====== UART Communication between the flipper and a GPS Module : Ublox SAM-M8Q ======

----

tags: flipper, GPS, Ublox SAM-M8Q, Arduino, UART

**This is an example code of UART communication between a GPS Module and the flipper board.**

===== - Requirements =====
Version  0.2.0 or higher of the Strataggem nRF52 arduino board package (see updating the bsp ).

===== - Schematics and Wiring =====
{{:products:flipper:800px-schema_xlbee.png|}}

On a basic flipper board  configuration :

  * Xlbee connector has its UART0_TX connected to the MCU UART0_RX
  * Xlbee connector has its UART0_RX connected to the MCU UART0_TX
  * An Xlbee compatible module is powered when MCU_XLB_EN is high

The GPS module is a [[https://www.u-blox.com/sites/default/files/SAM-M8Q_DataSheet_%28UBX-16012619%29.pdf|Ublox SAM-M8Q]] .

The sensor is wired on UART0 communication bus so we will use Serial1 instance (if we were using UART1 it would have been Serial2 instance, see [[products:flipper:arduino_bus_references|flipper arduino bus references]] ). The basic baudrate of the module is 9600 bps (see {{ :products:flipper:sam-m8q_datasheet_ubx-16012619_.pdf |datasheet}}). We start our set up by setting MCU_XLB_EN = XLB_EN in arduino IDE (see gpio arduino name table) .



===== - Arduino Code =====

The module is sending nmea messages on the serial bus, to parse those messages we used the [[https://github.com/mikalhart/TinyGPSPlus|TinyGPSPlus library]] by mikalhart.


Following code has been modified from this [[https://github.com/mikalhart/TinyGPSPlus/blob/master/examples/DeviceExample/DeviceExample.ino|example]] provided in the library.

<file cpp flipper_SAM_M8Q__GPS.ino>
#include <TinyGPS++.h>

// The TinyGPS++ object
TinyGPSPlus gps;

void setup()
{
  //enabling XLB_VDD power rail to give power to the module
  pinMode(XLB_EN, OUTPUT);
  digitalWrite(XLB_EN, HIGH);
  delay(1000);
  Serial.begin(115200);
  Serial1.begin(9600);
  
}

void loop()
{
  // This sketch displays information every time a new sentence is correctly encoded.
  while (Serial1.available() > 0){
    if (gps.encode(Serial1.read())){
      displayInfo();
    }
  }

  if (millis() > 5000 && gps.charsProcessed() < 10)
  {
    Serial.println(F("No GPS detected: check wiring."));
    while(true);
  }
}

void displayInfo()
{
  Serial.print(F("Location: ")); 
  if ( gps.location.isValid() && gps.location.age() < 5000 )
  {
    Serial.print(gps.location.lat(), 6);
    Serial.print(F(","));
    Serial.print(gps.location.lng(), 6);
    digitalWrite(LED_BLUE,HIGH);
    delay(200);
    digitalWrite(LED_BLUE,LOW);
  }
  else
  {
    Serial.print(F("INVALID"));
  }

  Serial.print(F("  Date/Time: "));
  if (gps.date.isValid())
  {
    Serial.print(gps.date.month());
    Serial.print(F("/"));
    Serial.print(gps.date.day());
    Serial.print(F("/"));
    Serial.print(gps.date.year());
  }
  else
  {
    Serial.print(F("INVALID"));
  }

  Serial.print(F(" "));
  if (gps.time.isValid())
  {
    if (gps.time.hour() < 10) Serial.print(F("0"));
    Serial.print(gps.time.hour());
    Serial.print(F(":"));
    if (gps.time.minute() < 10) Serial.print(F("0"));
    Serial.print(gps.time.minute());
    Serial.print(F(":"));
    if (gps.time.second() < 10) Serial.print(F("0"));
    Serial.print(gps.time.second());
    Serial.print(F("."));
    if (gps.time.centisecond() < 10) Serial.print(F("0"));
    Serial.print(gps.time.centisecond());
  }
  else
  {
    Serial.print(F("INVALID"));
  }

  Serial.println();
}
</file>