AM3358-EP: How to change the status of F17 pin on power up

Gaurav Aggarwal

Part Number: AM3358-EP

Hi!

I am using Sitara AM3358BGCZA80EP with processor_sdk_rtos_am335x_6_01_00_08. I have configured F17 pin as PWM to control the brightness of Led. As this pin is active pull up on power up so due this by default led is glowing but I need low condition on power up. Kindly suggest any solution to to this so that it should not affect the functionality.

If I make external pull down then voltage will get divide and it will affect the brightness.

As this pin includes functionality of MMC_DAT3 so if I include MMC in booting list, will it become low by ROM bootloader.

SYSBoot[4:0] = 10011b;

Regards,

Gaurav

over 3 years ago

0 Aravind Batni over 3 years ago

TI__Expert 8885 points

Hi Gaurav,

I am checking on this internally to get back to you. Please note, the response may be delayed.

0 Gaurav Aggarwal over 3 years ago in reply to Aravind Batni

Expert 2935 points

Hi Aravind

Please check and let me know.

Regards,

Gaurav

0 Jianzhong Xu over 3 years ago in reply to Gaurav Aggarwal

TI__Mastermind 40215 points

Hi Gaurav,

You can use the Pinmux tool to choose a pull up or pull down for pin F17. Please see example below.

Regards,

Jianzhong

0 Jianzhong Xu over 3 years ago in reply to Jianzhong Xu

TI__Mastermind 40215 points

Sorry, the picture wasn't attached. Reattach it.

0 Gaurav Aggarwal over 3 years ago in reply to Jianzhong Xu

Expert 2935 points

Jianzhong,

I have already done pull down. But problem is after booting only it will execute so for some short duration this pin will remain high. My client needs it should be low immediately after power on.

Regards,

Gaurav

0 PaulM over 3 years ago in reply to Gaurav Aggarwal

TI__Mastermind 23035 points

Gaurav

The reset and post reset configuration of the pin is fixed until it can be programmed by software or, is touched by the ROM bootloader.

The only option is to move to a different pin or invert the LED control circuit so that it is on high. As you noted above, you will need to consider if the pin configuration is changed by the ROM bootloader. Pin D14 or B13, (ZCZ Package) could be possibilities. There are others. Check the device datasheet table 4-2 for details on each pin reset configuration.

--Paul

0 Gaurav Aggarwal over 3 years ago in reply to PaulM

Expert 2935 points

Paul,

Thanks for your help.

My problem is resolved.

Regards,

Gaurav

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AM3358-EP: How to change the status of F17 pin on power up