Issues setting TPS65154 voltages with device tree overlay for custom cape and LCD on BBB

Embedded Linux Discussions
1

Hi, I am currently working on a project to build a custom cape and lcd display for a BeagleBone black.

The cape design uses a TI TPS65154 LCD Bias IC with Integrated WLED Driver and a Zenyo 1024 x 600 TFT-LCD.

tps65154.pdf (2.8 MB)
ZenyoLCD.pdf (993.2 KB)

When I measure the voltage outputs of the PMIC, I see that they were set to their default values:

  • VGH: 20V (zenyo lcd recommended voltage: 17V - 19V)
  • VGL: -6.8V (zenyo lcd recommended range: -7V - -5V)
  • AVDD: 8V (zenyo lcd recommended voltage: 9.3V - 9.9V)

image

I’m trying to find a way, with not much luck, to see if I can program the PMIC output voltages to the following values in the Device Tree Overlay file.

  • AVDD: 9.6V
  • VGH: 18V
  • VGL: -6V
  • VCOM: 3.3V

Current Device Tree Overlay file:

BB-BONE-ZENYO-01-00A5.dts (7.2 KB)

I’m hoping someone could help point me in the right direction if this can be done here and is so how I would go about doing so.

Thanks in advance,
Scott

2

So problem number 1… Today i see there is no tps65154 support in mainline linux…

So, option #1 write a tps65154-regulator.c driver:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/regulator?h=v6.2-rc1

Option #2, looks like this device has an on board eeprom, which could be used to store your start up default voltages.

Sorry, no really easy answer as this device is not supported out of the box today…

Regards,

3

Thanks for the reply! Based on what I was seeing online that was what I was suspecting was the case. Though I would ask anyway.

Setting the voltages in the eeprom is what I’ve been doing to this point but for 1000’s of devices in commercialization I would before we can set it in the overlay. Looks like we may have to go with option #1.

Thanks,