I am requesting a replacement for my PiCar-X Robot HAT due to a hardware failure on the I2C control circuit. The Raspberry Pi boots perfectly, and I can SSH into it without issue. The I2S audio speaker circuit on the HAT works fine, but the main microcontroller is completely unresponsive. I have fully verified the following in the terminal: 1. Ran `sudo pinctrl set 5 op dl` / `dh` to manually cycle the MCU reset line on GPIO 5, but the board remained frozen with red LEDs by the buttons. 2. Ran `sudo i2cdetect -y 1` (and scanned all other active buses), but the grid is completely blank. The main MCU address (14) is completely missing from the I2C bus. 3. Reseated the 40-pin header multiple times and completely disconnected all servos and sensors to rule out short circuits, but the I2C grid remains empty. Because the software environment is verified functional and the board fails to respond to physical resets or I2C polling, the HAT’s MCU appears to be dead. Please advise on how to secure a replacement board. Thank you!
Thank you for contacting us. We understand the issue you are experiencing with the Robot HAT on your PiCar-X, and we are here to help.
Before we proceed with further troubleshooting, please check a very important power issue: The Robot HAT requires its own independent power supply. It cannot operate solely from the Raspberry Pi’s power via the Type-C cable.
Please follow these steps:
Insert the battery into the Robot HAT and turn on the power switch on the Robot HAT. This is the most common cause—if the Robot HAT is not independently powered, its main MCU cannot function, and the I2C bus will not detect address 0x14. Please make sure the battery is correctly installed and fully charged, and the switch is set to the ON position.
Please take a photo showing:
The connection between the Robot HAT and the Raspberry Pi (including the ribbon cable)
Whether the battery is inserted into the Robot HAT
Whether the power switch is in the ON position
After confirming the power supply is normal, please run sudo i2cdetect -y 1 again to check if address 0x14 appears.
Please upload the photos to Google Drive (or another cloud drive) and share the link with us. Please make sure the link is set to “Anyone with the link can view” so we can access it.
Once we receive your photos, we will analyze further. If the power supply is confirmed to be normal but the MCU still cannot be detected, we will arrange a replacement for you. Thank you for your patience and cooperation!
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