[U-Boot-Users] debugging u-boot

[Ben Warren]

On Fri, 2006-10-20 at 10:55 -0400, Lei Sun wrote:
> Hi all:
>   I am trying to bring up a custom designed board based on MPC8270,
> after spent 3 weeks on fixing hardware issues (extreme surgery !) , I
> finally be able to read something out of the flash and verified SDRAM
> is working as well. Up to this point our JTAG debugger is dead! I
> burned u-boot Image using a programmer and put it in. after power up
> and did a PORESET, I found out that every 20 seconds or so , system
> generated HRESET,( by measuring the HRESET pin of the JTAG port). It
> does read Hardware Reset Config Word when reset happens (I saw pulse
> on the CS0 pin).  Before the JTAG die, i was able to issue "reset"

Just because CS0 pulses, it doesn't mean the RCW was read successfully.
Look in your CPU's manual, but I think the 20-second periodic reset
means it wasn't read properly.  Check that your local bus interface to
the flash is identical to a known working design, for example the
Freescale evaluation boards (Schematics should be available on their
website).  Pay close attention to the LS address bits, which, at least
on the MPC8349, should use the dedicated address signals (LA27-LA31) and
not the muxed ones(LAD27-LAD31).  Again, check against a reference
design just to be sure.

> 2. Any good JTAG debugger for this family of CPU you can recommend ?
As others have mentioned, the Abatron BDI-2000 is excellent.

regards,
Ben