support library for C027 helper functions for Buffer Pipes, Buffered Serial Port (rtos capable) and GPS parsing. It includes modem APIs for USSD, SMS and Sockets.

Dependents:   HTTPClient_Cellular_HelloWorld Cellular_HelloMQTT MbedSmartRestMain Car_Bon_car_module ... more

This library is intended to be used with u-blox products such as the C027 or a shield with u-blox cellular and GPS modules like the cellular and positioning shield from Embedded Artist.

For 2G/GSM and 3G/UMTS you need to:

  • have a SIM card and know its PIN number
  • need to know you network operators APN setting These setting should be passed to the connect or init and join functions. You can also extend the APN database in MDMAPN.h.

For CDMA products you need to make sure that you have provisioned and activated the modem with either Sprint or Verizon.

GPS.cpp

Committer:
mazgch
Date:
22 months ago
Revision:
139:fd9fe498f142
Parent:
95:8282dbbe1492

File content as of revision 139:fd9fe498f142:

#include "mbed.h"
#include <ctype.h>
#include "GPS.h"
#ifdef TARGET_UBLOX_C027
 #include "C027_api.h"
#endif

void GPSParser::powerOff(void)
{
    // set the gps into backup mode using the command RMX-LPREQ
    struct { unsigned long dur; unsigned long flags; } msg = {0/*endless*/,0/*backup*/};
    sendUbx(0x02, 0x41, &msg, sizeof(msg));
}

int GPSParser::_getMessage(Pipe<char>* pipe, char* buf, int len)
{
    int unkn = 0;
    int sz = pipe->size();
    int fr = pipe->free();
    if (len > sz)
        len = sz;
    while (len > 0)
    {
        // NMEA protocol
        pipe->set(unkn);
        int nmea = _parseNmea(pipe,len);
        if ((nmea != NOT_FOUND) && (unkn > 0))  
            return UNKNOWN | pipe->get(buf,unkn);
        if (nmea == WAIT && fr)                       
            return WAIT;
        if (nmea > 0)                           
            return NMEA | pipe->get(buf,nmea);
        // UBX protocol
        
        pipe->set(unkn);
        int ubx = _parseUbx(pipe,len);
        if ((ubx != NOT_FOUND) && (unkn > 0))   
            return UNKNOWN | pipe->get(buf,unkn);
        if (ubx == WAIT && fr)                        
            return WAIT;
        if (ubx > 0)                            
            return UBX | pipe->get(buf,ubx);
        
        // UNKNOWN
        unkn ++;
        len--;
    }
    if (unkn > 0)                      
        return UNKNOWN | pipe->get(buf,unkn); 
    return WAIT;
}

int GPSParser::_parseNmea(Pipe<char>* pipe, int len)
{
    int o = 0;
    int c = 0;
    char ch;
    if (++o > len)                      return WAIT;
    if ('$' != pipe->next())            return NOT_FOUND;
    // this needs to be extended by crc checking 
    for (;;)
    {
        if (++o > len)                  return WAIT;
        ch = pipe->next();
        if ('*' == ch)                  break; // crc delimiter 
        if (!isprint(ch))               return NOT_FOUND; 
        c ^= ch;
    }
    if (++o > len)                      return WAIT;
    ch = toHex[(c >> 4) & 0xF]; // high nibble
    if (ch != pipe->next())             return NOT_FOUND;
    if (++o > len)                      return WAIT;
    ch = toHex[(c >> 0) & 0xF]; // low nibble
    if (ch != pipe->next())             return NOT_FOUND;
    if (++o > len)                      return WAIT;
    if ('\r' != pipe->next())           return NOT_FOUND;
    if (++o > len)                      return WAIT;
    if ('\n' != pipe->next())           return NOT_FOUND;
    return o;
}

int GPSParser::_parseUbx(Pipe<char>* pipe, int l)
{
    int o = 0;
    if (++o > l)                return WAIT;
    if ('\xB5' != pipe->next()) return NOT_FOUND;   
    if (++o > l)                return WAIT;
    if ('\x62' != pipe->next()) return NOT_FOUND;
    o += 4;
    if (o > l)                  return WAIT;
    int i,j,ca,cb;
    i = pipe->next(); ca  = i; cb  = ca; // cls
    i = pipe->next(); ca += i; cb += ca; // id
    i = pipe->next(); ca += i; cb += ca; // len_lsb
    j = pipe->next(); ca += j; cb += ca; // len_msb 
    j = i + (j << 8);
    while (j--)
    {
        if (++o > l)            return WAIT;
        i = pipe->next(); 
        ca += i; 
        cb += ca;
    }
    ca &= 0xFF; cb &= 0xFF;
    if (++o > l)                return WAIT;
    if (ca != pipe->next())     return NOT_FOUND;
    if (++o > l)                return WAIT;
    if (cb != pipe->next())     return NOT_FOUND;
    return o;
}

