i.MX ProcessorsのトピックRe: Display image from frame buffer /dev/fb0 to dual LCD i.MX8MMini

Display image from frame buffer /dev/fb0 to dual LCD i.MX8MMini

rkhatal369 — Tue, 27 Oct 2020 12:21:59 GMT

Hello Community,

We are using custom board based on i.MX8MMini. I am trying to display single image from frame buffer, to dual LCD via MIPI-DSI interface. Can you please tell me how can i display single image on dual LCD.

For LCD selection i used MiPi switch. Please see attached diagram. From frame buffer i take single image and i want to display half part of image on LCD_1 and another half part of image on LCD_2.

Thank you!

Best Regards,

Rohit

Re: Display image from frame buffer /dev/fb0 to dual LCD i.MX8MMini

igorpadykov — Wed, 28 Oct 2020 05:54:57 GMT

Hi Rohit

could you provide more details about dual lcd connection, as in attached diagram

there is no "MiPi switch". It is not possible just to connect two LCDs directly to MIPI-DSI module.

Dual LCD is easy to implement with i.MX8MQ connecting DCSS to HDMI and eLCDIF to MIPI-DSI.

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mq-evk-dual-display.dts?h=imx_5.4.47_2.2.0

However for i.MX8M Mini, which has not DCSS and HDMI I am not sure that it is feasible.

Best regards
igor

Re: Display image from frame buffer /dev/fb0 to dual LCD i.MX8MMini

rkhatal369 — Wed, 28 Oct 2020 06:28:52 GMT

Hello Community,

Please see below reference picture for LCD display.

I have to display image with half part on LCD_1 and another half part on LCD_2 like below picture.

We used mipi DSI and from frame buffer /dev/fb0 we want to display image on LCDs.

For LCD selection with higher rate (speed) we used MIPI switch.

Any suggestion, Documents will be helpful.

Thank you!

Best regards,

Rohit

Display image from frame buffer /dev/fb0 to dual LCD i.MX8MMini

rkhatal369 — Wed, 28 Oct 2020 07:38:18 GMT

Hello Igor,

Thank you for your reply.

Below are the LCD's connections details,

LCD_1 :

LCD_2:

MIPI Switch :

At a time only one LCD will be selected using MIPI switch. But switching would be fast so user will be able to see data on both the screens.

Below is the flow diagram,

From Frame buffer we have to take image and via MIPI DSI we have to passes that image. Using MIPI Switch We select one of the LCD at time and display that image.

I do not understand how to pass half part of image on LCD_1 and another half part on LCD_2 from frame buffer.

Thank you!

Best regards,

Rohit

Re: Display image from frame buffer /dev/fb0 to dual LCD i.MX8MMini

igorpadykov — Wed, 28 Oct 2020 07:50:37 GMT

Hi Rohit

are both LCDs identical ?

For frame buffer may be useful to look at unit tests:

https://source.codeaurora.org/external/imx/imx-test/tree/test/mxc_fb_test?h=imx_5.4.47_2.2.0

Best regards
igor

Display image from frame buffer /dev/fb0 to dual LCD i.MX8MMini

rkhatal369 — Wed, 28 Oct 2020 08:43:13 GMT

Hello Igor,

Thank you for reply,

Yes both LED's are identical.

Best regards,

Rohit