> > It's a 20 pin chip, and you want to use four of them for JTAG? > I thought I saw you were looking at doing something with an ARM9 chip.
JTAG is only fully useful when all the chips support it - you'd chain all the chips together to do continuity testing of the board after assembly. The R8C/17 doesn't support JTAG. I think ARM9 chips expect you to use JTAG for downloading and debugging, yes.
