I2C Regulator reprogramming

[tnt]

Hi,

I was wondering where the reprogramming of the I2C regulator was happening ?

For the rev1 the default voltages are a bit on the high side
- 1.2v for the epiphany while it should be 0.9v - 1.1v
- 1.5v for the DDR3 while nominal value is 1.35v

But since you need to shutdown the regulator output to reconfigure, if you want to change the DDR voltage, that needs to be done _very_ early, before RAM is even initialized ... (so like fsbl ? or is u-boot initializing the ram controller)

Cheers,

Sylvain

[aolofsson]

I2C reprogramming is currently done in uboot.
Andreas

[tnt]

I guess it's not yet in any published code ? Because I don't see it.

[aolofsson]

Just published the code...
https://github.com/parallella/parallell ... e4529e0f14

Andreas

[tnt]

Mmm, that's probably too late to change the DDR voltage. It would need to be done in low_level_init before it switches to C I think. (I think when it switches to C it expects RAM to be up).

[aolofsson]

Boards finished assembly today (slight delay..). We'll let you know how things go at power up. Agree that a safer avenue would be to change the DDR voltage without reading from DRAM, but a gradual drop from 1.5V to 1.35v should work..