# GameShell UART for Debug

**URL:** https://forum.clockworkpi.com/t/gameshell-uart-for-debug/1526
**Category:** GameShell
**Tags:** tinkering, hardware, serial
**Created:** [August 30, 2018, 10:28am UTC](https://forum.clockworkpi.com/t/gameshell-uart-for-debug/1526 "2018-08-30T10:28:35Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![steward-fu](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/steward-fu/32/1076_2.png) [@steward-fu](https://forum.clockworkpi.com/u/steward-fu)
#### Post date: [August 30, 2018, 10:28am UTC](https://forum.clockworkpi.com/t/gameshell-uart-for-debug/1526/1 "2018-08-30T10:28:35Z")

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Hi,  
If you prefer debug via UART, you might try to find out it from main board.  
But since the label of J46 on mainbaord is incorrect, so, nothing will be printed when boot up.  
After investigated, finally, the label is inverted.  
For more detailed information, please refer to the following:  
[https://steward-fu.github.io/website/handheld/gameshell/uart.htm](https://steward-fu.github.io/website/handheld/gameshell/uart.htm)

Pin you need for UART debug:  
GND  
UART TX =\> PB0 (UART0\_TX)  
UART RX =\> PB1 (UART0\_RX)

schematic from clockworkpi github:  
 ![](https://cdck-file-uploads-canada1.s3.dualstack.ca-central-1.amazonaws.com/flex029/uploads/clockworkpi/original/2X/b/b5142e1666ab1883717b4c71636203b5b6422b9b.jpeg)

UART debug port located on J46  
 ![](https://cdck-file-uploads-canada1.s3.dualstack.ca-central-1.amazonaws.com/flex029/uploads/clockworkpi/original/2X/9/9cbca883b8a9edf992b30666b6a84b43bf96031e.jpeg)

J46 on mainboard  
 ![](https://cdck-file-uploads-canada1.s3.dualstack.ca-central-1.amazonaws.com/flex029/uploads/clockworkpi/original/2X/9/906764b6ef4dc054f4c1d3f6431dfe73bc86a7e3.jpeg)

3.3V USB to UART  
 ![](https://cdck-file-uploads-canada1.s3.dualstack.ca-central-1.amazonaws.com/flex029/uploads/clockworkpi/original/2X/b/ba7a0e99f16407cc7b8f5412ce3819ee04f0b299.jpeg)

connect it but nothing happen when booting  
 ![](https://cdck-file-uploads-canada1.s3.dualstack.ca-central-1.amazonaws.com/flex029/uploads/clockworkpi/original/2X/f/fe2874dca3381a4382aa20b6052fd993c7b90f99.jpeg)

GND pin  
[https://steward-fu.github.io/website/handheld/gameshell/uart/6.jpg](https://steward-fu.github.io/website/handheld/gameshell/uart/6.jpg)

invert direction (pin1 =\> schematic p14, pin14 =\> schematic p1)  
 ![](https://cdck-file-uploads-canada1.s3.dualstack.ca-central-1.amazonaws.com/flex029/uploads/clockworkpi/original/2X/7/7914229ecd8693461ce850d50609ad76f983ab81.jpeg)

U-Boot SPL 2018.01-rc1-00116-g214ced3654 (Jun 08 2018 - 16:32:06)  
DRAM: 512 MiB  
Trying to boot from MMC1

U-Boot 2018.01-rc1-00116-g214ced3654 (Jun 08 2018 - 16:32:06 +0800) Allwinner Technology

CPU: Allwinner A33 (SUN8I 1667)  
Model: clockworkpi CPI3  
DRAM: 512 MiB  
MMC: SUNXI SD/MMC: 0, SUNXI SD/MMC: 1  
Card did not respond to voltage select!  
mmc\_init: -95, time 22  
\*\*\* Warning - MMC init failed, using default environment

Setting up a 320x240 lcd console (overscan 0x0)

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<div class="post-metadata">

### Author: ![Godzil](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/godzil/32/60_2.png) [@Godzil](https://forum.clockworkpi.com/u/Godzil)
#### Post date: [August 30, 2018, 10:35am UTC](https://forum.clockworkpi.com/t/gameshell-uart-for-debug/1526/2 "2018-08-30T10:35:45Z")

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Hi, @steward-fu sorry for the forum being itself 😉

I’m pushing you to the level where you can put more images, feel free to edit your post to update it, and thanks for your contribution, it is very welcome! (they are anti-spam feature to try to prevent bots to flood the forum)

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<div class="post-metadata">

### Author: ![steward-fu](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/steward-fu/32/1076_2.png) [@steward-fu](https://forum.clockworkpi.com/u/steward-fu)
#### Post date: [August 30, 2018, 11:01am UTC](https://forum.clockworkpi.com/t/gameshell-uart-for-debug/1526/3 "2018-08-30T11:01:48Z")

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thanks 🙂

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<div class="post-metadata">

### Author: ![guu](https://avatars.discourse-cdn.com/v4/letter/g/7ab992/32.png) [@guu](https://forum.clockworkpi.com/u/guu)
#### Post date: [August 30, 2018, 11:42am UTC](https://forum.clockworkpi.com/t/gameshell-uart-for-debug/1526/4 "2018-08-30T11:42:08Z")

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awesome  
It’s useful

thanks