GPIO State in suspend on DM3730

valeswararao

Other Parts Discussed in Thread: TXS0108E, TXB0108, DM3730

Hi all,

I am facing issue with gpio in suspend. As per logic, I am using gpio to control the power status of the device and gpio was going through the level shifter. we are configuring the gpio value to low (0) and when system goes to suspend gpio value changing to high(1). but as per description gpio should stay in in low level.

Please give suggestion for working this issue.

Thanks & Regards,

Valeswararao

over 12 years ago

0 Cvetolin Shulev-XID over 12 years ago

TI__Guru 65405 points

Hi Valeswararao,

Could you give more details about the issue and environment? Which GPIO you are using. What about pinmux configuration for this GPIO. Some details about OS.

Tsvetolin Shulev

0 valeswararao over 12 years ago in reply to Cvetolin Shulev-XID

Prodigy 60 points

Hi Tsvetolin Shulev,

Issue: Gpio value is changing in suspend mode.(system is completely suspended VDD1 and VDD2 is off). environment is DM37xx based custom board.

I am using gpio 149, for pad muxing we are configuring 0x204 in the 16bit of the gpio_149 pad.(Writing 0x2040000 in 0x4800217c register).

Please check the attached image for connection details.

Thanks & regards,

Valeswararao

0 Biser Gatchev-XID over 11 years ago in reply to valeswararao

TI__Guru**** 393215 points

Hi Valeswararao,

Can you give the part number of the level shifter?

0 Srinivas Marakala1 over 11 years ago in reply to Biser Gatchev-XID

Intellectual 560 points

Hi Biser,

Vali and I are working for same project.

We are using TI part TXS0108E - 8-Bit Bidirectional Voltage-Level Translator for OD and Push-Pull Applications.

The problem might be due to the Pull Up/Down registers inside Level shifter and on OMAP GPIOs (during suspend). We want to know how do we avoid this problem.

Thanks,

Srinivas

0 Biser Gatchev-XID over 11 years ago in reply to Srinivas Marakala1

TI__Guru**** 393215 points

You are right, TXS0108E has internal pullup resistors on both sides. TXB0108 is a pin to pin compatible part that does not have these pullups.

0 Srinivas Marakala1 over 11 years ago in reply to Biser Gatchev-XID

Intellectual 560 points

Thanks for the quick response Biser.

Do you suggest that we should use TXB0108 level shifter to avoid this problem? Is there any option on OMAP side? We are seeing this problem in other instances where external pull up resistors are present on the signals? Are there any recommendations from TI on Pull Up/Down resistors on GPIO signals? Can we do something with pad muxing options to avoid this problem?

Thanks,

Srinivas

0 Hongtao Yan over 11 years ago in reply to Srinivas Marakala1

Intellectual 395 points

Let me reiterate this issue:

We are configuring the register CONTROL_PADCONF, set the following bits:

OFFENABLE = 1 ; Off mode enable

OFFOUTENABLE=0; Output enabled during off mode

OFFOUTVALUE=1 = 0 ; Output value0 during off mode

When the DM3730 get into suspend mode, this pad should get into OFF state. PAD should be driven the value we set in the OFFOUTVALUE. But we found that instead of being driven, the pad is actuall pull low. So the external pull up could override the pad value. This is why the level shifter pullup affect the pad state, causing unexpected glitch on the level shifter output side.

Question: Why the pad is not being driven during the off mode? Is there something missing in the programming sequence?

0 Hongtao Yan over 11 years ago in reply to Hongtao Yan

Intellectual 395 points

Could someone from TI help to answer this issue? We need a solution before we can re-spin the hardware.

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GPIO State in suspend on DM3730