Reading MMA8452Q Accelerometer Data on the Sparkfun nRF52840 Mini

Development Boards MicroMod
1

Hello,

I have my nRF52840 hooked up, was successful at sending 1’s and 0’s over Rx from the nRF Connect app for IOS. However, under the “UART TX characteristic” > “Properties,” it says “Write and Write without response.” So I am unable to see the status of the light from the app.

I am also able to read accelerometer data from the on the SparkFun MMA8452Q on the serial monitor. I would like to be able to read the accelerometer data remotely. Can anyone help with this?

Here is the code I am using:

/* BLE Example for SparkFun Pro nRF52840 Mini 
 *  
 *  This example demonstrates how to use the Bluefruit
 *  library to both send and receive data to the
 *  nRF52840 via BLE.
 *  
 *  Using a BLE development app like Nordic's nRF Connect
 *  https://www.nordicsemi.com/eng/Products/Nordic-mobile-Apps/nRF-Connect-for-Mobile
 *  The BLE UART service can be written to to turn the
 *  on-board LED on/off, or read from to monitor the 
 *  status of the button.
 *  
 *  See the tutorial for more information:
 *  https://learn.sparkfun.com/tutorials/nrf52840-development-with-arduino-and-circuitpython#arduino-examples  
*/
#include <bluefruit.h>
#include <Wire.h>                 // Must include Wire library for I2C
#include "SparkFun_MMA8452Q.h"    // Click here to get the library: http://librarymanager/All#SparkFun_MMA8452Q

MMA8452Q accel;                   // create instance of the MMA8452 class

BLEUart bleuart; // uart over ble

// Define hardware: LED and Button pins and states
const int LED_PIN = 7;
#define LED_OFF LOW
#define LED_ON HIGH

const int BUTTON_PIN = 13;
#define BUTTON_ACTIVE LOW
int lastButtonState = -1;

void setup() {
  // Initialize hardware:
  Serial.begin(9600); // Serial is the USB serial port
    Serial.println("MMA8452Q Basic Reading Code!");
      Wire.begin();

  if (accel.begin() == false) {
    Serial.println("Not Connected. Please check connections and read the hookup guide.");
    while (1);
  }
  pinMode(LED_PIN, OUTPUT); // Turn on-board blue LED off
  digitalWrite(LED_PIN, LED_OFF);
  pinMode(BUTTON_PIN, INPUT);
  Serial.println("Adafruit MPU6050 test!");

  // Uncomment the code below to disable sharing
  // the connection LED on pin 7.
  //Bluefruit.autoConnLed(false);

  // Initialize Bluetooth:
  Bluefruit.begin();
  // Set max power. Accepted values are: -40, -30, -20, -16, -12, -8, -4, 0, 4
  Bluefruit.setTxPower(4);
  Bluefruit.setName("SparkFun_nRF52840");
  bleuart.begin();

  // Start advertising device and bleuart services
  Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
  Bluefruit.Advertising.addTxPower();
  Bluefruit.Advertising.addService(bleuart);
  Bluefruit.ScanResponse.addName();

  Bluefruit.Advertising.restartOnDisconnect(true);
  // Set advertising interval (in unit of 0.625ms):
  Bluefruit.Advertising.setInterval(32, 244);
  // number of seconds in fast mode:
  Bluefruit.Advertising.setFastTimeout(30);
  Bluefruit.Advertising.start(0);  
}

void loop() {
  // If data has come in via BLE:
  if (bleuart.available()) {
    uint8_t c;
    // use bleuart.read() to read a character sent over BLE
    c = (uint8_t) bleuart.read();
    // Print out the character for debug purposes:
    Serial.write(c);

    // If the character is one of our expected values,
    // do something:
    switch (c) {
      // 0 number or character, turn the LED off:
      case 0:
      case '0':
        digitalWrite(LED_PIN, LED_OFF);
        break;
      // 1 number or character, turn the LED on:
      case 1:
      case '1':
        digitalWrite(LED_PIN, LED_ON);
        break;
      default:
        break;
    }
  }
  if (accel.available()) {      // Wait for new data from accelerometer
    // Acceleration of x, y, and z directions in g units
    Serial.print(accel.getCalculatedX(), 3);
    Serial.print("\t");
    Serial.print(accel.getCalculatedY(), 3);
    Serial.print("\t");
    Serial.print(accel.getCalculatedZ(), 3);
    Serial.println();
  }
  // If our button state has changed:
  int buttonState = digitalRead(BUTTON_PIN);
  if (buttonState != lastButtonState) {
    lastButtonState = buttonState;
    // Write the new button state to the bleuart TX char
    bleuart.write(!buttonState);
  }
}