USB to serial adapter
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Informations on this page are not guaranteed !!
This type of adapter allows you to add several serial (RS232) ports to your APF board, through the USB Host interface (only available on DevFull & APF27)
Tested materials
 |
Warning: Due to some bugs in the (uggly) ISP1761 driver, USB to serial adapters are currently not usable on the APF9328 ! |
The commercial adapters can be separated in 2 categories, because there are only 2 USB<->serial low cost chipmakers:
- FTDI one
- Prolific one (pl23xx)
| Adapter Model | Chip | Status APF9328 / APF27 |
Driver | Comments | |
|---|---|---|---|---|---|
| Trendnet TU-S9 | pl2303 | pl2303 | |||
| XXXX | |||||
Installation
$ make linux26-menuconfig
Device Drivers --->
[*] USB support --->
...
*** USB port drivers ***
<M> USB Serial Converter support
...
<M> USB FTDI Single Port Serial Driver
<M> USB Prolific 2303 Single Port Serial Driver
$ make linux26 && make
copy following drivers on your target or reflash your rootfs (for more infos, see this page)
drivers/usb/serial/ftdi_sio.ko drivers/usb/serial/pl2303.ko drivers/usb/serial/usbserial.ko
Usage
- be sure that your USB Host is running on your board: explanations are here
- plug your USB adapter (here a Prolific one)
usb 1-1: full speed USB device using mxc-ehci and address 2 usb 1-1: configuration #1 chosen from 1 choice usb 1-1: New USB device found, idVendor=067b, idProduct=2303 usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0 usb 1-1: Product: USB-Serial Controller D usb 1-1: Manufacturer: Prolific Technology Inc.
- Load the module, for example if you have a Prolific based adapter:
# modprobe pl2303 usbcore: registered new interface driver usbserial usbserial: USB Serial Driver core usbserial: USB Serial support registered for pl2303 pl2303 1-1.1:1.0: pl2303 converter detected usb 1-1.1: pl2303 converter now attached to ttyUSB0 usbcore: registered new interface driver pl2303 pl2303: Prolific PL2303 USB to serial adaptor driver #
- a new serial device will then appear under /dev/ttyUSBN (N starting at 0 and depending on the number of adapters detected).
 |
Note: You can use now this new device like a standard Linux serial port |
Troubelshooting
- If your USB <-> Serial converter doesn't seem to work, run the dmesg command. You should read this thread if you see some disconnection data like this :
[ 2445.568000] usb 1-1.4: new full speed USB device using uhci_hcd and address 22 ... [ 2446.964000] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0 [ 2446.964000] ftdi_sio 1-1.4:1.0: device disconnected
Check that you have read/write rights on /dev/ttyS0 (ie your serial port): your user ID (here julien) should be part of the serial port access group (here dialout):
$ ls -al /dev/ttyS0 crw-rw---- 1 root dialout 4, 64 2009-05-15 14:56 /dev/ttyS0 $ id uid=1000(julien) gid=1000(julien) groupes=4(adm),20(dialout),...
