Urgent help needed converting String to Unsigned Char.
Hi everyone, thursday I am presenting at school an Arduino project which will send a GPS location via Lorawan. I have 2 codes. One that receives the GPS frames from my GPS module and one that is used to send the data via Lorawan. The idea is to combine the two but I can't since the code for sending data via Lorawan wants an "Unsigned char variable" and that the code that receives GPS frames output these in Float variables.
GPS Code:
// Test code for Ultimate GPS Using Hardware Serial (e.g. GPS Flora or FeatherWing)
//
// This code shows how to listen to the GPS module via polling. Best used with
// Feathers or Flora where you have hardware Serial and no interrupt
//
// Tested and works great with the Adafruit GPS FeatherWing
// ------> https://www.adafruit.com/products/3133
// or Flora GPS
// ------> https://www.adafruit.com/products/1059
// but also works with the shield, breakout
// ------> https://www.adafruit.com/products/1272
// ------> https://www.adafruit.com/products/746
//
// Pick one up today at the Adafruit electronics shop
// and help support open source hardware & software! -ada
#include <Adafruit_GPS.h>
#include <avr/dtostrf.h>
// what's the name of the hardware serial port?
#define GPSSerial Serial1
// Connect to the GPS on the hardware port
Adafruit_GPS GPS(&GPSSerial);
// Set GPSECHO to 'false' to turn off echoing the GPS data to the Serial console
// Set to 'true' if you want to debug and listen to the raw GPS sentences
#define GPSECHO false
uint32_t timer = millis();
void setup()
{
//while (!Serial); // uncomment to have the sketch wait until Serial is ready
// connect at 115200 so we can read the GPS fast enough and echo without dropping chars
// also spit it out
Serial.begin(115200);
Serial.println("Adafruit GPS library basic test!");
// 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
GPS.begin(9600);
// uncomment this line to turn on RMC (recommended minimum) and GGA (fix data) including altitude
GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
// uncomment this line to turn on only the "minimum recommended" data
//GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCONLY);
// For parsing data, we don't suggest using anything but either RMC only or RMC+GGA since
// the parser doesn't care about other sentences at this time
// Set the update rate
GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ); // 1 Hz update rate
// For the parsing code to work nicely and have time to sort thru the data, and
// print it out we don't suggest using anything higher than 1 Hz
// Request updates on antenna status, comment out to keep quiet
GPS.sendCommand(PGCMD_ANTENNA);
delay(1000);
// Ask for firmware version
GPSSerial.println(PMTK_Q_RELEASE);
}
void loop() // run over and over again
{
// read data from the GPS in the 'main loop'
char c = GPS.read();
// if you want to debug, this is a good time to do it!
if (GPSECHO)
if (c) Serial.print(c);
// if a sentence is received, we can check the checksum, parse it...
if (GPS.newNMEAreceived()) {
// a tricky thing here is if we print the NMEA sentence, or data
// we end up not listening and catching other sentences!
// so be very wary if using OUTPUT_ALLDATA and trytng to print out data
Serial.println(GPS.lastNMEA()); // this also sets the newNMEAreceived() flag to false
if (!GPS.parse(GPS.lastNMEA())) // this also sets the newNMEAreceived() flag to false
return; // we can fail to parse a sentence in which case we should just wait for another
}
// if millis() or timer wraps around, we'll just reset it
if (timer > millis()) timer = millis();
// approximately every 2 seconds or so, print out the current stats
if (millis() - timer > 2000) {
timer = millis(); // reset the timer
if (GPS.fix) {
Serial.print("Location: ");
Serial.print(GPS.latitude, 4); Serial.print(GPS.lat);
Serial.print(", ");
Serial.print(GPS.longitude, 4); Serial.println(GPS.lon);
Serial.print(GPS.latitude);
}
}
}
When I open the monitor, it looks like this
https://i.redd.it/yrvdol9jtc231.png
Since I did not want unnecessary data to be sent ("Location:"), I tried to put in a string variable (that I named "stringfull") the only data I needed. That code worked and it looks like this:
// Test code for Ultimate GPS Using Hardware Serial (e.g. GPS Flora or FeatherWing)
//
// This code shows how to listen to the GPS module via polling. Best used with
// Feathers or Flora where you have hardware Serial and no interrupt
//
// Tested and works great with the Adafruit GPS FeatherWing
// ------> https://www.adafruit.com/products/3133
// or Flora GPS
// ------> https://www.adafruit.com/products/1059
// but also works with the shield, breakout
// ------> https://www.adafruit.com/products/1272
// ------> https://www.adafruit.com/products/746
//
// Pick one up today at the Adafruit electronics shop
// and help support open source hardware & software! -ada
#include <Adafruit_GPS.h>
#include <avr/dtostrf.h>
// what's the name of the hardware serial port?
