Interface signal questions for Overo COM boards

[Clyde Hinkle]

#1) Is the Vsystem signal on J5 a direct connection to the Vsystem signals on J1/J4?

#2) Do all the Vsystem pins, on J1 and J4, go directly to the PMIC "Vbat" regulator inputs as shown in Figure 4-1 of the TPS65950 datasheet and all the Vbat* named signals from Table 2-2?

#3) J1 pin 65 is labeled POWERON but it didn't look like it was used on the Tobi or Summit expansion boards. Per the TPS65950 datasheet (Table 2-1) this signal is referenced to the VBAT power input on the TPS65950 and had no internal pullup. So does it have a pullup to Vsystem on the Overo COM?
 
#4) J4 pin 41 is labeled GPIO114_SPI1_NRQ. I don't see SPI NRQ as an OMAP defined function. So that is just OMAP GPIO114 and can be used for other GPIO purposes, right?

#5) J1 pin 1 is labeled N_MANUAL_RESET. Does that go to the NRESWARM pin on the PMIC?

Thanks

 

C W Hinkle

Ascendant Engineering Solutions

Austin, TX

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[R. P. McMurphy]

On 10/3/09, Clyde Hinkle <[hidden email]> wrote:
> #1) Is the Vsystem signal on J5 a direct connection to the Vsystem signals
> on J1/J4?

Yes.

> #2) Do all the Vsystem pins, on J1 and J4, go directly to the PMIC "Vbat"
> regulator inputs as shown in Figure 4-1 of the TPS65950 datasheet and all
> the Vbat* named signals from Table 2-2?

Yes.

> #3) J1 pin 65 is labeled POWERON but it didn't look like it was used on the
> Tobi or Summit expansion boards. Per the TPS65950 datasheet (Table 2-1) this
> signal is referenced to the VBAT power input on the TPS65950 and had no
> internal pullup. So does it have a pullup to Vsystem on the Overo COM?

IIRC this pin is an output from a master PMIC chip so no pullup is needed.

> #4) J4 pin 41 is labeled GPIO114_SPI1_NRQ. I don't see SPI NRQ as an OMAP
> defined function. So that is just OMAP GPIO114 and can be used for other
> GPIO purposes, right?

Yes.

> #5) J1 pin 1 is labeled N_MANUAL_RESET. Does that go to the NRESWARM pin on
> the PMIC?

I am not sure about this one, but yes that is most likely. Lowering
GPIO30 will also reset the board.

> Thanks
>
> C W Hinkle
> Ascendant Engineering Solutions
> Austin, TX

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[Søren Steen Christensen]

> > #3) J1 pin 65 is labeled POWERON but it didn't look like it was used on
the
> > Tobi or Summit expansion boards. Per the TPS65950 datasheet (Table 2-1)
this
> > signal is referenced to the VBAT power input on the TPS65950 and had no
> > internal pullup. So does it have a pullup to Vsystem on the Overo COM?
>
> IIRC this pin is an output from a master PMIC chip so no pullup is needed.

In case we are speaking about the PWRON pin on TPS65950 (I assume we are),
this is always an input and referenced to VBAT as described in the original
post. In case the pull-up isn't mounted on the Overo module itself you would
need it externally on your own board.

I would however assume it's mounted on the Gumstix (but I don't know) since
it's working and since a low going pulse on this signal will switch on the
board after it has been switched off.

Can anybody from Gumstix please comment on this?

Best regards and thanks
  Søren

---
SSC Solutions ApS - Denmark - www.ssc-solutions.dk



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[Ken Gudan]

I am experiencing infrequent power up problems with Overo Air modules.  10% of my systems will fail to boot after a week of use.  The problem is the PMIC not turning on power to the OMAP.  I am floating PWRON on my main board, per some of the previous discussion here.  I posted this question to a TI OMAP forum, and received this answer today from Gandhar who is active on the TI site:

"Do you not connect anything to PWRON? Floating SYSEN output is ok.
 
PWRON should be connected to VBAT via a switch or via pull-up. It should not be left floating. You will surely have issues due to this."

I'm going to add a pullup to PWRON, but this problem is so infrequent, it will be difficult to tell if this fixes anything.  If someone from Gumstix can confirm if PWRON is pulled up on the module, that would be very helpful, so I'm not guessing anymore!  Thanks.