Thinkpads Forum

I recently discovered that the dock connector on the Thinkpad X1 tablet Gen 3 uses USB for the keyboard on the POGO pins, I want to use that connector to add a USB 2.0 hub to my tablet case (lenovo medical case for the X1 tablet)

Can't find much info on that bit online, but found lots of info for converting the Keyboards to USB. I wired up a USB port following https://sharktastica.co.uk/resources/im ... ogo-6p.jpg

If i connect a 10K resistor between ground/pin1 and pin5 (NC) i get a USB ding and then i see voltage on the 5V pin, but it drops to 2-3V when i plug in a flash drive and windows gives me a "USB device not recognized". but... if i supply external 5V to the flash drive, with the power disconnected from the tablet 5v pin, the tablet recognized and mounts the flash drive. there's gotta be a way to keep the USB pin voltage stable. unless it's going overcurrent trying to run a flash drive...

Dunno if anyone has done what i am trying to attempt before. Basically, need to somehow trick the tablet into thinking a keyboard is attached, so i can activate and use the USB port on the bottom of the tablet (6 pogo pins) without an external power supply on the USB port i'll be adding.

devicemodder wrote: ↑

Mon Jan 13, 2025 5:09 pm

snip
Dunno if anyone has done what i am trying to attempt before. Basically, need to somehow trick the tablet into thinking a keyboard is attached, so i can activate and use the USB port on the bottom of the tablet (6 pogo pins) without an external power supply on the USB port i'll be adding.

Don't know if you're still up on this, but it's been done https://spawn.link/posts/2019-02-18_-_l ... _keyboard/

I'm in the middle of doing this myself to a couple of clearance X1 tablet gen 3 keyboards I bought on pcsupport.lenovo.com for £13 each shipped.

I was looking for an off the shelf pogo to USB, but couldn't find one with 3mm pitch. Even if pinout was wrong I could easily fix that by cutting the cable and reconnecting it. I'd prefer the POGO-to-USB simplicity but it seems like a) the cable doesn't exist, b) 3mm pitch pogo ends aren't for sale on online marketplaces either.

I might eventually 3D print a connector and manually set pogo pins 3mm apart... then again I might just use a USB C breakout board, connect by soldering to pogo pins, then use a magnetic USB connector on the end of the cable to quickly connect/disconnect it as I switch out keyboards and peripherals often.

Good luck!

iamdmc wrote: ↑

Thu May 29, 2025 5:20 am

devicemodder wrote: ↑

Mon Jan 13, 2025 5:09 pm

snip
Dunno if anyone has done what i am trying to attempt before. Basically, need to somehow trick the tablet into thinking a keyboard is attached, so i can activate and use the USB port on the bottom of the tablet (6 pogo pins) without an external power supply on the USB port i'll be adding.

Don't know if you're still up on this, but it's been done https://spawn.link/posts/2019-02-18_-_l ... _keyboard/

I'm in the middle of doing this myself to a couple of clearance X1 tablet gen 3 keyboards I bought on pcsupport.lenovo.com for £13 each shipped.

I was looking for an off the shelf pogo to USB, but couldn't find one with 3mm pitch. Even if pinout was wrong I could easily fix that by cutting the cable and reconnecting it. I'd prefer the POGO-to-USB simplicity but it seems like a) the cable doesn't exist, b) 3mm pitch pogo ends aren't for sale on online marketplaces either.

I might eventually 3D print a connector and manually set pogo pins 3mm apart... then again I might just use a USB C breakout board, connect by soldering to pogo pins, then use a magnetic USB connector on the end of the cable to quickly connect/disconnect it as I switch out keyboards and peripherals often.

Good luck!

The link is for connecting the keyboard via usb instead of running other usb devices using the *pogo pins on the tablet*. As far as I have tried, simply using 4 wires to hook up a usb device on pins 2,3,4 & 6 doesn't work and it seems that the usb port only activates if the tablet detects a keyboard is attached (which I guess has to do with the NC pins). Did you have any success in attaching other usb devices to the tablet via the pogo connector?

liszejian wrote: ↑

Sun Jun 22, 2025 5:52 pm

iamdmc wrote: ↑

Thu May 29, 2025 5:20 am

Don't know if you're still up on this, but it's been done https://spawn.link/posts/2019-02-18_-_l ... _keyboard/

I'm in the middle of doing this myself to a couple of clearance X1 tablet gen 3 keyboards I bought on pcsupport.lenovo.com for £13 each shipped.

I was looking for an off the shelf pogo to USB, but couldn't find one with 3mm pitch. Even if pinout was wrong I could easily fix that by cutting the cable and reconnecting it. I'd prefer the POGO-to-USB simplicity but it seems like a) the cable doesn't exist, b) 3mm pitch pogo ends aren't for sale on online marketplaces either.

I might eventually 3D print a connector and manually set pogo pins 3mm apart... then again I might just use a USB C breakout board, connect by soldering to pogo pins, then use a magnetic USB connector on the end of the cable to quickly connect/disconnect it as I switch out keyboards and peripherals often.

Good luck!

The link is for connecting the keyboard via usb instead of running other usb devices using the *pogo pins on the tablet*. As far as I have tried, simply using 4 wires to hook up a usb device on pins 2,3,4 & 6 doesn't work and it seems that the usb port only activates if the tablet detects a keyboard is attached (which I guess has to do with the NC pins). Did you have any success in attaching other usb devices to the tablet via the pogo connector?

Yes someone told me to switch D- and D+ and now it works perfectly
wiring was incorrect in spawn link OP

Why couldn't you just plug a USB keyboard into one of the USB C ports via an adapter? Either that or just get a BT keyboard. I use a BT keyboard on my tablets from time to time. Works fine.