#define GPSSerial Serial1
// Connect to the GPS on the hardware port
Adafruit_GPS GPS(&GPSSerial);
// Set GPSECHO to 'false' to turn off echoing the GPS data to the Serial console
// Set to 'true' if you want to debug and listen to the raw GPS sentences
#define GPSECHO false
uint32_t timer = millis();
String stringone = "";
String stringtwo = "";
String stringthree = "";
String stringfour = "";
String stringfull = "";
void setup()
{
//while (!Serial); // uncomment to have the sketch wait until Serial is ready
// connect at 115200 so we can read the GPS fast enough and echo without dropping chars
// also spit it out
Serial.begin(115200);
Serial.println("Adafruit GPS library basic test!");
// 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
GPS.begin(9600);
// uncomment this line to turn on RMC (recommended minimum) and GGA (fix data) including altitude
GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
// uncomment this line to turn on only the "minimum recommended" data
//GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCONLY);
// For parsing data, we don't suggest using anything but either RMC only or RMC+GGA since
// the parser doesn't care about other sentences at this time
// Set the update rate
GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ); // 1 Hz update rate
// For the parsing code to work nicely and have time to sort thru the data, and
// print it out we don't suggest using anything higher than 1 Hz
// Request updates on antenna status, comment out to keep quiet
GPS.sendCommand(PGCMD_ANTENNA);
delay(1000);
// Ask for firmware version
GPSSerial.println(PMTK_Q_RELEASE);
}
void loop() // run over and over again
{
// read data from the GPS in the 'main loop'
char c = GPS.read();
// if you want to debug, this is a good time to do it!
if (GPSECHO)
if (c) Serial.print(c);
// if a sentence is received, we can check the checksum, parse it...
if (GPS.newNMEAreceived()) {
// a tricky thing here is if we print the NMEA sentence, or data
// we end up not listening and catching other sentences!
// so be very wary if using OUTPUT_ALLDATA and trytng to print out data
Serial.println(GPS.lastNMEA()); // this also sets the newNMEAreceived() flag to false
if (!GPS.parse(GPS.lastNMEA())) // this also sets the newNMEAreceived() flag to false
return; // we can fail to parse a sentence in which case we should just wait for another
}
// if millis() or timer wraps around, we'll just reset it
if (timer > millis()) timer = millis();
// approximately every 2 seconds or so, print out the current stats
if (millis() - timer > 2000) {
timer = millis(); // reset the timer
if (GPS.fix) {
Serial.print("Location: ");
Serial.print(GPS.latitude, 4); Serial.print(GPS.lat);
Serial.print(", ");
Serial.print(GPS.longitude, 4); Serial.println(GPS.lon);
Serial.print(GPS.latitude);
stringone = GPS.latitude;
stringtwo = GPS.lat;
stringthree = GPS.longitude;
stringfour = GPS.lon;
stringfull = stringone + stringtwo + " ," + stringthree + stringfour;
Serial.print(stringfull);
}
}
}
This results in this:
https://i.redd.it/qhgms3couc231.png
The third line is what I want to send via the Lorawan code. The problem is that the Lorawan code I found only sends "Unsigned char" arrays and that my "stringfull" variable is a string variable.
The Lorawan code looks like this:
/*******************************************************************************
* Copyright (c) 2015 Thomas Telkamp and Matthijs Kooijman
* Adapted for Adafruit feather m0 LoRa by Stefan Huber
*
* Permission is hereby granted, free of charge, to anyone
* obtaining a copy of this document and accompanying files,
* to do whatever they want with them without any restriction,
* including, but not limited to, copying, modification and redistribution.
* NO WARRANTY OF ANY KIND IS PROVIDED.
*
* This example sends the actual battery voltage, using frequency and
* encryption settings matching those of the The Things Network.
*
* This uses OTAA (Over-the-air activation), where where a DevEUI and
* application key is configured, which are used in an over-the-air
* activation procedure where a DevAddr and session keys are
* assigned/generated for use with all further communication.
*
* Note: LoRaWAN per sub-band duty-cycle limitation is enforced (1% in
* g1, 0.1% in g2), but not the TTN fair usage policy (which is probably
* violated by this sketch when left running for longer)!
* To use this sketch, first register your application and device with
* the things network, to set or generate an AppEUI, DevEUI and AppKey.
* Multiple devices can use the same AppEUI, but each device has its own
* DevEUI and AppKey.
*
* Do not forget to define the radio type correctly in config.h.
*
*******************************************************************************/
#include <lmic.h>
#include <hal/hal.h>
#include <SPI.h>
#include <avr/dtostrf.h>
#include <stdlib.h>
#define VBATPIN A7
// This EUI must be in little-endian format, so least-significant-byte
// first. When copying an EUI from ttnctl output, this means to reverse
// the bytes. For TTN issued EUIs the last bytes should be 0xD5, 0xB3,
// 0x70.
static const u1_t PROGMEM APPEUI[8]={ 0x75, 0x6F, 0x6C, 0x69, 0x6F, 0x6D, 0x69, 0x6C };
void os_getArtEui (u1_t* buf) { memcpy_P(buf, APPEUI, 8);}
// This should also be in little endian format, see above.
static const u1_t PROGMEM DEVEUI[8]={ 0x02, 0x00, 0x00, 0x69, 0x6F, 0x6D, 0x69, 0x6C };
void os_getDevEui (u1_t* buf) { memcpy_P(buf, DEVEUI, 8);}
// This key should be in big endian format (or, since it is not really a
// number but a block of memory, endianness does not really apply). In
// practice, a key taken from ttnctl can be copied as-is.
// The key shown here is the semtech default key.
static const u1_t PROGMEM APPKEY[16] = { 0x6C, 0x4A, 0xA5, 0xDF, 0xEA, 0x91, 0x0B, 0x50, 0xC8, 0xDE, 0xBF, 0xBF, 0x3E, 0x94, 0x17, 0xE8 };
void os_getDevKey (u1_t* buf) { memcpy_P(buf, APPKEY, 16);}
char mydata[16];
static osjob_t sendjob;
// Schedule TX every this many seconds (might become longer due to duty
// cycle limitations).
const unsigned TX_INTERVAL = 7;
// Pin mapping
const lmic_pinmap lmic_pins = {
.nss = 8,
.rxtx = LMIC_UNUSED_PIN,
.rst = LMIC_UNUSED_PIN,
.dio = {3,6,LMIC_UNUSED_PIN},
};
void onEvent (ev_t ev) {
Serial.print(os_getTime());
Serial.print(": ");
switch(ev) {
case EV_SCAN_TIMEOUT:
Serial.println(F("EV_SCAN_TIMEOUT"));
break;
case EV_BEACON_FOUND:
Serial.println(F("EV_BEACON_FOUND"));
break;
case EV_BEACON_MISSED:
Serial.println(F("EV_BEACON_MISSED"));
break;
case EV_BEACON_TRACKED:
Serial.println(F("EV_BEACON_TRACKED"));
break;
case EV_JOINING:
Serial.println(F("EV_JOINING"));
break;
case EV_JOINED:
Serial.println(F("EV_JOINED"));
// Disable link check validation (automatically enabled
// during join, but not supported by TTN at this time).
