SEN0518 Sensor Reference: API, Protocol & Pinout

The article serves as a reference for understanding various libraries and communication protocols used in sensors, particularly focusing on heart rate, blood oxygen, and temperature data collection using Arduino and Raspberry Pi, along with CRC check algorithms and setup instructions.

Library

RTU Library (Modbus RTU protocol library for Arduino)
Heart Rate Sensor Library and Sample Codes Library (for Arduino, follow installation guide)
Heart Rate Sensor Python Library (for Raspberry Pi)

Communication Protocol Description

Note: The communication interface uses UART

Transmit	From Adevice to Bdevice
Functions	Bdevice Addess	Function Code	Register Address	Register Number	CRC Check
Get the Heart Rate and Blood Oxygen Data	0×20	0×03/Read	0×00 0×06	0×00 0×04	CRC_h CRC_l
Get the Temperature	0×20	0×03	0×00 0×0A	0×00 0×01	CRC_h CRC_l
Receive	Response from Bdevice
Functions	Bdevice Addess	Function Code	Valid Bytes	Data	CRC Check
Get the Heart Rate and Blood Oxygen Data	0×20	0×03	0×08	SPO2(1byte) xx(1byte reseved) Heartbeat(4byte) xx(2byte reserved)	CRC_h CRC_l
Get the Temperature	0×20	0×03	0×02	Temp_h Temp_l	CRC_h CRC_l

Set the Sensor	Transmit From Adevice
Functions	Bdevice Addess	Function Code	Register Address	Register Number	CRC Check
Start to Collet Data	0×20	0×06	0×00 0×10	0×00 0×01	CRC_h CRC_l
Stop Colleting Data	0×20	0×06	0×00 0×10	0×00 0×02	CRC_h CRC_l
Set the Sensor	Response From Bdevice
Functions	Bdevice Addess	Function Code	Valid Bytes	Data	CRC Check
Start to Collet Data	0×20	0×06	0×00 0×10	0×00 0×01	CRC_h CRC_l
Stop Colleting Data	0×20	0×06	0×00 0×10	0×00 0×02	CRC_h CRC_l

CRC check

static uint16_t calculate_CRC(uint8_t *data, uint8_t len)
{
  uint16_t crc = 0xFFFF;
  for( uint8_t pos = 0; pos < len; pos++)
  {
    crc ^= (uint16_t)data[ pos ];
    for(uint8_t i = 8; i != 0; i--)
    {
      if((crc & 0x0001) != 0){
        crc >>= 1;
        crc ^= 0xA001;
      }else{
        crc >>= 1;
      }
    }
  }
  crc = ((crc & 0x00FF) << 8) | ((crc & 0xFF00) >> 8);
  return crc;
}

API Description

/*!
 *  @brief Get heart rate and oxygen saturation and store them into the structure sHeartbeatSPO2
 *  @param NULL
 *  @return No value returned
 */
    void getHeartbeatSPO2();

/*!
 *  @brief Get the sensor board temp
 *  @param NULL
 *  @return Temp (unit: ℃)
 */
    float getTemperature_C();

/*!
 *  @brief Sensor starts to collect data
 *  @param NULL
 *  @return NULL
 */
    void sensorStartCollect();

/*!
 *  @brief Sensor stops collecting data
 *  @param NULL
 *  @return NULL
 */
    void sensorEndCollect();

Principle

The MAX30102 uses PPG(PhotoPlethysmoGraphy) to measure data, which will be converted into heart rate and oximetry values when processed by the MCU.

Other Supplementary Information

Wear Instructions

Wear

Use Guide for the Master Computer

Connect the sensor to the USB-to-serial port module.

Click to download the master computer of SEN0344 Heart Rate and Oximeter Sensor.

After decompressing, run SEN0344.exe, select the serial port and baud rate and click to start the measurement.