[U-Boot-Users] BDI2000 and MPC8260

[Jerry Van Baren <gerald.vanbaren@smiths-aerospace.com>]

Rune Torgersen wrote:
>>-----Original Message-----
>>From: Wolfgang Denk
>>Sent: Thursday, September 01, 2005 10:50
>>In message 
>><20050901111214.457804dc.ajz@cambridgebroadband.com> you wrote:
>>
>>>The problem I am seeing is that the bdi2000 cannot 
>>
>>communicate with the PM828 if the HRW is not
>>
>>>present in the flash device.  I.e. you need u-boot.bin 
>>
>>already loaded into flash in order to load
>>
>>>u-boot.bin into flash!
>>
>>This is normal; with an erased flash, the processor will read a  HRCW
>>which  sets external bus arbitration and CPU core disabled - there is
>>nothing left for the BDI to communicate with.
> 
> 
> We have anoter solution working here. To initally program the HRCW into
> flash we use another JTAG device (a Corellis JTAG interface) to wiggle
> th pins on the 8260 to program the flash. This works, but is fairly
> slow. To program 256 bytes of HRCW takes 10 - 15 seconds.
> 
> After this we switch to BDI2000 and program U-Boot.
> 
> This way we don't need yet another piece of HW on the board.

You realize of course that the HRCW is in the first 32 bytes of flash 
and you actually only need 4 bytes (offsets 0,8,16,24).  If you 
optimized your load, you could get the 10-15 seconds down to probably 1 
second.  Since it only needs to be done once in a board's lifetime, this 
may be a "don't care."

Other thoughts:
* Has anyone ever asked Abatron for an ability to use it as a raw JTAG 
accelerator?  It should be unnecessary to have a separate Corellis JTAG 
accelerator to do this.

* Freescale seems to have stopped providing unfettered access to the 
BSDL (Boundary Scan Description Language) interface to their processors. 
  For instance, the MPC8260 is not in the list:
<http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=0162468rH3bTdGZj9NtRjM>

* JTAG can be bit-banged with a PC parallel port extremely cheaply 
although it is also very slow.

gvb