[gta02-core] -1 Hardware revision stored in EEPROM

Álvaro Lopes alvieboy at alvie.com
Thu Aug 27 21:43:19 CEST 2009

Rask Ingemann Lambertsen wrote:
> On Wed, Aug 26, 2009 at 09:19:31PM +0100, Dave Ball wrote:
>> Álvaro Lopes wrote:
>>> I must confess I agree in priciple.... but this presents some other problems - it has to be programmed either before or after assembly.
>>> And we do not use most of CPU pins, so we can use them just for now. 
>> I agree.  I personally like having real HW revision detection so it's 
>> easy to change the board revision if/when mods are made to each of the 
>> prototypes with solder blobs, and visually confirm the revision.
>    How about using the analog inputs ANx instead? We can encode several bits
> per pin that way. Some of the SMD packages are large enough that resistor
> values are printed on them.

If we discard the lower (error-prone) bits I think we can do it that way, yes...

>> Maybe we should move it to GPA17/18 to avoid the EINTs, but we only 
>> really gain if we end up using those EINTs for something else...
> [...]
>> I've not dug into the datasheet, but would doing something with gpa0-8 
>> be less risky?
>    From the datasheet: "Port A(GPA): 25-output port".
>> Freeing up the camera port for IO might be nice, but I think I'd rather 
>> leave those lines as they are in gta02.  Less mistakes for us to make!
>    Then the gta02-core will be completely uninteresting for hardware
> hackers. Notice how few DIY hardware projects have been made for the GTA01
> (after two years) or the GTA02 (after one year) - really just Werner's IDBG.
> That's simply because they offer so little in the way of interfacing
> hardware addons. This is a mistake I would like gta02-core to avoid.

Understood, and agreed.

>    For an example of the problems DIYers are facing with the GTA02, at least
> two people have looked into adding a camera to a GTA02[3] and half a year
> later they haven't succeeded. That's disappointing considering that a 1.3
> Mpix camera module costs less than $10 [4] and has a relatively simple I2C +
> 8-bit parallel interface.

I wonder if we should get all unused pins in some FPC connector.... cost would not be so high, would it ?


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