OMAP3503 MPU Watchdog reset leads to MMC1 data pins to level high?

Tianhua Chu

Just noticed that by letting MPU watchdog reset happen to generate a global warm reset, the data pins (dat7 e.g.) was driven to high (1.8v) slowly.

Anybody has an idea?

Thanks,

Philip

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Hi Philip,

Do you have external pullups on MMC1 lines? If you have, this could be the explanation, because these pins are 3-state with internal pulldown enabled at reset release time.

0 Tianhua Chu over 12 years ago in reply to Biser Gatchev-XID

Intellectual 560 points

Thanks for your reply.

We don't have an external pullups on MMC1 lines, and we have a 1.8v input to vdds_mmc1 from the PMIC and a 3.3v directly from the power supply.

If it does a cold boot, the mmc1_dat7 pin goes to high then immediately will be pulled down to ZERO, but with a watchdog timeout warm reset, the mmc1_dat7 high as 1.8v lasted for around 10 seconds.

Before the watchdog reset, mmc1_dat7 is configured as a GPIO_129 and set to low.

Thanks,

Philip

0 Biser Gatchev-XID over 12 years ago in reply to Tianhua Chu

TI__Guru**** 393215 points

Hi Philip,

I don't understand how can you have both 1.8V and 3.3V at the same time on the MMC power rail. Can you explain? What is connected on MMC1 interface?

0 Tianhua Chu over 12 years ago in reply to Biser Gatchev-XID

Intellectual 560 points

Hi Biser:

We have 1.8v connected to vdd_mmc1, and 3.3v connected to vdd_mmc1a (vdd_sim). And the MMC1_DAT7 is powered by vdd_mmc1a.

Thanks,

Philip

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OMAP3503 MPU Watchdog reset leads to MMC1 data pins to level high?