Interfacing of GSM 800 L Modules with Arduino.
What is a GSM Module ?
The SIM800L is a cheap and portable GSM breakout board with all the capabilities of the larger SIM900 shields. In this Arduino SIM800L tutorial, I will help you get started with this nifty device. Sending and receiving texts with your Arduino have never been easier!
SIM800L Introduction
Here are the features of the SIM800L breakout board:
2G quad-band @ 850/900/1800/1900 MHz
Receive and make calls using the speaker and microphone outputs
Receive and send SMS
Connect to the Internet via GPRS
Listen to FM radio broadcasts
Accepts AT Commands
From the specification of SIM800L we would able to find out that its:
Operating Voltage: 3.3 - 5 Volts
Recommended voltage: 3.4 - 4.4 Volts
Recommended Current: 1 – 2 Amp
Therefore, if we use voltages below 3.4, either the SIM800L will not work or it will work but not all its features are responding (e.g unable to read SIM card). But if use voltage equal to its MAXIMUM operating voltage, the module might heat up and then got destroyed, or if we use ABOVE operating voltage, well, it will absolutely destroy the module. Most important, we should not supply a current above 2 Amp (e.g 5 Amp) to the module, it will destroy the module even if your voltage is in 3.4 - 4.4 volts range.
But here in our tutorial, you will observe that the module get 5V supply from arduino. That’s sound risky, but as my measurement, computation and observation, 5V pin in Arduino generate current from 500mA -1 Amp which gives a maximum power of 5 Watts. 5 watts qualifies from recommended power which would not cause the module to heat up or destroyed. That’s why 5V pin in Arduino qualifies as a supply voltage.
If the power to the SIM800L is enough, the on-board LED starts blinking. The frequency of the blinking means something:
Every second: searching for a network.
Every three seconds: connected to a network.
Twice per second: connected through GPRS.
Antennas are essential for this kind of module especially if your project is indoors. Without an antenna, there would not be enough transmitting power for the SIM800L to perform GSM services such as calls and SMS.
Material Required: Material Quantity
Arduino Uno 1
SIM 800L 1
Jumper cables 6
Breadboard 1
Pinout Diagram:
Circuit Diagram:
Note: Make sure you already inserted your SIM card before powering the module. If not, you will not see any changes in the module LED indicator.
SIM800 VCC ↔ Arduino 5v
SIM800 GND ↔ Arduino GND
SIM800 SIM_TXD ↔ Arduino pin 3
SIM800 SIM_RXD ↔ Arduino pin 2
Step 2: Code
Download and Add Adafriut Fona library to your Arduino library.
Then open and upload the Fonatest sample code from Adafruit Fona.
Open Serial monitor then change baudrate to 115200 and choose NL & CR.
Then you'll see Menu of test setup, choose anything you want to test (e.g send and receive message).
Tested Programming Code:
#include "Adafruit_FONA.h" #define FONA_RX 2 #define FONA_TX 3 #define FONA_RST 4 // this is a large buffer for replies char replybuffer[255]; // We default to using software serial. If you want to use hardware serial // (because softserial isnt supported) comment out the following three lines // and uncomment the HardwareSerial line
#include <SoftwareSerial.h> SoftwareSerial fonaSS = SoftwareSerial(FONA_TX, FONA_RX);
SoftwareSerial *fonaSerial = &fonaSS; // Hardware serial is also possible! // HardwareSerial *fonaSerial = &Serial1; // Use this for FONA 800 and 808s Adafruit_FONA fona = Adafruit_FONA(FONA_RST); // Use this one for FONA 3G //Adafruit_FONA_3G fona = Adafruit_FONA_3G(FONA_RST);
uint8_t readline(char *buff, uint8_t maxbuff, uint16_t timeout = 0);
uint8_t type; void setup() {
while (!Serial); Serial.begin(115200);
Serial.println(F("FONA basic test")); Serial.println(F("Initializing.. (May take 3 seconds)")); fonaSerial->begin(4800); if (! fona.begin(*fonaSerial)) {
Serial.println(F("Couldn't find FONA"));
while (1); } type = fona.type();
Serial.println(F("FONA is OK"));
Serial.print(F("Found "));
switch (type) { case FONA800L:
Serial.println(F("FONA 800L")); break;
case FONA800H: Serial.println(F("FONA 800H")); break;
case FONA808_V1: Serial.println(F("FONA 808 (v1)")); break;
case FONA808_V2: Serial.println(F("FONA 808 (v2)")); break;
case FONA3G_A: Serial.println(F("FONA 3G (American)")); break;
case FONA3G_E: Serial.println(F("FONA 3G (European)")); break;
default: Serial.println(F("???")); break; } // Print module IMEI number. char imei[16] = {0}; // MUST use a 16 character buffer for IMEI!
