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Serial Device
Kernel Setup
Enter the kernel configuration by running the following command in the top directory of project.
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Execute the make command to build the Linux image.
ConfigFS
Configure serial gadget through configfs saved as a file named setup_serial.
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#!/bin/sh KERNEL_PATH=/lib/modules/`uname -r`/kernel GADGET_PATH=$KERNEL_PATH/drivers/usb/gadget FUNCTION_PATH=$GADGET_PATH/function COMPOSITE=$GADGET_PATH/libcomposite.ko U_SERIAL=$FUNCTION_PATH/u_serial.ko insmod $COMPOSITE insmod $U_SERIAL # disable debug message echo 0 > /sys/module/sunplus_udc/parameters/dmsg mkdir -p /sys/kernel/config mount -t configfs none /sys/kernel/config # USB2.0 configurations cd /sys/kernel/config/usb_gadget # create gadget folder mkdir g1 cd g1 # setup gadget 1 echo 64 > bMaxPacketSize0 echo 0x200 > bcdUSB # composite class echo 0x02 > bDeviceClass mkdir -p configs/c.1 mkdir -p configs/c.1/strings/0x409 echo "USB2.0 Serial Console" > configs/c.1/strings/0x409/configuration mkdir strings/0x409 echo "1234" > strings/0x409/serialnumber echo "Sunplus" > strings/0x409/manufacturer echo "SP7350" > strings/0x409/product mkdir functions/acm.gs0 ln -s functions/acm.gs0 configs/c.1 # bind UDC echo "f8102800.usb" > UDC # USB3.0 configurations cd /sys/kernel/config/usb_gadget # create gadget folder mkdir g2 cd g2 # setup gadget 2 echo 64 > bMaxPacketSize0 echo 0x300 > bcdUSB # composite class echo 0x02 > bDeviceClass mkdir -p configs/c.1 mkdir -p configs/c.1/strings/0x409 echo "USB3.0 Serial Console" > configs/c.1/strings/0x409/configuration mkdir strings/0x409 echo "5678" > strings/0x409/serialnumber echo "Sunplus" > strings/0x409/manufacturer echo "SP7350" > strings/0x409/product mkdir functions/acm.gs1 ln -s functions/acm.gs1 configs/c.1 # bind UDC echo "f80a1000.dwc3" > UDC |
Test Configuartions
Use sh setup_serial command to configure USB 2.0 and USB3.0 device controllers as serial gadgets.
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In Device Manager of Windows PC, “USB Serial Device (COM17)“ (USB2.0 serial gadget) and “USB Serial Device (COM18)“ (USB3.0 serial gadget) will show up in “Ports (COM & LPT)”.
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Serial Device Test
Use the communication tool of Putty for the test with a Windows PC.
TX Test for USB2.0 Serial Gadget
Use the following command to transfer characters of “SP7350 USB2.0 Serial Gadget TX Test“ to COM17 through ttyGS0 (USB2.0 serial gadget).
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The characters will be received by COM17 open in Putty.
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TX Test for USB3.0 Serial Gadget
Use the following command to transfer characters of “SP7350 USB3.0 Serial Gadget TX Test“ to COM18 through ttyGS1 (USB3.0 serial gadget).
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The characters will be received by COM18 open in Putty.
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RX Test for USB2.0 Serial Gadget
Use the following command to receive characters transferred from COM17 through ttyGS0 (USB2.0 serial gadget).
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Input the characters of “SP7350 USB2.0 Serial Gadget RX Test" in Putty with COM17 and press “Enter”. The characters will be received by COM4 (console) open in Putty.
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RX Test for USB3.0 Serial Gadget
Use the following command to receive characters transferred from COM18 through ttyGS1 (USB3.0 serial gadget).
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Input the characters of “SP7350 USB3.0 Serial Gadget RX Test" in Putty with COM18 and press “Enter”. The characters will be received by COM4 (console) open in Putty.
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Serial Gadget Console
For console support, it is more convenient to use precomposed configurations (build-in) instead of configfs. Take USB2.0 Serial Gadget for example.
Kernel Setup
Enter the kernel configuration by running the following command in the top directory of project.
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# make kconfig |
Select submenus for USB 2.0 controller : Device Drivers > USB support > USB support > USB Gadget Support > USB Peripheral Controller. Select <*> for “Sunplus USB 2.0 Device Controller“.
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Select submenus for precomposed configurations : Device Drivers > USB support > USB support > USB Gadget Support > USB Gadget precomposed configurations. Select <*> for “Serial Gadget (with CDC ACM and CDC OBEX support)”.
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Select submenus for precomposed configurations : Device Drivers > USB support > USB support > USB Gadget Support. Select [*] for “Serial gadget console support“.
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Test Configurations
Add an entry in linux/rootfs/initramfs/disk/etc/inittab to set the terminal to connect to ttyGS0.
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Add “ttyGS0” in linux/rootfs/initramfs/disk/etc/securetty
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Execute the make command to build the Linux image.
Serial Gadget Console Test
After updating the image to a SP7350 platform and booting the system, kernel messages during boot are shown in COM4 of Putty which is the default console set in uboot.
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After connecting the SP7350 platform to the Windows PC with an USB OTG cable, “login[144]: root login on 'ttyGS0'“ will show up in COM4 of Putty. There is an USB serial device (COM8) appearing in Device Manager.
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Open Putty with COM8 and it can receive text input from the user.
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