Is it possible to connect an amd framework mainboard to this third party EDP touch display using a 40 to 30 pin edp cable?
Handhelds are all the rage and would love If I could use something like this so that I could save power and control the display from the OS
Are there pinouts? Took a quick look and I didn’t see any. Personally, I wouldn’t try it with anything that didn’t provide their pinout. I understand there are some semi-standard pinouts, but I just wouldn’t want to risk an expensive mainboard.
Framework display side connector pinout: https://github.com/FrameworkComputer/Framework-Laptop-13/tree/main/Display#pinout
For touchscreen, you’d need a display that uses usb for the touch signals, and it would be easiest if it was on a second cable. I see a second cable on the screen you linked, so that’s good. With usb touch on a second cable, you could connect that to any free usb port.
~edit~
Oh, I somehow missed that with the cable you linked, you’re suggesting connecting that cable straight to the Framework mainboard. No, that won’t work. The mainboard side pinout isn’t one of the semi-standard pinouts. You must use Framework’s cable.
Good to know eDP pin outs are not always consistant. On that display there’s an FPC for eDP and touch but yeah, maybe the cap touch FPC is just carrying usb signals. Thanks for those resources @MJ1. This will help in my search.
~edit~
Actually, Is I2C. There’s a pinout in the latte panda docs
I don’t know how eDP works, but if I used an intermediary fpc adaptor, and only hooked up the 2 lanes from the display to 2 out of the 4 on the framework mainboard (and passed through all the other signals) - would that work? I guess you’d be out of luck with regards to the i2c touch interface anyway
| Pin | Signal | Notes | EQUIV_LP_DISPLAY_SIGNAL? | EQUIV_LP_DISPLAY_PIN |
|---|---|---|---|---|
| 1 | NC | CSI_USB | 30 | |
| 2 | GND | Signal ground | NC | |
| 3 | EDP_TXN_3 | NC | ||
| 4 | EDP_TXP_3 | NC | ||
| 5 | GND | Signal ground | GNC | 1 |
| 6 | EDP_TXN_2 | NC | ||
| 7 | EDP_TXP_2 | NC | ||
| 8 | GND | Signal ground | GND | 2 |
| 9 | EDP_TXN_1 | TX1_DN | 3 | |
| 10 | EDP_TXP_1 | TX1_DP | 4 | |
| 11 | GND | Signal ground | GND | 5 |
| 12 | EDP_TXN_0 | TX0_DN | 6 | |
| 13 | EDP_TXP_0 | TX0_DP | 7 | |
| 14 | GND | Signal ground | GND | 8 |
| 15 | AUXP | AUX_DP | 9 | |
| 16 | AUXN | AUX_DN | 10 | |
| 17 | GND | Signal ground | GND | 11 |
| 18 | 3V_EDP | 3.3V typical | 3.3V | 12 |
| 19 | 3V_EDP | 3.3V typical | 3.3V | 13 |
| 20 | 3V_EDP | 3.3V typical | NC | |
| 21 | 3V_EDP | 3.3V typical | NC | |
| 22 | SELF_TEST | Self test enable | LCD_RST | 14 |
| 23 | GND | Digital ground | GND | 15 |
| 24 | GND | Digital ground | GND | 16 |
| 25 | GND | Digital ground | NC | |
| 26 | GND | Digital ground | NC | |
| 27 | EDP_HPD | Hot plug detect output | EDP_HPD | 17 |
| 28 | GND | Backlight ground | BL_GND | 18 |
| 29 | GND | Backlight ground | BL_GND | 19 |
| 30 | GND | Backlight ground | BL_GND | 20 |
| 31 | GND | Backlight ground | BL_GND | 21 |
| 32 | BLK_OFF_N | 3.3V input | BL_EN | 22 |
| 33 | BLK_PWM_LCD | 200Hz to 2kHz, 3.3V | BL_PWM | 23 |
| 34 | NC | CSI_USB_DP | 24 | |
| 35 | NC | CSI_USB_DN | 25 | |
| 36 | BL_POWER | 5V-21V | BL_PWR | 27 |
| 37 | BL_POWER | 5V-21V | BL_PWR | 28 |
| 38 | BL_POWER | 5V-21V | BL_PWR | 29 |
| 39 | BL_POWER | 5V-21V | NC | |
| 40 | NC | NC | 26 |
I was thinking about that. I see that there are “adapters” that claim to be 30 pin to 40 pin eDP. And I see that the difference between the common 30 pin vs 40 pin is just dropping 2 lanes and a couple less of the duplicated VCC and GND pins. So pinout wise, there is some potential for those adapters. Wouldn’t just trust them though, need to confirm with a multimeter.
Beyond the pinout, I don’t know enough about how eDP is usually implemented to know if it’s likely to seamlessly accept only 2 lanes. I read some say that it’s supposed to. Though “supposed to” and usually does in practice are two different things.
See this thread for more talk about potentially using different displays: Different battery and display (smaller)? Note that Arya in that thread is the one who wrote the link on Common eDP pinouts (part of the All About Laptop Display Reuse info resource).
While it might not help for that particular display, it could be of help for others, if 2-lane 30pin to 4-lane 40pin eDP can work. A lot of smaller displays seems to use 30 pin, since they’re normally low enough resolution that they only need 2 lanes and so 30 pin is adequate.
Rather than the display signals I suppose I should have compared the mainboard eDP interface to the latte panda interface. This has usb and i2c signals. Perhaps it’s possible to route the display’s touch and video signals onto the 40pin cable and onto the framework mainboard.
Yeah, the problem with the mainboard display connector is that it’s a custom pinout, I read that laptops just don’t follow any standard, or even semi-standard, for their motherboard display connectors. So you need a custom cable to connect to it. And I understand custom display cables are quite expensive to have made, prohibitively expensive for individuals. Also, there is no mating PCB-mounted connector available. So you must use a custom cable. A PCB adapter is not possible.
Even if you could, you’d need to find out if i2c touchscreens follow a standard and automatically work. I2c isn’t like usb. I2c at its base is very much is not expected to just work. I2c devices set their own rules for how you have to talk to them.
