Power supply¶
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Power Input and Adapter Requirements¶
The main power input of the Quectel Pi is a USB Type-C port, usually labeled POWER on the board.
It is recommended to use the USB-C power cable (5A) included with the kit and an adapter that meets the output requirements. The documentation requires an adapter capable of delivering at least 5 V / 5 A. An adapter supporting USB PD can negotiate power delivery according to the board specifications.
Insufficient power may result in power-on failure, frequent system freezes, abnormal system startup, disconnection of USB peripherals, and unstable operation of peripherals such as Wi-Fi and Bluetooth. If these issues occur, first rule out problems with the adapter, power cable, and connectors.
Before connecting a camera, display, USB peripheral, or other module, disconnect power from the mainboard. Hot-plugging may damage interface components and may also cause transient power supply abnormalities.
Power-On and Startup Procedure¶
When connecting peripherals such as a monitor, keyboard and mouse, Ethernet cable, camera, MIPI, or HDMI device, first disconnect power from the mainboard and confirm that the interface orientation, latches, and plugs are correct.
Connect the power cable last: connect the USB-A end to the adapter and the USB-C end to the POWER IN port on the Quectel Pi. Do not use the Type-A debugging/flashing port as the mainboard power input.
After power is connected, the development board powers on automatically and the system begins to boot. The power indicator is usually solid blue, while the system indicator usually lights up and then turns off. After about half a minute, you can access the desktop or access the system through ADB/serial port/SSH.
If starting in USB Device/ADB mode, ensure that the data cable connected to the computer is plugged into the corresponding USB Device/debugging port. This connection is used for communication with the host computer and is not equivalent to POWER supply.
Interface Power Supply and Prohibited Practices¶
Interface/Scenario |
Power Supply Information |
Precautions |
|---|---|---|
POWER IN Type-C |
Mainboard power input supporting USB PD 3.0; the adapter must be capable of delivering at least 5 V / 5 A. |
Preferably use the cable included with the kit and an adapter with sufficient current capacity. |
USB-A debugging/flashing port |
According to the relevant safety instructions, this USB-A port is intended only for firmware flashing and host-mode communication and must not be used as the mainboard power input. |
Do not confuse the debugging USB-A port with the POWER IN port. |
USB Device mode |
The device operates as a USB peripheral and is recognized and controlled by the host computer; the Type-C side is used for ADB, firmware flashing, and host-computer interaction. |
In this mode, USB peripherals such as USB flash drives, keyboards, and mice cannot be connected, and the device itself does not supply USB power. |
USB Host mode |
The device operates as a USB host, can actively control connected USB devices, and supplies USB power to the peripherals. |
This is suitable only for ordinary USB peripherals; do not power high-power modules from the mainboard’s USB/GPIO ports. |
GPIO/40-pin expansion |
Supports expansion via GPIO, I2C, SPI, UART, PWM, and other interfaces. |
Do not power high-power modules through the GPIO port. When measuring pin voltage, ensure that GND is connected correctly. |
MIPI/HDMI display |
Ensure that the display has a stable power supply. Connect power to a MIPI display according to the hardware instructions; an HDMI monitor must be powered separately. |
It is recommended to turn off mainboard power before connecting or removing a display flex cable/cable. |
Peripheral Power Supply Principles¶
External high-power modules (such as motors) must be powered separately and must not draw power through the main control board’s USB or GPIO port, to avoid overloading and damaging the board.
Before connecting peripherals such as camera flex cables, Ethernet cables, MIPI flex cables, and HDMI cables, disconnect power from the mainboard. Hot-plugging may damage interface chips or cause display/camera abnormalities.
If a MIPI display requires an independent power supply, ensure that its power connector is securely connected. If the screen is black or garbled at startup or touch does not respond, first check the flex cable orientation, latch status, and display power supply.
If the HDMI display is abnormal, first check the monitor’s power supply, input source selection, Micro HDMI cable connection, and system startup status.
When performing acceptance testing on peripherals such as GNSS, also ensure that the development board has a stable power supply to avoid mistaking power fluctuations for functional issues.
Electrical and Debugging Precautions¶
The specifications warn that exceeding the absolute maximum ratings may cause permanent damage.
The 2 × 20-pin I/O must be used according to the digital logic level characteristics in the documentation. Avoid directly connecting an external high voltage to an ordinary GPIO.
The Debug UART adapter board must support 3.3 V levels and be cross-connected correctly according to GND, TXD, and RXD. Incorrect connections may prevent communication or damage the hardware.
ESD protection is recommended during R&D, production, assembly, and testing, such as wearing anti-static gloves and adding protective components at interfaces and other locations susceptible to static electricity.
Common Troubleshooting Directions¶
Symptom |
Check First |
Description |
|---|---|---|
Frequent system freezes/abnormal startup |
Adapter current capacity, cable specifications, and whether a power supply below 3A is being used |
Preferably replace them with an adapter rated at 5 V / 5 A or higher and the cable included with the kit. |
Display does not light up/garbled display |
Display power supply, flex cable orientation, FPC latch, and selection of one of the two display interfaces |
Using MIPI and Micro HDMI simultaneously for dual-display output is not recommended. It is recommended to power-cycle the board after switching the display interface. |
USB peripheral cannot be recognized |
Whether Type-C is supplying power and whether the peripheral’s power consumption is excessive |
Device mode is primarily used for ADB/flashing, not for ordinary USB peripheral expansion. |
Camera cannot be loaded |
Flex cable connection, I2C address, power-on sequence, cam-server service, and dmesg probe logs |
The FAQ states that if there is no probe information, the sensor’s I2C address or power-on sequence should be checked. |