Seeking info on the DSI/MIPI interface of STM32H747I-DISCO

[B_M]

I have the STM32H747I-DISCO, and am interested in connecting a larger touch display. What possibilities are there? What limit is there on display resolution? Could a 2560 x 1600 display be used for example (I do not need video. I just need larger physical format, higher resolution, and low frequency update in real time)? Where are the critical choke points on display resolution (apart from the obvious video memory)? MB1166? Elsewhere?

What about connectors? Firstly there is CN1 a 60 pin connector on the back of the LCD daughterboard MB1166 which plugs into CN15 on the main DISCO board - is this a standard MIPI connector or arbitrary to this device? Are there independently produced displays with a compatible connector? 

The LCD itself is connected, as far as I can see, by two flex cables, a 12 pin flex connector CN2 from the display and a 6 pin flex connector CN3 from the touch screen. Could CN2 and CN3 be potentially used by an alternate larger display in place of the existing display?

There are also two flex cables folded under the display on the top surface of MB1166 (one large - 60 pin?, and one 2 pin), I am guessing these are internal to the manufacture of the display itself. 

Is 60 pin a standard interface for DSI/MIPI? I note there are DSI/MIPI displays available on the market with a 60 pin ribbon cable. Is there information available on connecting such ribbon cables to CN15 on the DISCO board?

In the DISCO user manual UM2411 there is a pinout for CN15 (no other information), but I haven't found any other information so far.

[CYANG.1]

Hi,

The 60pin connector on MB1166 was defined by ST, so it was not a standard connector in the market. only ST daughter boards can be used on the connector.

For the flexible cables on CN2 and CN3, they were also defined by LCD vendor. It is not easy to find a compatible part unless you customize it from LCD vendor.

CN1/CN2/CN3 were all placed on the bottom side of MB1166. All signals from LCD (CN2-DSI signals, CN3-touch panel signals) were routed to CN1. Then all signals were connected to MCU on the board through CN1 (on MB1166) and CN15 on mother board.

Best Regards.

[B_M]

Many thanks for the partial reply CYang. 

Firstly on the connector: if I get a display with MIPI interface and make a custom ribbon to connect matching pin definition to matching pin definition does that have a resonable chance of scoring success, or is there another problem that might intervene here? MIPI is a proprietary interface and as far as I know does not release much information except to MIPI members (which ST is), therefore I am reliant on ST for such information.

Secondly on the display resolution, which you did not address yet - can MB1166 handle a 2560 x 1600 display resolution? What is the maximum resolution and pixel depth it can handle?

I am interested in using this display for example https://a.aliexpress.com/_c2IH6dJn

Thanks.

[CYANG.1]

Hi,

I don't know which connector you refer? the connector for LCD flexible cable or the connector for between MB1166 and mother board?

If you refer to connector of LCD flexible cable, a new LCD with same pinout and same mechanical of flexible cable is mandatory. I think it may difficult to find another LCD with same flexible cable of the LCD on MB1166 in the market. Another point is backlight of LCD should have same specification, otherwise MB1166 board can not be used for new LCD.

If you refer to the high speed connector between MB1166 and mother board, as I said, it is ST defined connector. If you want to replace MB1166 by a new LCD board, you need to develop a new LCD board and follow same pinout of the connector's definitions.

The display resolution of the LCD on MB1166 is 480x800, you can refer the features of MB1166 with it's User Manual: 4-inch WVGA TFT LCD board with MIPI® DSI interface and capacitive touch screen

The maximum resolution is based on the capability of MCU on mother board, for STM32H747,  it is limited by the available DSI physical link bandwidth:
Number of lanes: 2
Maximum speed per lane: 1 Gbps

You can find such information of datasheet of STM32H747,in page40:Datasheet - STM32H747xI/G - Dual 32-bit Arm®Cortex®-M7 up to 480MHz and -M4 MCUs, up to 2MB flash, 1MB RAM, 46 com. and analog interfaces, SMPS, DSI

Best Regards