From: Ville V. <vil...@kp...> - 2008-04-29 09:46:57
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> Yes it's part of the standard that TRST is optional, you can just sit > there with TMS high for five clocks from anywhere and get a reset. JTAG > is one of the few standards I actually paid money for and have on my > shelf :-) Bad news is that not all device manufacturers are as educated as you :) And then there is the additional problem of resetting the device vs. resetting the JTAG TAP. Even if you can reset the JTAG TAP, you may not be able to reset the device. I think many OpenOCD users have some experience on devices refusing to reset. > There's a third option, the MSP430 has a ROM bootloader we can > communicate with using a UART. Then the timing for flash actions is > taken care of then by the firmware. Yeah, but then you need an extra cable and another USB adapter, and that's sooo ugly... Of course, this is a matter of resources. If you want to make something future-proof, then I'd put my money either on writing MSP support for OpenOCD (which may or may not be difficult) or SVF (which splits the trouble into two). I know both of these are potentially time-consuming tasks, but both of them would be very useful, as well. --- I took a brief look into: http://focus.ti.com/lit/an/slaa149d/slaa149d.pdf (especially section 3.4). The flash programming algorithm is very straightforward and lends itself decently to SVF. The only worrying thing is that the JTAG frequency must be 350+-100 kHz, which may be a difficult specification to meet with some programming HW. I do not know if this can be overcome by specifying the time in milliseconds instead of cycles and only setting the maximum frequency. Probably, but I cannot say for sure. --- BTW, you don't have any space for an extra FT2232 on the board, do you? That way you coud get both the serial and the JTAG from a single USB connection. - Ville |