int GPSParser::send(const char* buf, int len)
{
    return _send(buf, len);
}

int GPSParser::sendNmea(const char* buf, int len)
{
    char head[1] = { '$' };
    char tail[5] = { '*', 0x00/*crc_high*/, 0x00/*crc_low*/, '\r', '\n' };
    int i;
    int crc = 0;
    for (i = 0; i < len; i ++)
        crc ^= *buf++;
    i  = _send(head, sizeof(head));
    i += _send(buf, len);
    tail[1] = toHex[(crc > 4) & 0xF0];
    tail[2] = toHex[(crc > 0) & 0x0F];
    i += _send(tail, sizeof(tail));
    return i;
}

int GPSParser::sendUbx(unsigned char cls, unsigned char id, const void* buf /*= NULL*/, int len /*= 0*/)
{
    char head[6] = { 0xB5, 0x62, cls, id, len >> 0, len >> 8 };
    char crc[2];
    int i;
    int ca = 0;
    int cb = 0;
    for (i = 2; i < 6; i ++)
    {
        ca += head[i];
        cb += ca;
    }
    for (i = 0; i < len; i ++)
    {
        ca += ((char*)buf)[i];
        cb += ca; 
    }
    i  = _send(head, sizeof(head));
    i += _send(buf, len);
    crc[0] = ca & 0xFF;
    crc[1] = cb & 0xFF;
    i += _send(crc,  sizeof(crc));
    return i;
}

const char* GPSParser::findNmeaItemPos(int ix, const char* start, const char* end)
{
    // find the start
    for (; (start < end) && (ix > 0); start ++)
    {
        if (*start == ',')
            ix --;
    }
    // found and check bounds
    if ((ix == 0) && (start < end) && 
        (*start != ',') && (*start != '*') && (*start != '\r') && (*start != '\n'))
        return start;
    else 
        return NULL;
}

bool GPSParser::getNmeaItem(int ix, char* buf, int len, double& val)
{
    char* end = &buf[len];
    const char* pos = findNmeaItemPos(ix, buf, end);
    // find the start
    if (!pos)
        return false;
    val = strtod(pos, &end);
    // restore the last character
    return (end > pos);
}

bool GPSParser::getNmeaItem(int ix, char* buf, int len, int& val, int base /*=10*/)
{
    char* end = &buf[len];
    const char* pos = findNmeaItemPos(ix, buf, end);
    // find the start
    if (!pos)
        return false;
    val = (int)strtol(pos, &end, base);
    return (end > pos);
}

bool GPSParser::getNmeaItem(int ix, char* buf, int len, char& val)
{
    const char* end = &buf[len];
    const char* pos = findNmeaItemPos(ix, buf, end);
    // find the start
    if (!pos)
        return false;
    // skip leading spaces
    while ((pos < end) && isspace(*pos))
        pos++;
    // check bound
    if ((pos < end) && 
        (*pos != ',') && (*pos != '*') && (*pos != '\r') && (*pos != '\n'))
    {
        val = *pos;
        return true;
    }
    return false;
}

bool GPSParser::getNmeaAngle(int ix, char* buf, int len, double& val)
{
    char ch;
    if (getNmeaItem(ix,buf,len,val) && getNmeaItem(ix+1,buf,len,ch) && 
        ((ch == 'S') || (ch == 'N') || (ch == 'E') || (ch == 'W')))
    {
        val *= 0.01;
        int i = (int)val;
        val = (val - i) / 0.6 + i;
        if (ch == 'S' || ch == 'W')
            val = -val;
        return true;
    }
    return false;
}
                
const char GPSParser::toHex[] = { '0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F' };

// ----------------------------------------------------------------
// Serial Implementation 
// ----------------------------------------------------------------

