Which image are you using on your Edison?
The mem and freeze states are not currently working so you will not have a consistent behavior while using these states.
Are you using the 8,10 and 12 pins?
The pins will be active because the module is still being powered. Let us know which is the objective of getting a 0V in the pins so we could think in a different approach
Thanks for reply.
We are using our own version, based on latest git-repo of Yocto OS generated by bitbake.
"mem" mode works reliable on our custom board as soon as wifi is deactivated and image is patched as mentioned here https://communities.intel.com/thread/61067?start=15&tstart=0. We use MCU subsystem to frequently wake up our system, which works properly as well. Maybe in next official Yocto release mem-mode feature workaround could be taken into account, so the whole community can take advantage of it?
Yes, you´re right, we use pin 8,10(3.3V) and pin 12(1.8V) to supply some peripherals (level-shifter, MMC, MUX...). I prefer the current situation (1.8V/3.3V active) in mem mode.
I just want to make sure, that this is the correct behaviour and no bug, as I have to redesign our board and I have to take this into account.
The Edison module contains a power chip from Texas Instruments. The Atom processor is an independent unit.
You supply it with 4V and get 1.8V, 3.3V, etc.
The chip is programmed via I²C.
In order to shutdown the output of the power chip, you have to send special I²C commands, not just move the Atom into the power-saving mode.
But you don't want to do that because the Atom processor and the memory chip can't work in the power-saving mode without electricity: 1.8V and 3.3V.
Thanks to all for clarification.
As you mentioned, PMIC chip can be programed via I2C. Could you please give me some help to do it ?
Thank you very much
The PMIC SNB9024 is controlled and programmed by the SoC using the I2C lines, but there is no direct access to these lines. In order to modify the behavior of it you can use patches while building a new image.
There is a nice workaround I think it would help you, take a look at the following thread: https://communities.intel.com/message/379560#379560
I hope this helps.
Thanks for your reply
I read this thread but it doesn't have any information related to controling PMIC using I2C.
The Edison Module has two I2C interfaces, I2C1 and I2C6. If you are using the Edison Compute Module you can have access to both of them but if you use the Arduino Expansion Board you only have access to one of them due to the other one is connected to the ADC of the board. http://www.intel.com/content/dam/support/us/en/documents/edison/sb/edison-module_HG_331189.pdf
The PMIC is programmed via I2C, but there is no access to these lines. https://communities.intel.com/thread/104104