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Prime does not turn on after charging
08-14-2019, 01:22 PM
Post: #13
RE: Prime does not turn on after charging
(08-13-2019 03:56 PM)olr Wrote:  It's a revision A (NW280AA). I'm not experienced with attaching to UART TX. Any hints, where i can find it on the board? I would need to find the hardware and time (and motivation) to start this experiment.

On a revision A, the UART_RX and UART_TX pads (labeled as such) should be located near the bottom-right of the SoC chip, the one with red goo corners. To interface with it you need a 3.3v TTL UART, which is commonly done with a USB TTL serial cable, costs about €10. Plug the USB serial cable in, open a terminal emulator to it, connect the ground wire to the USB plug shield, the RX wire to the UART_TX pad (no need to solder for a quick check) and reset the calculator. A bootlog should appear on the terminal emulator.

If you're not sure about your setup, short the RX and TX wires of the USB serial cable together and type stuff on your keyboard. The characters should echo back on the terminal emulator.

(08-13-2019 11:11 AM)toml_12953 Wrote:  Have they removed the UART pad from the G2?

It's still there, but it's located on the back of the motherboard now, along with a bazillion pads including JTAG. The official firmware doesn't output anything at all over the UART, but I assume the U-Boot/Linux port done by Zephray Wenting can use it (haven't tried it yet).
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Messages In This Thread
Try a different cable - striegel - 08-11-2019, 02:02 PM
RE: Prime does not turn on after charging - Jean-Baptiste Boric - 08-14-2019 01:22 PM

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