Diff: GPS_I2C.cpp

Revision:

0:f4c7ece483fe

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GPS_I2C.cpp	Fri Dec 27 15:32:37 2019 +0000
@@ -0,0 +1,63 @@
+#include "GPS_I2C.h"
+
+GPS_I2C::GPS_I2C(PinName sda, PinName scl, uint32_t freq)
+    : _i2c(sda, scl), _freq(freq)
+{
+    _i2c.frequency(_freq);
+}
+
+GPS_I2C::~GPS_I2C() {}
+/*****************************************************/
+bool    GPS_I2C::begin()
+{
+    int ack;
+
+    _head = 0;
+    _tail = 0;
+
+    ack = _i2c.read(MT333x_ADDR << 1, (char*)gpsData, 1);
+    //Verify if module is connected
+    if( ack != 0 ) return false;
+    else           return true;
+}
+
+void    GPS_I2C::check()
+{
+    uint8_t packetData[MAX_PACKET_SIZE];
+
+    for (uint8_t x = 0 ; x < MAX_PACKET_SIZE ; x++) {
+        packetData[x] = 0x0A; //Fill with garbage byte
+    }
+
+    _i2c.read(MT333x_ADDR << 1, ((char*)packetData), MAX_PACKET_SIZE);
+
+    for (uint8_t x = 0 ; x < MAX_PACKET_SIZE ; x++) {
+        if (packetData[x] != 0x0A) {
+            gpsData[_head++] = packetData[x];
+            if (_head == MAX_PACKET_SIZE) _head = 0; //Wrap variable
+        }
+    }
+}
+
+uint8_t GPS_I2C::available()
+{
+    //If tail=head then no new data is available in the local buffer
+    //So now check to see if the module has anything new in its buffer
+    if (_tail == _head) {
+        check(); //Check to module to see if new I2C bytes are available
+    }
+
+    //Return new data count
+    if (_head > _tail) return (_head - _tail);
+    if (_tail > _head) return (MAX_PACKET_SIZE - _tail + _head);
+    return (0); //No data available
+}
+uint8_t GPS_I2C::read()
+{
+    if (_tail != _head) {
+        uint8_t datum = gpsData[_tail++];
+        if (_tail == MAX_PACKET_SIZE) _tail = 0; //Wrap variable
+        return (datum);
+    } else
+        return (0); //No new data
+}
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