uint8_t imeiLen = fona.getIMEI(imei); if (imeiLen > 0) { Serial.print("Module IMEI: "); Serial.println(imei); } // Optionally configure a GPRS APN, username, and password. // You might need to do this to access your network's GPRS/data // network. Contact your provider for the exact APN, username, // and password values. Username and password are optional and // can be removed, but APN is required. //fona.setGPRSNetworkSettings(F("your APN"), F("your username"), F("your password")); // Optionally configure HTTP gets to follow redirects over SSL. // Default is not to follow SSL redirects, however if you uncomment // the following line then redirects over SSL will be followed. //fona.setHTTPSRedirect(true);
printMenu(); } void printMenu(void) { Serial.println(F(" ")); Serial.println(F("[?] Print this menu")); Serial.println(F("[a] read the ADC 2.8V max (FONA800 & 808)"));
Serial.println(F("[b] read the Battery V and % charged")); Serial.println(F("[C] read the SIM CCID")); Serial.println(F("[U] Unlock SIM with PIN code")); Serial.println(F("[i] read RSSI"));
Serial.println(F("[n] get Network status"));
Serial.println(F("[v] set audio Volume"));
Serial.println(F("[V] get Volume")); Serial.println(F("[H] set Headphone audio (FONA800 & 808)"));
Serial.println(F("[e] set External audio (FONA800 & 808)")); Serial.println(F("[T] play audio Tone")); Serial.println(F("[P] PWM/Buzzer out (FONA800 & 808)")); // FM (SIM800 only!) Serial.println(F("[f] tune FM radio (FONA800)")); Serial.println(F("[F] turn off FM (FONA800)")); Serial.println(F("[m] set FM volume (FONA800)")); Serial.println(F("[M] get FM volume (FONA800)")); Serial.println(F("[q] get FM station signal level (FONA800)")); // Phone Serial.println(F("[c] make phone Call"));
Serial.println(F("[A] get call status"));
Serial.println(F("[h] Hang up phone"));
Serial.println(F("[p] Pick up phone")); // SMS Serial.println(F("[N] Number of SMSs"));
Serial.println(F("[r] Read SMS #"));
Serial.println(F("[R] Read All SMS"));
Serial.println(F("[d] Delete SMS #"));
Serial.println(F("[s] Send SMS")); Serial.println(F("[u] Send USSD"));
// Time Serial.println(F("[y] Enable network time sync (FONA 800 & 808)"));
Serial.println(F("[Y] Enable NTP time sync (GPRS FONA 800 & 808)"));
Serial.println(F("[t] Get network time")); // GPRS Serial.println(F("[G] Enable GPRS"));
Serial.println(F("[g] Disable GPRS"));
Serial.println(F("[l] Query GSMLOC (GPRS)")); Serial.println(F("[w] Read webpage (GPRS)")); Serial.println(F("[W] Post to website (GPRS)")); // GPS if ((type == FONA3G_A) || (type == FONA3G_E) || (type == FONA808_V1) || (type == FONA808_V2)) {
Serial.println(F("[O] Turn GPS on (FONA 808 & 3G)")); Serial.println(F("[o] Turn GPS off (FONA 808 & 3G)")); Serial.println(F("[L] Query GPS location (FONA 808 & 3G)")); if (type == FONA808_V1) { Serial.println(F("[x] GPS fix status (FONA808 v1 only)")); } Serial.println(F("[E] Raw NMEA out (FONA808)")); } Serial.println(F("[S] create Serial passthru tunnel")); Serial.println(F(" ")); Serial.println(F("")); } void loop() { Serial.print(F("FONA> "));
while (! Serial.available() ) {
if (fona.available()) { Serial.write(fona.read()); } } char command = Serial.read();
Serial.println(command);
switch (command) { case '?': { printMenu();
break; } case 'a': { // read the ADC
uint16_t adc; if (! fona.getADCVoltage(&adc))
{ Serial.println(F("Failed to read ADC")); } else { Serial.print(F("ADC = ")); Serial.print(adc); Serial.println(F(" mV")); } break; } case 'b': { // read the battery voltage and percentage
uint16_t vbat; if (! fona.getBattVoltage(&vbat)) {
Serial.println(F("Failed to read Batt")); } else { Serial.print(F("VBat = ")); Serial.print(vbat); Serial.println(F(" mV")); } if (! fona.getBattPercent(&vbat)) {
Serial.println(F("Failed to read Batt")); } else { Serial.print(F("VPct = ")); Serial.print(vbat);Serial.println(F("%")); } break; } case 'U': { // Unlock the SIM with a PIN code
char PIN[5];
flushSerial(); Serial.println(F("Enter 4-digit PIN"));
readline(PIN, 3); Serial.println(PIN);
Serial.print(F("Unlocking SIM card: "));
if (! fona.unlockSIM(PIN)) {
Serial.println(F("Failed")); } else {
Serial.println(F("OK!")); } break; } case 'C': { // read the CCID fona.getSIMCCID(replybuffer); // make sure replybuffer is at least 21 bytes!
