Hi,
I'm using OMAP3530 with TPS65950.
It seems that PMU VDD1, VDD2, VIO and VPLL1 power supply outputs are fine.
Also HFCLKOUT and 32KCLKOUT outputs are fine.
For some reason nRESPWRON output remains low keeping OMAP3530 in reset.
What might be the problem?
Thanks.
Is the nRESPWRON signal directly connected between OMAP and the PMIC?
Does this happen on all your boards? Please ensure that there is no pull-down or something else that would keep the signal low at all times.
Regards,
Gandhar.
Regards,Gandhar------------------------------------------------------------------------------------------------------Kindly click the Verify Answer button on this post, if it answers your question.------------------------------------------------------------------------------------------------------
Hi Gandhar,
Thank you for your quick response.
The nRESPWRON signal is connected directly from PMIC via 33ohm serial resistor to OMAP.
We have checked first 3 boards and it does happen on all of them.
There is no pull-down on nRESPWRON line (only 33ohm serial resistor between two devices).
I see now that nRESWARM coming from OMAP is low. nRESWARM signal has a 10Kohm pull-up to 1.8V so it looks like OMAP is keeping it low.
What might be the cause of this behavior?
Igal
You dont need to have a 33ohm on this signal. It will work fine without that as well.
Here is what might be happening:
When you power-up the platform, it does power up completely. Probe the nRESPWRON continuously (maybe trigger mode) to see that it would go high. This would power on the OMAP. Now when OMAP executes it power-up or boot-up sequence it would be executing the warm-reset sequence as well. You can search for the warm-reset sequence in the code. I dont know where exactly it would be. Try the TPS65950 or TWL4030/5030 drivers, you will find it there.
When the OMAP sets the warm-reset low then this initiates the programmed warm reset sequence in TPS65950. I think the warm reset code is active hence you see this behavior. OMAP should start this only when it is needed. I am surprised that other power levels are ok. If the warm-reset is executed then these also shoul dbe low. It really depends on what is programmed in the sequence. This is a user defined sequence. Let me know if you have programmed it or if you are using some code base from open community?
You may be able to power up the platform by pressing the PWRON switch (if you have one). However, this cycle will continue. So, the best way is to first confirm that nRESPWRON does go high and OMAP comes out of reset. You can also probe warmreset to check if it transitions from high to low after OMAP boots up.
Lets start from here and see if my analogy is correct.
do you recommend an additional pull-up for NRESPWRON?
Regards, Thomas
Would still like to know about the pull resistor...
10k pullup added, works fine