# Power Supply

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# Power Supply Inlet and Adapter Requirements

- The Quectel Pi features a USB Type-C power interface, and the on-board power supply inlet is typically labeled as POWER IN.

- The product is powered via the POWER IN Type-C port.

- The power adapter is recommended to have an output capability of 5 V / 5 A or higher; the quick start documentation also emphasizes that the USB-A power cable (5A) included in the kit should be used, and power supplies with a current lower than 3A are prohibited.

- Insufficient power supply may cause frequent crashes of the intelligent main control board, abnormal startup or unstable operation of peripheral devices.

# Power-on and Startup Process

1. When connecting peripherals such as a monitor, keyboard and mouse, network cable, MIPI/HDMI, etc. , please disconnect the motherboard power supply first to avoid hot swapping.

2. Finally connect the power cable: plug the USB-A end into the power adapter, and plug the USB-C end into the POWER IN power port of the Quectel Pi.

3. After connecting to the power supply, you need to press and hold the PWRKEY button on the side of the board until the system starts up.

4. The power indicator is normally solid blue; the system indicator will normally stay on for a period of time before going out, indicating that the system is booting up; you can enter the desktop or access the system via the debug link after approximately 1 minute.

# Interface Power Supply and Prohibited Items

| **Interface/Scenario** | **Conclusions Related to Power Supply** | **Precautions** |
| --- | --- | --- |
| POWER IN Type-C | Mainboard power supply inlet, supporting USB PD 3.0; the adapter shall be capable of outputting at 5 V / 5 A or higher. | Preferentially use the cables included in the kit and adapters that meet the current rating requirements. |
| USB-C Debugging/Programming Interface | In the relevant safety instructions, this USB-C port is only used for firmware flashing and host mode communication, and shall not be used as the power input port of the motherboard. | Do not confuse the debug USB-C port with the POWER IN power supply port. |
| USB Device Mode | The device functions as a USB slave device, which is recognized and managed by the host computer; the Type-C port is used for ADB, firmware burning, and interaction with the host computer. | In this mode, USB peripherals such as external USB flash drives, keyboards and mice cannot be connected, and the device itself does not output USB power. |
| USB Host Mode | As a USB host, the device can actively control and manage connected external USB devices and supply USB power to these peripherals. | Only suitable for ordinary USB peripherals; do not draw power for high-power modules from the motherboard's USB/GPIO pins. |
| GPIO/40-pin Expansion | It supports expansion for functions including GPIO, I2C, SPI, UART, PWM, etc. | Do not draw power for high-power modules through the GPIO port; when testing pin voltage, make sure the GND connection is correct. |
| ADC Input | For ADC0/ADC1 testing, an adjustable DC power supply can be used as the input signal source, and the GND of the power supply must be connected to the GND of the motherboard for common grounding. | ADC0/ADC1 supports an input voltage range of approximately 0~5.25 V, and over-range input shall be avoided. |
| MIPI/HDMI Display | The display screen needs to confirm that its power supply is stable. For MIPI screens, connect the power supply in accordance with the hardware instructions, while HDMI displays require separate power-on. | It is recommended to turn off the power supply of the motherboard before connecting or disconnecting the display cable/wire harness. |

# Peripheral Power Supply Principles

- External high-power modules (such as motors) must be powered separately, and power must not be drawn from the USB port or GPIO port of the main control board to avoid board burnout caused by overload.

- Before connecting peripherals such as camera flexible flat cables, network cables, MIPI cables and HDMI cables, the power supply of the motherboard shall be disconnected first; hot plugging may damage the interface chip or cause abnormalities in the display or camera.

- If the MIPI screen requires independent power supply, ensure that the power supply interface is connected stably; when encountering issues such as black screen on power-on, distorted display, or unresponsive touch, prioritize checking the cable orientation, latch status, and screen power supply.

- If an HDMI display abnormality occurs, first check the monitor's power supply, input source selection, Micro HDMI cable connection, and system startup status.

- During the acceptance test of peripherals such as GNSS, it is also necessary to confirm that the power supply of the development board is stable, so as to avoid misjudging power supply fluctuations as functional problems.

# Electrical and Commissioning Precautions

- Specification Notice: Exceeding the absolute maximum rating conditions may cause permanent damage.

- The 2 × 20-pin I/O interface must be used in accordance with the digital logic level specifications specified in the document, and direct connection of external high voltage to regular GPIOs shall be avoided.

- The Debug UART debug board shall support 3.3 V level, and be correctly cross-connected as GND, TXD, RXD; incorrect connection may result in communication failure or hardware damage.

- During ADC testing, connect the positive terminal of the adjustable DC power supply to ADC0/ADC1; the pin input range is approximately 0 to 5.25 V, and the GND of the power supply must be connected to the GND of the motherboard.

- It is recommended to take proper ESD protection measures during R&D, production, assembly and testing, such as wearing anti-static gloves and adding protection components at positions vulnerable to static electricity like interfaces.

# Troubleshooting Directions for Common Issues

| **Phenomenon** | **prioritize troubleshooting** | **Description** |
| --- | --- | --- |
| Frequent crashes / abnormal startup | Adapter current capacity, wire specifications, and whether a power supply below 3A is used | Priority should be given to replacing with an adapter and kit cables rated at 5 V / 5 A or above. |
| Display not turning on / distorted screen | Screen power supply, cable orientation, FPC lock, and display interface are available in optional dual configurations | It is not recommended to use MIPI and Micro HDMI as dual-screen output at the same time; it is recommended to power on again after switching the display interface. |
| USB peripheral device not recognized | whether the DIP switch is in Host mode, whether the Type-C port outputs power, and whether the peripheral power consumption is excessive | Device mode is mainly used for ADB/burning, not for ordinary USB peripheral expansion. |
| Camera failed to load | cable connection, I2C address, power-on sequence, cam-server service and dmesg probe log | The FAQ indicates that when no probe information is available, the I2C address or power-on sequence of the sensor should be checked. |
| Abnormal ADC Reading | Input voltage range, whether GND shares a common ground, and whether the node path is correct | The input voltage range of ADC0/ADC1 is approximately 0 to 5.25 V, and the reading unit is μV. |