Electronics > Electronics

ft232r problems.

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hey guys,
has any one got any experience with the ft232r USB to UART chip?
from the datasheet it looks fairly straight forward.
reading about it on the internet i haven't found anyone else with the similar problems to me. indeed, it seems from all reports a fairly straight forward component.

so, here's the background,
i have made and etched the attached circuit:

i am reasonably sure there are no bad connections or shorts.
when i plug it in on a linux computer it does not appear under /proc/bus/usb/devices.
when it is first plugged in (or when the uhci_hcd driver is removed and reloaded) i get the following output to the sys log at the same time as the RX and TX LEDs flash:

--- Code: ---[17180187.476000] usb 3-2: new full speed USB device using uhci_hcd and address 2
[17180187.596000] usb 3-2: device descriptor read/64, error -71
[17180187.820000] usb 3-2: device descriptor read/64, error -71
[17180188.036000] usb 3-2: new full speed USB device using uhci_hcd and address 3
[17180188.156000] usb 3-2: device descriptor read/64, error -71
[17180188.380000] usb 3-2: device descriptor read/64, error -71
[17180188.596000] usb 3-2: new full speed USB device using uhci_hcd and address 4
[17180189.004000] usb 3-2: device not accepting address 4, error -71

--- End code ---

so, my hypothysis is that the ft232r must be functional to some extent as the LEDs flash when the relevant driver is reloaded.
i suspect that there some sort of interference going on that is preventing communication between the ft232r and the host computer.

i will try a different USB cable if i can pick one up at work and if that doesn't work, etch another board and rebuild but i'm reasonably confident the circuit is good.

has anyone used this chip before and was it as temperamental as i'm finding it?
could someone compair my schematic to the datasheet and see if i'm missing anything obvious please? (it wouldn't be the first time a dumb typo on my part has had me scratching my head for days...)




I use that chip on my BrainBot robot, interfacing to a gumstix verdex. The driver was included, but disabled, so we had to enable it (which on the gumstix required a re-build).

Once I had that done, when I plugged it in I get a bit of text on the console (don't remember off the top of my head what), which was more than what I got when the driver wasn't enabled.

Okay, I just booted up my gumstix, and this is what I get when I plug in the FT232 (once it has fully booted up):

# usb 1-2: new full speed USB device using pxa27x-ohci and address 6
usb 1-2: configuration #1 chosen from 1 choice
usbcore: registered new driver usbserial
drivers/usb/serial/usb-serial.c: USB Serial Driver core
drivers/usb/serial/usb-serial.c: USB Serial support registered for FTDI USB Serial Device
ftdi_sio 1-2:1.0: FTDI USB Serial Device converter detected
drivers/usb/serial/ftdi_sio.c: Detected FT232BM
usb 1-2: FTDI USB Serial Device converter now attached to ttyUSB0
usbcore: registered new driver ftdi_sio
drivers/usb/serial/ftdi_sio.c: v1.4.3:USB FTDI Serial Converters Driver

- Jon

hi Jon,
yea, it's not a driver issue as i should be able to see the vendor id and the device id under the /proc/bus/usb/devices file for any USB device even with no driver loaded.
as a result i'm reasonably sure it's a hardware problem.


One issue I had when I was building my first FT232 board was in the datasheet there are two different layouts for the chips, with completely different pin numbers depending on whether you're looking at the MLF package or the TSSOP package...

- Jon

yea, i'm using ft232rl which uses the SSOP package format, but i am wondering if i'm doing something dumb like that.



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