Pogo pins power clarification - reading schematics
03-01-2021, 12:24 AM
Hi All, just wanting to relate my experience on this fascinating but rather complex topic, in the hopes of finding a solution for my needs.
A bit of background - I am wanting to use the PinePhone as a miniaturised version of the Pine A64 LTS SBC with the screen built-in. I have a prototype that looks quite a lot like Project Anakin floating around :-)
There is an RS232 USB device (a sensor) which I connect to the PinePhone USB-C with a USB-A adapter. I'd like to be able to charge the phone via the pogo pins (DCIN/GND) while also powering and reading from the USB sensor. I could do this on the A64 LTS no issue (via DCIN barrel). Mobian is the operating system on the PinePhone, Armbian on the A64 LTS.
On the PinePhone:
* Before attaching the USB device, I found that I could charge via DCIN. Good.
* I then attached the USB device without supplying power to DCIN. USB device worked fine. Good.
* I then supplied +5V to DCIN. Good new? No magic smoke! Bad news? No charging.
* For completeness, I disconnected the USB device and supplied power to DCIN - charging OK.
* While charging I connected the USB device - device would not come up (/dev/ttyUSB*). I have to disconnect the power to DCIN to get the USB device to register.
Another side effect is that the device will not stay off with DCIN powered - no charging while switched off, it keeps booting up again :-(
I'd love if there was a magic way to charge the phone via a pogo pin (ie USB-5V) as debated here, perhaps with USB driver / kernel trickery. My fall-back position right now is to wait for the keyboard/battery to come out and borrow their strategy, assuming they can charge the phone and host a USB device at the same time. Fingers crossed!
Questions:
* Has anyone tried this on KDE/Manjaro or other distro with better results?
* Any chances some USB driver / kernel trickery could fix my problems?
Other comments:
* The wiki should really be updated! At very least I suggest a link to this discussion, mostly to help people avoid possibly costly mistakes.
* On the A64 LTS (same AXP803 PMIC), the USB +5V rail gets battery voltage when the board is powered down - which sucked, I had to devise a high-side MOSFET switch to work around it. High-side because the screen I was using provided a ground route to all USB devices...ugh
A bit of background - I am wanting to use the PinePhone as a miniaturised version of the Pine A64 LTS SBC with the screen built-in. I have a prototype that looks quite a lot like Project Anakin floating around :-)
There is an RS232 USB device (a sensor) which I connect to the PinePhone USB-C with a USB-A adapter. I'd like to be able to charge the phone via the pogo pins (DCIN/GND) while also powering and reading from the USB sensor. I could do this on the A64 LTS no issue (via DCIN barrel). Mobian is the operating system on the PinePhone, Armbian on the A64 LTS.
On the PinePhone:
* Before attaching the USB device, I found that I could charge via DCIN. Good.
* I then attached the USB device without supplying power to DCIN. USB device worked fine. Good.
* I then supplied +5V to DCIN. Good new? No magic smoke! Bad news? No charging.
* For completeness, I disconnected the USB device and supplied power to DCIN - charging OK.
* While charging I connected the USB device - device would not come up (/dev/ttyUSB*). I have to disconnect the power to DCIN to get the USB device to register.
Another side effect is that the device will not stay off with DCIN powered - no charging while switched off, it keeps booting up again :-(
I'd love if there was a magic way to charge the phone via a pogo pin (ie USB-5V) as debated here, perhaps with USB driver / kernel trickery. My fall-back position right now is to wait for the keyboard/battery to come out and borrow their strategy, assuming they can charge the phone and host a USB device at the same time. Fingers crossed!
Questions:
* Has anyone tried this on KDE/Manjaro or other distro with better results?
* Any chances some USB driver / kernel trickery could fix my problems?
Other comments:
* The wiki should really be updated! At very least I suggest a link to this discussion, mostly to help people avoid possibly costly mistakes.
* On the A64 LTS (same AXP803 PMIC), the USB +5V rail gets battery voltage when the board is powered down - which sucked, I had to devise a high-side MOSFET switch to work around it. High-side because the screen I was using provided a ground route to all USB devices...ugh
