GTA02 MPU alternatives
OpenMoko at mauve.plus.com
Fri Apr 25 21:35:16 CEST 2008
Werner Almesberger wrote:
> Ian Stirling wrote:
>> I have a project based on ST micros cortex chips that bit-bangs SDRAM,
>> taking advantage of the block read function, and would in principle work
>> for keeping the LCD state when the CPU is off.
> That's nice ... but, could we perhaps start with a problem statement
> before the proposed solution ? I.e., what would this do that we want
> to do but can't or can only do with undesirable consequences ?
I was unfortunately rushed at the time, and probably shouldn't have
posted without more thought.
The thought was that the chosen MPU might be able to fulfull multiple
roles - amongst them being able to run the LCD of the GTA03/... when
off, being able to be used as an SD expander, providing the emergency
recovery facility, ...
On reflection - this won't work so well as I understand it, as the RAM
is inside the SoC - and adding external lines from the SDRAM to the MPU
would cause probable congestion.
Also - I hadn't fully considered the number of lines - the design I was
using was an 8M*8 SDRAM paired to a 8 bit display, which is considerably
fewer (around 40) than the would be required by the 32M*32 (presumably)
of GTA03, and voltages will likely not be a match.
I still think it's worth a look if a SD expander is also needed, though
I have not actually used the SD/MMC functionality on these chips, or
looked at it in depth yet.
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