Xbee3 Micropython and TE MS8607 PHT Sensor

ScottRaeker · March 5, 2021, 9:05pm

Introduction

This details an example of interfacing TE Connectivity’s MS8607 PHT combination sensor to Digi International’s XBee3 intelligent wireless module (programmed with 802.15.4 protocol firmware). The project uses the MS8607 sensor included on TE’s weather shield connected over I2C to Digi International’s Grove development board with an Xbee 3 wireless module plugged in. A Micropython script running on the Xbee3 communicates with the MS8607 sensor to read the I2C address and trigger/measure barometric pressure, humidity and temperature.

Hardware Requirements

XB3-24Z8US-J Digi XBee3 RF Module at Digi-Key (note: module was re-programmed with 802.15.4 firmware)
XBee SMT Grove Development Board at Digi-Key
TE Connectivity Arduino Weather Shield at Digi-Key

Supplier Documentation

Digi International Digi XBee3® 802.15.4 User Guide
Digi International Digi MicroPython Programming Guide
Digi International Xbee Grove Development Board User Guide
TE Connectivity Arduino Weather Shield Datasheet
TE Connectivity MS8607 PHT Combination Sensor Data Sheet

Hardware Setup

TE Weather Shield

TE Connectivity’s Weather Shield is an Arduino form factor sensor evaluation board with five TE environmental sensors mounted. The five sensors are the HTU21D Humidity/Temperature Sensor, MS5637 Pressure Sensor, MS8607 Pressure Sensor, TSYS01 Temperature Sensor, and TSD305-1C55 Contactless Temperature Sensor. All five sensors communicate on the I2C bus which is routed through a CD74HC4502 mux/demux IC to provide switching of the I2C bus to the various sensors. For selection of the MS8607 sensor the input CA is set to Vdd and CB and EN need to be set “low”.

Xbee SMT Grove Board

Digi International’s Xbee SMT Grove board is a development platform allowing use of multiple SMT form factor Xbee wireless modules. Various Xbee signals, including I2C, are routed to eight grove connectors on the board to allow easy interface to external devices.

Example Code

github.com

eewiki/Xbee3-MicroPython/blob/master/samples/TE_MS8607_i2c.py

# Micropython code example for Digi International Xbee3
# 802.15.4 module interface to TE Weather Shield MS8607
# digital barometric pressure and humidity sensor over I2C
#  


from micropython import const
import utime
import ustruct
import machine

# list of commands in hex for MS8607 pressure sensor
c_reset = const(0x1E) # reset command 
r_c1 = const(0xA2) # read PROM C1 command
r_c2 = const(0xA4) # read PROM C2 command
r_c3 = const(0xA6) # read PROM C3 command
r_c4 = const(0xA8) # read PROM C4 command
r_c5 = const(0xAA) # read PROM C5 command
r_c6 = const(0xAC) # read PROM C6 command
r_adc = const(0x00) # read ADC command

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Description

MicroPython code that runs on a Xbee 3 wireless module connected to an MS8607 pressure sensor over I2C. The example code scans the I2C bus and prints active addresses, resets the sensor, reads calibration data stored in onboard PROM and reads/converts barometric pressure, temperature and humidity in a continuous loop.

TE Connectivity MS8607 Sensor Calculation Background

Configuration settings and calculations used are based on MS8607-02BA01 datasheet per below: