Table of Contents
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Measuring Heart Rate and SpO
2
Using the MAX32664A – A Quick Start Guide
UG7087; Rev 0; 8/19
Abstract
The MAX32664A is a variant of the MAX32664 sensor-hub family, which is specifically targeted
for the finger-based measurement of heart rate and SpO
. Combined with the MAX30101 optical
2
sensor and a 3-axis accelerometer, it provides a sensor's raw data, as well as calculated heart-
rate and SpO
data to a host device through its I
2
C slave interface. This document provides
2
step-by-step instructions that enable a user to communicate with the MAX32664A, and to
calibrate, configure, and receive measurement and monitoring data.
Maxim Integrated
Page 1 of 15
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Summary of Contents for Maxim Integrated MAX32664A
- Page 1 Using the MAX32664A – A Quick Start Guide UG7087; Rev 0; 8/19 Abstract The MAX32664A is a variant of the MAX32664 sensor-hub family, which is specifically targeted for the finger-based measurement of heart rate and SpO . Combined with the MAX30101 optical sensor and a 3-axis accelerometer, it provides a sensor’s raw data, as well as calculated heart-...
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Page 2: Table Of Contents
Figure 1. Architecture diagram for health-sensing applications..........4 List of Tables Table 1. Read Status Byte Value ....................5 Table 2. Host-Side Accelerometer—Sending Data to the MAX32664A ........6 Table 3. Configurations and Settings—HR/SpO ................ 8 Table 4. Host Commands—SpO Calibration ................ -
Page 3: Introduction
Introduction The MAX32664A is a variant of the MAX32664 sensor-hub family that enables users to capture raw data as well as calculated heart-rate and SpO data through finger contact. The MAX32664A is preprogrammed with the firmware, drivers, and algorithm that are required to interface with the MAX30101 sensor device through an I C master port. -
Page 4: Architecture
Application or Bootloader mode through the RSTN and multifunction input/output (MFIO) pins. An MFIO pin is also used in Application mode to interrupt the host for I C communication. The MAX32664A interfaces with the MAX30101 optical sensor through a second I C bus. To enter Bootloader mode: •... -
Page 5: Communicating With The Max32664A
1.1 Communicating with the MAX32664A A host should use the I C bus to communicate with the MAX32664A (slave) using a series of commands. A generic write command includes the following fields: Slave_WriteAddress(1 byte)|Command_Family(1 byte)|Command_Index(1 byte)|Value(multiple bytes) A generic response includes the following fields: Slave_ReadAddress(1 byte)|Status(1 byte)|Value(multiple bytes) Slave_WriteAddress and Slave_ReadAddress are set to 0xAA and 0xAB, respectively. -
Page 6: Accelerometer
1.2 Accelerometer For best results, it is recommended that accelerometer data be provided to the MAX32664A. calculation requires a resting condition, and the algorithm uses accelerometer data to detect excessive motion. In such a condition, computation is paused, and the user is informed with a motion flag. -
Page 7: Calibration Of The Spo 2 Algorithm
Using the Maxim MAX32664 Sensor Hub application note. Once three calibration coefficients are obtained, they need to be loaded to the MAX32664A every time prior to starting the algorithm. But first, they are required to be converted to a 32-bit integer... -
Page 8: Algorithm Settings And Configurations
INDEX INDEX VALUE calibration coefficients* A = 1.5958422 0x50 for 100,000 (12 bytes comprised of (0x00026f60) write three 32-bit signed values) B = -34.659664 0x02 0x0B (0xffcb1d12) 0x51 for C = 112.68987 read (0x00abf37b) Maxim Integrated Page 8 of 15... -
Page 9: Table 4. Host Commands-Spo 2 Calibration
Wait for 100ms before sending the next command. Any command to change sensor registers should appear AFTER enabling the algorithm or they will be overwritten. Host reads the samples upon receiving the MFIO interrupt from the MAX32664A. For SpO calibration, continue as needed to capture the R value. See Table 5. -
Page 10: Table 5. Format Of Received Samples-Spo
-2: Device excessive motion status -3: No object -4: Pressing too hard -5: Object instead of finger -6: Finger excessive motion Reserved Reserved *If the output mode includes the sensor. **If the output mode includes the algorithm. Maxim Integrated Page 10 of 15... -
Page 11: Measuring Heart Rate And Spo 2 On Finger
Finger 3.1 Raw Data Collection Mode For hardware testing purposes, the user may choose to start the MAX32664A to collect raw PPG samples. In this case, the host configures the MAX32664A to work in Raw Data mode (no algorithm report). Table 6 lists the set of commands that are needed to work in this mode. In Raw Data mode, only raw PPG samples and accelerometer data are included in the received samples. -
Page 12: Table 7. Format Of Received Samples-Raw Data Mode
Red counter MAX30101 (12 Bytes)* LED3 LED4 Two's complement. LSB = accelX 0.001g Accelerometer Two's complement. LSB = accelY (6 Bytes)* 0.001g Two's complement. LSB = accelZ 0.001g *If the output mode includes the sensor. Maxim Integrated Page 12 of 15... -
Page 13: Algorithm Mode: Heart Rate And Spo 2
The format of the AB 00 algorithm report) samples is shown in Table 9. Host reads the samples upon receiving the MFIO interrupt by the MAX32664A. AA 00 00 Read the sensor hub status byte: AB 00 08 Bit 0: Sensor comm error... -
Page 14: Table 9. Format Of Received Samples-Hr/Spo
0: No object is detected Algorithm 1: Something is on sensor state 2: Another object is detected 3: Finger is detected *If the output mode includes the sensor. **If the output mode includes the algorithm. Maxim Integrated Page 14 of 15... -
Page 15: Revision History
Initial release — ©2019 by Maxim Integrated Products, Inc. All rights reserved. Information in this publication concerning the devices, applications, or technology described is intended to suggest possible uses and may be superseded. MAXIM INTEGRATED PRODUCTS, INC. DOES NOT ASSUME LIABILITY FOR OR PROVIDE A REPRESENTATION OF ACCURACY OF THE INFORMATION, DEVICES, OR TECHNOLOGY DESCRIBED IN THIS DOCUMENT.
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