Notes

this Repo is a fork of the original project and adapts the previous work to work with a heltec ESP32 wifi kit with builtin screen.

the original project made use of different pins (for wemos lolin 32?) and i have opted to fix all the hardcoded pin values i can find to be paramaterized at the begining to easily adapt it to a different board.

i am using a GT-U7 GPS module , heltec Wifi kit V2 and a lithium ion cell and have ommited the RTC for now the pins used in my configuration

I²C:

GPIO PIN	Function
GPIO 15	SCL
GPIO 04	SDA
GPIO 04	oled reset

GPS:

GPIO PIN	Function
GPIO 13	UART RX
GPIO 02	UART TX
GPIO 26	PPS Interrupt

buttons

GPIO PIN	Function
GPIO 0	screen select (label prg on board)

Getting started

you probably just need to clone this repo, and build in platform io it should pull all the required libs for you. make sure you have the root of your project be at the firmware folder i should have tidyd that up to but didn't want to change much incase i need to adapt this to push back to the original project

it will likely boot loop untill you load in the file system image so make sure you navigate to and run

1. platformio -> project tasks helteck wifi kit 32_v2 -> Platform-> Build Filesystem Image
2. platformio -> project tasks helteck wifi kit 32_v2 -> Platform-> Upload Fileystem Image

details if you are using something different can be found at something ike https://randomnerdtutorials.com/esp32-vs-code-platformio-spiffs/

Future plans

i may add additional screens (number sats in view quality of fix a blank screen ) and revise how the screens are handled (big old messy function in the main.cpp )

ORIGINAL Writeup

180662 mini NTP with ESP32

License: GPLv3

Firmware for Elektorproject 180662 is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Firmware for Elektorproject 180662.  If not, see <https://www.gnu.org/licenses/>.

Code for the GPS based NTP with ESP32. This software uses a Wemos LoLin ESP32 OLED as base. The OLED used is a SSD1307 based one attached to the i²C Bus. This board can be purchased at ( https://www.elektor.com/wemos-lolin-esp32-oled-module-with-wifi ). As GPS receiver this one is used in the build ( https://www.elektor.com/open-smart-gps-serial-gps-module-for-arduino-apm2-5-flight-control )

Software

The software is written using the arduino framwork for the ESP32. Also you need to compile the code following libraries to be present:

• U8G2 by oliver
• Time by Michael Magolis
• Ticker by Bert Melis
• TinyGPS++ ( https://github.com/mikalhart/TinyGPSPlus )
• RTCLib by Adafruit
• ArduinoJson 6.10.0
• CRC32 by Christopher Baker

Compile and upload the code to your ESP32. Also upload the webpages.

GPIO Mapping

For the GPIOs used these are not the arduino default ones, as they needed to be modified for the OLED. The following pins are used:

I²C:

GPIO PIN	Function
GPIO04	SCL
GPIO05	SDA

GPS:

GPIO PIN	Function
GPIO13	UART RX
GPIO15	UART TX
GPIO25	PPS Interrupt

For more inforamtion have a look at: https://www.elektormagazine.com/labs/mini-ntp-server-with-gps