LMIC_setLinkCheckMode(0);
break;
case EV_RFU1:
Serial.println(F("EV_RFU1"));
break;
case EV_JOIN_FAILED:
Serial.println(F("EV_JOIN_FAILED"));
break;
case EV_REJOIN_FAILED:
Serial.println(F("EV_REJOIN_FAILED"));
break;
break;
case EV_TXCOMPLETE:
Serial.println(F("EV_TXCOMPLETE (includes waiting for RX windows)"));
if (LMIC.txrxFlags & TXRX_ACK)
Serial.println(F("Received ack"));
if (LMIC.dataLen) {
Serial.println(F("Received "));
Serial.println(LMIC.dataLen);
Serial.println(F(" bytes of payload"));
}
// Schedule next transmission
os_setTimedCallback(&sendjob, os_getTime()+sec2osticks(TX_INTERVAL), do_send);
break;
case EV_LOST_TSYNC:
Serial.println(F("EV_LOST_TSYNC"));
break;
case EV_RESET:
Serial.println(F("EV_RESET"));
break;
case EV_RXCOMPLETE:
// data received in ping slot
Serial.println(F("EV_RXCOMPLETE"));
break;
case EV_LINK_DEAD:
Serial.println(F("EV_LINK_DEAD"));
break;
case EV_LINK_ALIVE:
Serial.println(F("EV_LINK_ALIVE"));
break;
default:
Serial.println(F("Unknown event"));
break;
}
}
void readValues(unsigned char *vals) {
// Payload format Bytes: [(Bat-Voltage - 2) * 100]
double measuredvbat = analogRead(VBATPIN);
measuredvbat *= 2; // we divided by 2, so multiply back
measuredvbat *= 3.3; // Multiply by 3.3V, our reference voltage
measuredvbat /= 1024; // convert to voltage
Serial.print("VBat: " ); Serial.println(measuredvbat);
measuredvbat -= 2; // offset by -2
measuredvbat *= 100; //make it centi volts
Serial.print("VBat in CVolts-2: " ); Serial.println(measuredvbat);
vals[0] = (unsigned char)measuredvbat; //we're unsigned
}
void do_send(osjob_t* j){
// Check if there is not a current TX/RX job running
if (LMIC.opmode & OP_TXRXPEND) {
Serial.println(F("OP_TXRXPEND, not sending"));
} else {
// Prepare upstream data transmission at the next possible time.
unsigned char payload;
unsigned char message[12] = "arduino";
readValues(&payload);
LMIC_setTxData2(1, message, 12, 0);
Serial.println(F("Packet queued"));
Serial.println(payload);
}
// Next TX is scheduled after TX_COMPLETE event.
}
void setup() {
Serial.begin(9600);
delay(10000);
Serial.println(F("Starting"));
// LMIC init
os_init();
// Reset the MAC state. Session and pending data transfers will be discarded.
LMIC_reset();
LMIC_setClockError(MAX_CLOCK_ERROR * 1 / 100);
// Start job (sending automatically starts OTAA too)
do_send(&sendjob);
// Show on device LED that we are ready
pinMode(13, OUTPUT);
digitalWrite(13, HIGH);
}
void loop() {
os_runloop_once();
}
This part of the code is where you input the variable you want to send: (LMIC_setTxData2(1, message, 12, 0):
I'd want to input "stringfull" where "message" is but it doesn't work.
Any help is appreciated. Thanks!!!
Posted Jun 4, 2019, 3:13 PM UTC
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