Hi Robert, On Sat, May 03, 2014 at 07:21:36PM +0200, Robert Jarzmik wrote: > That maybe would deserve to be included > somewhere as a documentation reference for true Altera USB Blaster.
while at it, one should also mention somewhere that pin 6 and 8 are push-pull. > > We might as well send alternating 0x2e/0x2f to reset the state machine > > as soon as we are back into bit banging mode. If we knew how to access > > TRST at that point, we could avoid filling DR/IR with junk. > We might send something else that 0x00. Rather than 0x2e/0x2f, I would send > something like (computed PIN6 | computed PIN8 | TMS=1 | TCK=x), alternating x > between 0 and 1. Don't forget LED=1 to enable the output drivers. > > Maybe we can defer initialization? > I don't understand that part, would you enlighten me ? I was under the impression that ublast_init is called before usb_blaster_pin is evaluated. > > The pre-April 14 code didn't send those 4096 bytes. It generated setup > > USB packets that told the FT245 to discard all data in its FIFOs. > > Why has that part of the initialization been removed? > Ah, that's because the cheap clone based on Cypress chips doesn't honor the > setup packet to empty the FIFOs. I had decided to use something that would > work > for both the true Altera USB-Blaster and for the cheap clones. > > Now, we can differentiate in the configuration file between clones and true > Altera chips, and choose the specific Altera command to empty the FIFOs. Or > find > a way with the 4096 write to do it for both the clones and the originals. I'd > rather have something common for both of them, but if you convince me that > this > regression is unbearable, we'll patch to have the original behavior back. It probably doesn't matter if the FIFOs are flushed using that FTDI command. The only effect is that it might shorten initialization by a few milliseconds if the user managed to restart OpenOCD before the FIFOs emptied themselves. Best regards, Daniel ------------------------------------------------------------------------------ Is your legacy SCM system holding you back? Join Perforce May 7 to find out: • 3 signs your SCM is hindering your productivity • Requirements for releasing software faster • Expert tips and advice for migrating your SCM now http://p.sf.net/sfu/perforce _______________________________________________ OpenOCD-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/openocd-devel
