Re: Searching for JTAG Flash Programmer for ARM7 and AT29c040a

From: Tauno Voipio (tauno.voipio_at_iki.fi.NOSPAM.invalid)
Date: 03/17/04 

Date: Wed, 17 Mar 2004 18:08:42 GMT

Daniel wrote:
> Dear all,
>
> thanks for the replies.
>
> Conclusion:
> 1. Method
>
>>>> - a program able to write the Flash from the RAM
>>>> - the program destined for the Flash
>>>>
>>>>After loading both pieces, I start the writer with
>>>>the JTAG interface and let it do the programming.
>
>
> This does not help for programmes which need more space than internally
> available. My MCU has 16 KB internal RAM. This is not sufficient.

Transfer the code in slices. The Flash writer is less than
2 kbytes, so you should be able to have e.g. 12 kbytes slices.

The Flash programming algorithm is quite on the complicated
side to be performed from JTAG directly.

To refresh the memory: the JTAG RAM write procedure:

  - load a LDMIA instruction into the pipeline
  - load some NOP's to get to the execution cycle
  - load the data for the LDMIA
  - load a STMIA instruction in the pipeline
  - execute the STMIA at full speed to access the memory
  - stop the processor
  - repeat loop till done

Add the Flash write sequence requirements to the above,
so you'll see why it's not recommended (yes - it should
be doable, never tried such a kludge).

Been there - done that.

Tauno Voipio
tauno voipio @ iki fi

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