On Tue, Jan 4, 2011 at 1:31 AM, Xiaofan Chen wrote: > On Tue, Jan 4, 2011 at 3:20 PM, Xiaofan Chen wrote: >> On Tue, Jan 4, 2011 at 1:56 PM, Mark Rages wrote: >>> On Mon, Jan 3, 2011 at 11:51 PM, Xiaofan Chen wrot= e: >>>> However, I do not know of any support for PICs using FTDI >>>> based JTAG programmer other than the limit support of >>>> OpenOCD PIC32 support. >>>> >>>> On the other hand, if you want to buy a ready-made >>>> FT2232x based debugger, the price is not really that >>>> cheap compared to the US$35 PICKit 2. >>>> >>> >>> The FTDI cable I mentioned is $18. >>> >> >> One huge difference is that the FT2232x based ones can >> have two channel and the MPSSE mode is much better >> to deal with than the bit bang mode of FT232x. There are >> indeed serial based JTAG debuggers using FT232x but it >> is much slower and not popular at all. >> >> There were discussions in the OpenOCD about this >> and the consensus is that it is mostly not worth >> the efforts to use FT232x instead of FT2232x. >> > > http://forum.sparkfun.com/viewtopic.php?f=3D18&t=3D21411 > The author of the bitbabg-jtag says that FT2232D based > Olimex ARM-USB-Tiny is 90 times faster than his > FT232R based serial JTAG debugger. > I've got the FT232 cable on my desk and am testing it now. I made a Python script to set bitbang mode with libftdi and write a repeating 0x00,0xff pattern to it. If I set the baudrate to 1382400 I get 677 kbyte / s transfer to the chip. A scope confirms the data coming out as 1.38/2 MHz squarewave, with occasional gaps in it. So the 2232D chip can do 90 times faster than that? That would be 60 MB/sec, which is the theoretical maximum for USB 2.0 Hi-Speed mode. I must admit I'm a bit skeptical, but I don't have a 2232D on hand to experiment with. Regards, Mark markrages@gmail --=20 Mark Rages, Engineer Midwest Telecine LLC markrages@midwesttelecine.com --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .