On Wednesday 23 September 2009, Michael Schwingen wrote: > David Brownell wrote: > > Where -- to summarize ruthlessly -- you said that not only is > > the FT2232 annoyingly imposing an SRST on you, but you also > > need an extra delay to recover from that. Right? > > > A board may stretch SRST, so you *have* to be able to wait a > (user-defined) amount of time after SRESET assertion/deassertion before > talking to anything in the chain. This is also true if the SRESET > assertion is not caused by OpenOCD directly.
Understood. This is part of why some JTAG adapters provide inputs for SRST, not just outputs. It'd be nice if the FT2232 ones provided a "USB interrupt" to give hosts an asynch (more or less) notification that it was asserted. Hmm ... FT2232 *does* have special 0x88 and 0x89 commands to block on ACBUS1 (GPIOH1) levels. And at least one adapter design I'm looking at hooks nSRST up to that, as an input (you can tell by, among other things, looking at how the level shifters are wired). So for such adapters (which I suspect aren' that common) it might be possible to add some special casing to handle that case. - Dave _______________________________________________ Openocd-development mailing list [email protected] https://lists.berlios.de/mailman/listinfo/openocd-development
