JTAG and the Echostar AD3000

[Llew]

Maybe I'm wrong, but received opinion on this and other forums suggest that jtagging the AD3000 to access the EEPROM is not possible. Usually, in cases where the EEPROM is corrupt, the box must be sent away for repair, or the chip removed and either replaced, or as I understand it, erased and loaded with a working dump file.

I have now jtagged the CPU and can read the registers. The IBM CPU's core is a ppc401d2. The JTAG connector uses the 16-pin layout for this core, and I pinned the board's JTAG pads with 2x 8-way header plugs.

This enabled me to interface with a Raven programmer, using the free Magraigor OCD Commander programme.

I now need to access the EEPROM (an Atmel 49BV1614) through the CPU, but this is not trivial, as the JTAG software I have at the moment returns various errors when trying this.

This project is really just for my satisfaction, but if it is possible maybe it will remove the need for taking the chip out if it can be reprogrammed 'through the back door' so to speak.

Llew

 

[Topper]

That sounds interesting Llew, I don't have the patience for such investigations myself, it does sound as though you may succeed where others have failed

I do not know what info you have Llew but this document has some detail about the hardware reset pin 12 on the Atmel 49BV1614

 

[Llew]

Yes thanks Topper, I'll add that to my files. All operations on the chip should be able to be performed through the CPU, I just need to get the CPU to 'see' the EEPROM first. My JTAG software recognises the Atmel chip, but as I say errors occur when trying to read through the CPU.

Llew