27 Oct
2011
27 Oct
'11
6:34 p.m.
Chuck Guzis wrote:
Microchip is a very strange outfit when it comes to
the PIC32. Like
the R4000, programming on the PIC32 is present as JTAG. However
Microchip incorporated a rather convoluted version of their SPI
protocol that's translated into JTAG on the chip. I'm sure it sells
a lot of PICKIT programmers, but otherwise, it's been a mystery to me
why this was done. Could it be that JTAG is more or less industry
standard for this sort of thing?
JTAG is a serial protocol that communicates to one or more chips on a JTAG
bus. It is commonly used as the debugging vehicle for some CPU families.
It communicates between a host computer and the debug subsystem within a
target CPU to allow:
1. Run-time debug and breakpoint operations.
2. Boundary-scan that lets you emulate the CPU for the outside circuit.
3. Flash programming since it can be used to generate memory bus cycles.
Vendors often use proprietary serial mechanisms for their pods and JTAG
functionality. I would presume this is to make sure you buy their tools.
Amardeep