Serial.print(F("SIM CCID = ")); Serial.println(replybuffer); break; } case 'i': { // read the RSSI uint8_t n = fona.getRSSI(); int8_t r; Serial.print(F("RSSI = ")); Serial.print(n); Serial.print(": "); if (n == 0) r = -115; if (n == 1) r = -111; if (n == 31) r = -52; if ((n >= 2) && (n <= 30)) { r = map(n, 2, 30, -110, -54); } Serial.print(r); Serial.println(F(" dBm")); break; } case 'n': { // read the network/cellular status uint8_t n = fona.getNetworkStatus();
Serial.print(F("Network status ")); Serial.print(n); Serial.print(F(": ")); if (n == 0) Serial.println(F("Not registered")); if (n == 1) Serial.println(F("Registered (home)")); if (n == 2) Serial.println(F("Not registered (searching)")); if (n == 3) Serial.println(F("Denied")); if (n == 4) Serial.println(F("Unknown")); if (n == 5) Serial.println(F("Registered roaming")); break; } /*** Audio ***/ case 'v': { // set volume flushSerial(); if ( (type == FONA3G_A) || (type == FONA3G_E) ) { Serial.print(F("Set Vol [0-8] ")); } else { Serial.print(F("Set Vol % [0-100] ")); } uint8_t vol = readnumber(); Serial.println(); if (! fona.setVolume(vol)) { Serial.println(F("Failed")); } else { Serial.println(F("OK!")); } break; } case 'V': { uint8_t v = fona.getVolume(); Serial.print(v); if ( (type == FONA3G_A) || (type == FONA3G_E) ) { Serial.println(" / 8"); } else { Serial.println("%"); } break;
} case 'H': { // Set Headphone output if (! fona.setAudio(FONA_HEADSETAUDIO)) { Serial.println(F("Failed")); } else { Serial.println(F("OK!")); } fona.setMicVolume(FONA_HEADSETAUDIO, 15); break; } case 'e': { // Set External output if (! fona.setAudio(FONA_EXTAUDIO)) { Serial.println(F("Failed")); } else { Serial.println(F("OK!")); } fona.setMicVolume(FONA_EXTAUDIO, 10); break; } case 'T': { // play tone flushSerial(); Serial.print(F("Play tone #")); uint8_t kittone = readnumber(); Serial.println(); // play for 1 second (1000 ms) if (! fona.playToolkitTone(kittone, 1000)) { Serial.println(F("Failed")); } else { Serial.println(F("OK!")); } break; }
case 'f': { // get freq flushSerial(); Serial.print(F("FM Freq (eg 1011 == 101.1 MHz): ")); uint16_t station = readnumber(); Serial.println(); // FM radio ON using headset if (fona.FMradio(true, FONA_HEADSETAUDIO)) { Serial.println(F("Opened")); } if (! fona.tuneFMradio(station)) { Serial.println(F("Failed")); } else { Serial.println(F("Tuned")); } break; } case 'F': { // FM radio off if (! fona.FMradio(false)) { Serial.println(F("Failed")); } else { Serial.println(F("OK!")); } break; } case 'm': { // Set FM volume. flushSerial(); Serial.print(F("Set FM Vol [0-6]:")); uint8_t vol = readnumber(); Serial.println(); if (!fona.setFMVolume(vol)) { Serial.println(F("Failed")); } else { Serial.println(F("OK!")); } break;
case 'M': { // Get FM volume. uint8_t fmvol = fona.getFMVolume(); if (fmvol < 0) { Serial.println(F("Failed")); } else { Serial.print(F("FM volume: ")); Serial.println(fmvol, DEC); } break; } case 'q': { // Get FM station signal level (in decibels). flushSerial(); Serial.print(F("FM Freq (eg 1011 == 101.1 MHz): ")); uint16_t station = readnumber(); Serial.println(); int8_t level = fona.getFMSignalLevel(station); if (level < 0) { Serial.println(F("Failed! Make sure FM radio is on (tuned to station).")); } else { Serial.print(F("Signal level (dB): ")); Serial.println(level, DEC); } break; } /*** PWM ***/ case 'P': { // PWM Buzzer output @ 2KHz max flushSerial(); Serial.print(F("PWM Freq, 0 = Off, (1-2000): ")); uint16_t freq = readnumber(); Serial.println(); if (! fona.setPWM(freq)) {
break; } /*** Call ***/ case 'c': { // call a phone! char number[30]; flushSerial(); Serial.print(F("Call #")); readline(number, 30); Serial.println(); Serial.print(F("Calling ")); Serial.println(number); if (!fona.callPhone(number)) { Serial.println(F("Failed")); } else { Serial.println(F("Sent!")); } break; } case 'A': { // get call status int8_t callstat = fona.getCallStatus(); switch (callstat) { case 0: Serial.println(F("Ready")); break; case 1: Serial.println(F("Could not get status")); break; case 3: Serial.println(F("Ringing (incoming)")); break; case 4: Serial.println(F("Ringing/in progress (outgoing)")); break; default: Serial.println(F("Unknown")); break; } break; } case 'h': { // hang up! if (! fona.hangUp()) {
