Support for FT232R in sync bitbang mode implemented

Development Boards MicroMod
1

Hi all,

I added a support for USB-JTAG adapters, based on FT232R chip. Synchronous bit bang mode is used. Schematics and patch are available here: http://vak.ru/doku.php/proj/bitbang/bitbang-jtag

Best wishes,

Serge

2

Well done Serge.

OK, stupid question time. I already spent the $$ on an Olimex ARM-USB-OCD. My impression is that an interface using the Sparkfun breakout would have about the same performance, but at a lower cost.

Is that basically correct?

3

Olimex ARM-USB-OCD is based on FT2232 chip, which should be somewhat faster than FT232R. It has more intelligent MPSSE protocol engine. Probably twice faster. It would be interesting to compare these chips, using OpenOCD flash programming commands as a benchmark.

Serge

4

hsutherl:
I already spent the $$ on an Olimex ARM-USB-OCD. My impression is that an interface using the Sparkfun breakout would have about the same performance, but at a lower cost. Is that basically correct?

I tested the speed of FT232R adapter compared with Olimex ARM-USB-Tiny. Olimex (based on FT2232D) is much faster: about 90 times. So your money surely are not lost. :)

I think, the best board for homebrew JTAG adapters is not FT232R Breakout, but [DLP-USB1232H ($29 on Digi-Key).](DLP Design USB Product Page)

5

Interesting (and a little surprising). I also have a Sparkfun FT232 breakout but have only used it in serial comm mode, not bitbang. I was thinking of trying the same test, but you got there ahead of me.