Hello everyone,
I have a question regarding the power on/off control on the ixora carrier board.
I did some tests and measurement on IC3 and IC4 (see screenshot). when powering the system ON with the power on button everything is working an booting fine, same when powering the system OFF with the button.
When doing a software reboot in linux ($ reboot) I can see a small drop of 10ms on POWER_ENABLE_MOCI and a drop of 6sec on RESET_MOCI. And here is my first question.
with RESET_MOCI going down for such a long time, it should switch off IC4. but this does nothing to IC3 KILL# because of the pull-up resistor. but when RESET_MOCI is coming back up again, IC4 is switch on again but there is the same voltage on IC4-A and IC4-Y so that’s weird. (So here, the software reset works fine)
Secondly, when I do a software shutdown on linux ($ shutdown now) the 5V_SW and 3.3V_SW are turning off because POWER_ENABLE_MOCI is coming down. But, as you can see, IC4-A and IC4-Y are powered by 3.3V wich is still alive at the moment. RESET_MOCI is down. But as explained earlier, IC3-KILL# is not coming down because of 3.3V. So here is the problem, the Apalis module is still powered by the 3.3V too. And so, to re-boot the system, I have to press twice on the power on button, once to kill PWR_EN# and once to power on the system.
I have think of a solution to that and I would like to know if that is feasable. Firstly, I would use POWER_ENABLE_MOCI instead of RESET_MOCI on IC4_OE (my only concern is that POWER_ENABLE_MOCI comes down for 10ms when rebooting and I don’t know if this would kill the power supply). Secondly, I would use a pull-down instead of a pull-up on IC4-Y, and remove the pull-up on IC4-A and directly put IC4-A to 3.3V
So I hope I explained my problem well and that you can advise me.
Thanks
PS: All of the testing and behavior explained here are done on the ixora carrier board and the push button controller schematic comes from the ixora schematics : Ixora Carrier Board | Toradex Developer Center