FTDI TTL-232R-3V3 and RBBB on mac?

Problems uploading, serial connections, BUBs, P4, FTDI cables, etc
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se4587
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Joined: Tue Mar 02, 2010 10:02 pm

FTDI TTL-232R-3V3 and RBBB on mac?

Post by se4587 » Tue Mar 02, 2010 10:08 pm

Hi everyone, I'm hoping I'm just having an operator error, but I can't get my RBBB to communicate with my iMac using this FTDI cable. I always get an "avrdude: stk500_recv(): programmer is not responding" error twice. I've tried both the ports ("/dev/tty.usbserial-FTCX72C8" and "/dev/cu.usbserial-FTCX72C8") and almost every board option. Pin 13 is blinking every second while powered, and I can get a flicker on the RX line when it tries to upload, but that's it.

Any ideas?

Thanks!

paul
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Joined: Mon May 12, 2008 4:19 pm

Re: FTDI TTL-232R-3V3 and RBBB on mac?

Post by paul » Mon Mar 08, 2010 12:48 pm

Sorry for the slow reply - se4587,

Apparently missed your post when two people posted at about the same time.

If you have the RBBB powered by external power, disconnect from external power and see if you can get it to upload just from the cable.
Check the wires on the cable - GND is black - check the connectors - they tend to loosen up after a bit - push them toward connector with a jewelers screwdriver.

Incidentally, if you get it to program with the cable - you can remove cable and run on external power again.
The RBBB has 5V regulator and output is connected to the power pin on the cable, which I think might be at 3.3V so 3.3V <-> 5V (this is bad).
You can easily confirm voltage on cable with a meter.

There may be some chance that you damaged the chip in the cable but I would doubt it.

Hope that helps,

Paul

se4587
Posts: 2
Joined: Tue Mar 02, 2010 10:02 pm

Re: FTDI TTL-232R-3V3 and RBBB on mac?

Post by se4587 » Mon Mar 08, 2010 6:43 pm

I don't have the RBBB powered by anything else except the TTL-232R cable. I did check the connections, and even tried some different combinations (swap brown & green) but no dice. I guess my next option is to try it in a windows environment...

I did try one more thing today; I tried to convert this TTL-232R-3V3 into a TTL-232R-5V by shorting pin 1 (VCCIO) to the red wire (VCC). Per the datasheet, this should make the data 5v instead of 3.3v...but the VCCIO line is tied to the VCC33 (3.3v) output on pin 16, probably by a via or through a layer. I couldn't cut that line, so I just shorted pin 1 to 5v. Now the TTL-232R will power up my board as usual, but isn't even recognized as a port anymore on the computer :( So I think I fried the FT232RQ chip...or at least rendered it useless as a converter until I remove that short...hopefully it would still work after that...

Thanks for the reply though, Paul.
Seth

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