ESP32-GPS-msec-ts.ino

msec IoT time stamper by ESP32 using GPS (GY-NEO6MV2 board)

• for Arduino IDE (FreeRTOS feature is used to demonstrate sensor access as a Task)
• 1PPS(TIMEPULSE) signal from NEO6M is connected GPIO_NUM_26 to interrupt ESP32 and deciplines ESP32's time stamp for MQTT publication.
• TinyGPS++ is used to decode NMEA sentenses.
• MQTT publication code is not included, just print out JSON format data for thingsboard , providing time stamp in msec.

serial output (115200bps)
ex. UTC=1535810503 in sec , "ts" shows UTC in msec

GPS 1PPS pulse on time (msec) 71539
{"ts":1535810503090,"values":{ "voltage": 3.299}}
{"ts":1535810503190,"values":{ "voltage": 3.299}}
GPS Epochtime= 1535810513  offset=234 UTC time: Sat Sep  1 14:01:53 2018
{"ts":1535810513234,"values":{ "offset": 234}}
{"ts":1535810513290,"values":{ "voltage": 3.299}}
{"ts":1535810513390,"values":{ "voltage": 3.299}}
{"ts":1535810513490,"values":{ "voltage": 3.299}}
{"ts":1535810513590,"values":{ "voltage": 3.299}}
{"ts":1535810513690,"values":{ "voltage": 3.299}}
{"ts":1535810513790,"values":{ "voltage": 3.299}}
{"ts":1535810513890,"values":{ "voltage": 3.299}}
{"ts":1535810513990,"values":{ "voltage": 3.299}}
GPS 1PPS pulse on time (msec) 72539

• GPS time decipline is done at every 10sec by default. (#define GPSTIMESET 10)
• GPIO_NUM_2 is used to light LED when NMEA provides UTC(in sec) to ESP32.
• (to do)This is an experimental code to observe the same phenomenon by multiple ESP32 board with sensors.

Hardware

• Hardware: ESP32-devkit-C

     GPIO_NUM_2 ------- LED pull down via 1KOhm (write 1 ... Light On to show GPS decipline) 
     GPIO_NUM_4 ------- LED pull down via 1KOhm (write 1 ... LIght On to show TinyGPS++ is working) 
     GPIO_NUM_34------Voltage monitor connected to CPU Vcc via 4.7KOhm ( ADC port as a sensor)
     GPIO_NUM_26------1PPS(TIMEPULSE) from NEO6M
     GPIO_NUM_17(TX)------NEO6M GPS RX (not used)
     GPIO_NUM_16(RX)------NEO6M GPS TX

License: Apache License v2

References

• [1 thingsboard] https://thingsboard.io/
• [2 TinyGPSplus/] http://arduiniana.org/libraries/tinygpsplus/
• [3 u-blox 6 Receiver Description Including Protocol Specification] https://www.u-blox.com/sites/default/files/products/documents/u-blox6_ReceiverDescrProtSpec_%28GPS.G6-SW-10018%29_Public.pdf
• [4 thingsboard JSON data format] https://thingsboard.io/docs/reference/http-api/

PubSubClient

• https://github.com/knolleary/pubsubclient

MQTT server with visiualization tools

• [https://thingsboard.io/] (https://thingsboard.io/)