GTA02 MPU alternatives

Werner Almesberger werner at
Fri Apr 25 17:26:16 CEST 2008

I wrote:
> 1) if we connect the JTAG chain improperly, JTAG will not work at all

I forgot to mention one way that was proposed to contain this issue:

We could add 0R or NC resistors to allow the system to be configured
with only the MPU in the JTAG chain or with only the CPU in the JTAG

In my opinion, if we're already afraid of breaking something by just
making the chain, how much riskier would it be to have to design two
alternative chain configurations ? So I think this is a foul compromise
that only increases the risk of something going wrong.

If we're really really nervous about this, we could put a 0R in each
JTAG line that goes to the CPU, so that the CPU can be isolated and a
JTAG interface could be attached with wires.

But as I said, I think we should just not be paranoid about this.

- Werner

More information about the hardware mailing list