“I made an Arduino library allowing simple communication with uECG device using nRF24 module - minimal example takes just a few lines.
Some time ago I posted a couple of projects demonstrating how to get data from uECG device - but they had quite a lot of messy code and still were using only basic data from it. So finally I wrote an Arduino library that makes this way simpler and much more reliable, here it is: https://github.com/ultimaterobotics/uECG_library (please note that you also need to install RF24 library from Library Manager, and if you want to show data on OLED like in this project - also Adafruit’s SSD1306 library).
Schematics is the same as for any other project using nRF24 module and OLED: nRF24 is connected to Arduino’s SPI bus (D13, D12, D11) and two arbitrary pins for module CS and CE lines - I’ve chosen D10 and D9 for convenience. The only important point: nRF24 module must be connected to 3.3V line, not to 5V! It also helps a lot to add 1uF or 10uF capacitor between 3.3V and GND - those nRF24 modules require a stable voltage which Arduino can’t always provide on its 3.3V line, capacitors help with that.
OLED is connected via I2C - SDA to A4, SCL to A5, and powered from 5V line. In my case, OLED module had in-built resistors for I2C protocol. In case if your module doesn’t have them - you need to add 4.7k resistors from SDA to 3.3V and from SCL to 3.3V, although most modules I’ve seen recently have them already.”