Host MCU UART Communication Troubleshooting Flow

• UART Communication Checklist

1. Verify TX Output: Disconnect the physical connection between the Host MCU and the sensor. Using a logic analyzer, verify that the data write interface (as specified in Section 2.4 of the MRS2xx mmWare Radar Sensor Host Development Manual) outputs the expected data of LEN length at the correct baud rate.

2. After confirming the data in Step 1 is correct, connect the Host MCU TX pin to the sensor RX pin. Have the Host MCU continuously send 0x7E. Use a logic analyzer to monitor whether the sensor TX pin outputs 0x79.

3. Fully connect the Host MCU and the sensor (Host MCU RX pin to sensor TX pin). Use a logic analyzer to simultaneously monitor the system communication pins to verify if the Host MCU RX pin receives 0x79 after the Host MCU TX pin outputs 0x7E.

• Host MCU IIC Communication Troubleshooting Flow

1. Disconnect the Host MCU from the sensor. Use a logic analyzer to check whether the data read/write interface, adapted according to Section 2.4 of the MRS2xx mmWave Radar Sensor Host MCU Development Manual, causes the SDA and SCL lines to be pulled low when there is no device response.

2. After confirming Step 1 is correct, connect the Host MCU to the sensor. Use a logic analyzer to check if the data read/write interface, adapted according to Section 2.4 of the manual, correctly receives the device ACK.

3. Connect the Host MCU to the sensor. Have the Host MCU continuously send 0x7E. Use a logic analyzer to simultaneously monitor the system communication pins to verify if the Host MCU SDA pin reads 0x79 after the Host MCU SDA pin sends 0x7E.

• General Troubleshooting Flow

1. During system integration and restart, check whether the sensor is completely powered off (e.g., check for back-powering, such as the UART continuously providing a high logic level). Otherwise, the sensor will be in an abnormal power-on state, leading to unpredictable consequences.

2. Disconnect the Host MCU from the sensor. Manually pull the Host MCU DOUT pin high/low externally, and simultaneously check if the level read interface, adapted according to Section 2.4 of the MRS2xx mmWave Radar Sensor Host MCU Development Manual, returns the expected logic level.

3. Disconnect the Host MCU from the sensor. Confirm whether the radar DOUT pin can output the correct logic level when switching between target presence and absence states.