPK1_N, and SPK1_P signals if the devices are human-accessible.

19.3 Audio Amplifier, Speaker and Microphone

In the schematics, an HT6872 audio amplifier drives a small speaker. The SPK_IN signal is mixed from the SPKR_OUT and SPKL_OUT signals. The SPK_CTL signal should connect to a GPIO pin, set to HIGH to enable the amplifier. The microphone output (MIC_RIN2 signal) connects to the RIN2 pin of the ES8316, with a bias circuit driven by the MICBIAS pin of the ES8316.

It's recommended to include ESD protection diodes for MIC_RIN2, SPK1_N, and SPK1_P signals if the devices are human-accessible.

20. CA55 JTAG Interface

The SP7350 board supports the JTAG ICE interface for Cortex A55 (CA55). This interface enables developers to perform real-time debugging by connecting to the CA55 processor's JTAG (Joint Test Action Group) interface.

20.1 CA55 JTAG Pins

The interface pins are mapped to GPIO13 to GPIO17, corresponding to the TRST_N, TMS, TCK, TDI, and TDO signals of JTAG.

To activate the JTAG interface, users should configure G1.1[8] to 1 or set bootstrap pin IV_MX[1] to 0. Please note that the JTAG interface pins share functionality with RGMII pins and cannot be used simultaneously.

20.2 CA55 JTAG Pin-header

Referring to the schematics below, the standard JTAG connector is a 2x10-pin 100mil-pitch pin-header. Pin 1 serves as the reference voltage for JTAG signals, while Pin 2 provides optional VCC power. The JTAG_nSRST signal (low-active), derived from the RESETB signal, functions as the system reset. It's important to note that the CA55 JTAG signals operate at 1.8V.

21. CM4 JTAG/SWD Interface

The SP7350 also supports the JTAG and SWD ICE interfaces for Cortex M4 (CM4). Both interfaces allow developers to debug their target systems in real-time. JTAG is the traditional interface, while SWD (Serial Wire Debug) is a two-wire protocol designed specifically for ARM processors, offering an alternative when pin resources are limited or PCB layout is constrained.

21.1 CM4 JTAG/SWD Pins

For JTAG, the interface pins are GPIO88 to GPIO93, corresponding to TRST_N, TMS, TCK, TDI, and TDO signals. For SWD, the pins are GPIO89, GPIO90, and GPIO93, corresponding to SWDIO, SWCLK, and SWDO signals.

To activate the JTAG interface, users should configure G1.5[0] to 1.

21.2 CM4 JTAG and SWD Pin-header

Referring to the schematics below, the standard JTAG/SWD connector is a 2x10-pin 100mil-pitch pin-header. Pin 1 provides the reference voltage for JTAG signals, and Pin 2 offers optional VCC power. Similar to CA55, the CM4_JTAG_nSRST signal (low-active) for system reset is derived from the RESETB signal. Note that the CM4 JTAG signals operate at 1.8V.

22. UA2AXI Interface

The UA2AXI interface is a proprietary UART interface by Sunplus that connects to the internal AXI bus of the SP7350. The UA2AXI interface shares its interface with UADBG (UART5), which is a standard UART and can be probed by Linux.

22.1 UA2AXI Pins of SP7350

The interface pins for UA2AXI are GPIO13 (TXD) and GPIO14 (RXD). Both GPIO13 and GPIO14 are 1.8V power GPIO pins belonging to the SYS_1V8 power group.

22.2 Voltage Translator and UA2AXI Port

The voltage translator for UA2AXI comprises the Si2302 (N-channel MOSFET) and resistors, which convert the signal levels of UA2AXI from SYS_1V8 (1.8V) to SYS_3V3 (3.3V) and vice versa.