i.MX Processors中的主题 Re: Request for Guidance on Modifying Display Power Rail Voltages in GMT2194 PMIC for E Ink Panel on

Request for Guidance on Modifying Display Power Rail Voltages in GMT2194 PMIC for E Ink Panel on i.M

Radhika_changela — Mon, 12 May 2025 13:50:28 GMT

We are currently bringing up the E Ink paper display on the x-8ULP-ACEP-EPD board. We are using the GMT2194 PMIC to manage the display power subsystem.

We need to modify the display power rail voltages to match the supported voltage range of the display. Specifically, the display requires -15V, but the PMIC is configured by default to output -17V.

We are using the following:

Device Tree Source (DTS) file: imx8ulp-acep.dts
PMIC driver source: gmt2194-core.c

Could you please guide us on how to change the PMIC regulator voltages accordingly?

Re: Request for Guidance on Modifying Display Power Rail Voltages in GMT2194 PMIC for E Ink Panel on

JorgeCas — Mon, 12 May 2025 18:16:16 GMT

Hello,

The G2194 PMIC board was designed by GMT and EINK please put in contact with them for further support.

Unfortunately, we do not have access to the source code.

Best regards.

Re: Request for Guidance on Modifying Display Power Rail Voltages in GMT2194 PMIC for E Ink Panel on

Radhika_changela — Tue, 13 May 2025 05:02:20 GMT

Hi,

Thanks for the update.

Is there any way to set this voltage through the device tree file?

As we don’t have direct contact with GMT, it would be great if you could help us with this.

Re: Request for Guidance on Modifying Display Power Rail Voltages in GMT2194 PMIC for E Ink Panel on

Chong — Wed, 21 May 2025 07:52:10 GMT

Hi @Radhika_changela ,

Can you provide all the voltage rail values you require?
I can help and change it.

Best regards,
Chong

Re: Request for Guidance on Modifying Display Power Rail Voltages in GMT2194 PMIC for E Ink Panel on

Radhika_changela — Wed, 21 May 2025 10:02:55 GMT

Hi @Chong ,

I am using the E Ink ED103TC2 E-Paper display, and the following power rail voltages are required for proper operation:

VPOS3 = 28V
VPOS2 = 15V
VNEG3 = -20V
VNEG2 = -15V

Best regards,
Radhika_changela

Re: Request for Guidance on Modifying Display Power Rail Voltages in GMT2194 PMIC for E Ink Panel on

Chong — Fri, 23 May 2025 01:56:26 GMT

Hi @Radhika_changela ,

You can try the following settings in drivers/regulator/gmt2194-regulator.c

unsigned short VNEG1_HEX = 0x0514;
unsigned short VPOS1_HEX = 0x0514;
unsigned short VPOS2_HEX=0x69B
unsigned short VNEG2_HEX=0x69B
unsigned short VPOS3_HEX=0x389
unsigned short VNEG3_HEX=0x20C
unsigned short VCOM_HEX = 0x0948;

Best regards,
Chong

Re: Request for Guidance on Modifying Display Power Rail Voltages in GMT2194 PMIC for E Ink Panel on

Radhika_changela — Tue, 27 May 2025 06:52:24 GMT

Hi @Chong

Thank you for the support.

My PMIC generated required output voltages hex value in driver file.

Best regards,

Radhika_changela