GPSSerial::GPSSerial(PinName tx /*= GPSTXD*/, PinName rx /*= GPSRXD*/, int baudrate /*= GPSBAUD*/,
            int rxSize /*= 256*/, int txSize /*= 128*/) : 
            SerialPipe(tx, rx, baudrate, rxSize, txSize)
{
    baud(baudrate);
#ifdef TARGET_UBLOX_C027
    _onboard = (tx == GPSTXD) || (rx == GPSRXD);
    if (_onboard)
        c027_gps_powerOn(); 
#endif
}

GPSSerial::~GPSSerial(void)
{
    powerOff();
#ifdef TARGET_UBLOX_C027
    if (_onboard)
         c027_gps_powerOff();
#endif
}

bool GPSSerial::init(PinName pn)
{
    // send a byte to wakup the device again
    putc(0xFF);
    // wait until we get some bytes
    int size = _pipeRx.size();
    Timer timer;
    timer.start();
    while ((100 > timer.read_ms()) && (size == _pipeRx.size()))
        /* nothing / just wait */;
    return (size != _pipeRx.size());
}

int GPSSerial::getMessage(char* buf, int len)
{
    return _getMessage(&_pipeRx, buf, len);   
}

int GPSSerial::_send(const void* buf, int len)   
{ 
    return put((const char*)buf, len, true/*=blocking*/); 
}

// ----------------------------------------------------------------
// I2C Implementation 
// ----------------------------------------------------------------

GPSI2C::GPSI2C(PinName sda /*= GPSSDA*/, PinName scl /*= GPSSCL*/,
            unsigned char i2cAdr /*=GPSADR*/, int rxSize /*= 256*/) : 
            I2C(sda,scl),
            _pipe(rxSize),
            _i2cAdr(i2cAdr)
{
    frequency(100000);
#ifdef TARGET_UBLOX_C027
    _onboard = (sda == GPSSDA) && (scl == GPSSCL);
    if (_onboard)
        c027_gps_powerOn(); 
#endif
}

GPSI2C::~GPSI2C(void)
{
    powerOff();
#ifdef TARGET_UBLOX_C027
    if (_onboard)
         c027_gps_powerOff();
#endif
}

bool GPSI2C::init(PinName pn)
{
    if (pn != NC) {
        DigitalOut pin(pn, 0);
        ::wait_us(1);
        pin = 1;
        ::wait_ms(100);
    }
    return !I2C::write(_i2cAdr,&REGSTREAM,sizeof(REGSTREAM));
}

int GPSI2C::getMessage(char* buf, int len)
{
    // fill the pipe
    int sz = _pipe.free();
    if (sz) 
        sz = _get(buf, sz);
    if (sz) 
        _pipe.put(buf, sz);
    // now parse it
    return _getMessage(&_pipe, buf, len);   
}

int GPSI2C::send(const char* buf, int len)
{
    int sent = 0;
    if (len) 
    {
        if (!I2C::write(_i2cAdr,&REGSTREAM,sizeof(REGSTREAM),true))
            sent = send(buf, len);
        stop();
    }
    return sent;
}

int GPSI2C::sendNmea(const char* buf, int len)
{ 
    int sent = 0;
    if (!I2C::write(_i2cAdr,&REGSTREAM,sizeof(REGSTREAM),true))
        sent = GPSParser::sendNmea(buf, len);
    stop();
    return sent;
}

int GPSI2C::sendUbx(unsigned char cls, unsigned char id, const void* buf, int len)
{ 
    int sent = 0;
    if (!I2C::write(_i2cAdr,&REGSTREAM,sizeof(REGSTREAM),true))
        sent = GPSParser::sendUbx(cls, id, buf, len);
    I2C::stop();
    return sent;
}

int GPSI2C::_get(char* buf, int len)
{
    int read = 0;
    unsigned char sz[2] = {0,0};
    if (!I2C::write(_i2cAdr,&REGLEN,sizeof(REGLEN),true) && 
        !I2C::read(_i2cAdr,(char*)sz,sizeof(sz)))
    {
        int size = 256 * (int)sz[0] + sz[1];
        if (size > len)
            size = len;
        if (size > 0) 
        {
            if (!I2C::write(_i2cAdr,&REGSTREAM,sizeof(REGSTREAM),true) &&
                !I2C::read(_i2cAdr,buf,size)) {
                read = size;
            }
        }
    }
    return read;
}

int GPSI2C::_send(const void* buf, int len)
{ 
    return !I2C::write(_i2cAdr,(const char*)buf,len,true) ? len : 0; 
}

const char GPSI2C::REGLEN    = 0xFD;
const char GPSI2C::REGSTREAM = 0xFF;