[avrdude-dev] [bug #30559] Ft232 bit-bang support

[Roger Wolff]

Follow-up Comment #3, bug #30559 (project avrdude):

Dear avrdude maintainers, 

I'm going to attach a patch that uses the FT2xxR synchronous bitbang modes to
program the AVR chips. This can be done QUITE fast. I got over 2k/sec
programming+verifying yesterday. I don't understand what's changed since
yesterday, but I only  get just below 2k/sec today. :-( (this means over
4k/sec programming only). 

I THINK this throughput can be increased even further but I haven't been able
to get this to work just yet.

Previous versions of this "patch" relied on the non-free ftd2xx library from
FTDI. This one works with libftdi. 

I am not able to test it under windows. 

The reads from the device have to be asynchronous under Linux. I therefore had
to add a dependency on pthreads. 

Otherwise, it seems a deadlock would develop: while sending a datablock to the
FTDI, it needs to return the synchronous "return data". When the application
hasn't issued the read yet, the kernel will prevent the device from sending
the data, and then when the buffers in the ft2xxr fill up, it will also stop
accepting data, blocking the write.... 

I have found that there is also a new avrftdi programmer in the current
release. This programmer works for ft2232(h) chips and refuses to work for the
ft232r that I have here. 

(some) Arduino users will be able to download their sketches 4-10 times faster
with this patch. :-)


(file #24806)
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Additional Item Attachment:

File name: bw_ft245r.patch                Size:55 KB


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