break; } case 'p': { // pick up! if (! fona.pickUp()) { Serial.println(F("Failed")); } else { Serial.println(F("OK!")); } break; } /*** SMS ***/ case 'N': { // read the number of SMS's! int8_t smsnum = fona.getNumSMS(); if (smsnum < 0) { Serial.println(F("Could not read # SMS")); } else { Serial.print(smsnum); Serial.println(F(" SMS's on SIM card!")); } break; } case 'r': { // read an SMS flushSerial(); Serial.print(F("Read #")); uint8_t smsn = readnumber(); Serial.print(F("\n\rReading SMS #")); Serial.println(smsn); // Retrieve SMS sender address/phone number. if (! fona.getSMSSender(smsn, replybuffer, 250)) { Serial.println("Failed!"); break; } Serial.print(F("FROM: ")); Serial.println(replybuffer);
// Retrieve SMS value. uint16_t smslen; if (! fona.readSMS(smsn, replybuffer, 250, &smslen)) { // pass in buffer and max len! Serial.println("Failed!"); break; } Serial.print(F("***** SMS #")); Serial.print(smsn); Serial.print(" ("); Serial.print(smslen); Serial.println(F(") bytes *****")); Serial.println(replybuffer); Serial.println(F("*****")); break; } case 'R': { // read all SMS int8_t smsnum = fona.getNumSMS(); uint16_t smslen; int8_t smsn; if ( (type == FONA3G_A) || (type == FONA3G_E) ) { smsn = 0; // zero indexed smsnum--; } else { smsn = 1; // 1 indexed } for ( ; smsn <= smsnum; smsn++) { Serial.print(F("\n\rReading SMS #")); Serial.println(smsn); if (!fona.readSMS(smsn, replybuffer, 250, &smslen)) { // pass in buffer and max len! Serial.println(F("Failed!")); break; } // if the length is zero, its a special case where the index number is higher // so increase the max we'll look at! if (smslen == 0) { Serial.println(F("[empty slot]")); smsnum++; continue; }
Serial.print(F("***** SMS #")); Serial.print(smsn); Serial.print(" ("); Serial.print(smslen); Serial.println(F(") bytes *****")); Serial.println(replybuffer); Serial.println(F("*****")); } break; } case 'd': { // delete an SMS flushSerial(); Serial.print(F("Delete #")); uint8_t smsn = readnumber(); Serial.print(F("\n\rDeleting SMS #")); Serial.println(smsn); if (fona.deleteSMS(smsn)) { Serial.println(F("OK!")); } else { Serial.println(F("Couldn't delete")); } break; } case 's': { // send an SMS! char sendto[21], message[141]; flushSerial(); Serial.print(F("Send to #")); readline(sendto, 20); Serial.println(sendto); Serial.print(F("Type out one-line message (140 char): ")); readline(message, 140); Serial.println(message); if (!fona.sendSMS(sendto, message)) { Serial.println(F("Failed")); } else { Serial.println(F("Sent!")); } break;
} case 'u': { // send a USSD! char message[141]; flushSerial(); Serial.print(F("Type out one-line message (140 char): ")); readline(message, 140); Serial.println(message); uint16_t ussdlen; if (!fona.sendUSSD(message, replybuffer, 250, &ussdlen)) { // pass in buffer and max len! Serial.println(F("Failed")); } else { Serial.println(F("Sent!")); Serial.print(F("***** USSD Reply")); Serial.print(" ("); Serial.print(ussdlen); Serial.println(F(") bytes *****")); Serial.println(replybuffer); Serial.println(F("*****")); } } /*** Time ***/ case 'y': { // enable network time sync if (!fona.enableNetworkTimeSync(true)) Serial.println(F("Failed to enable")); break; } case 'Y': { // enable NTP time sync if (!fona.enableNTPTimeSync(true, F("pool.ntp.org"))) Serial.println(F("Failed to enable")); break; } case 't': { // read the time
char buffer[23]; fona.getTime(buffer, 23); // make sure replybuffer is at least 23 bytes! Serial.print(F("Time = ")); Serial.println(buffer); break; } /*********************************** GPS (SIM808 only) */ case 'o': { // turn GPS off if (!fona.enableGPS(false)) Serial.println(F("Failed to turn off")); break; } case 'O': { // turn GPS on if (!fona.enableGPS(true)) Serial.println(F("Failed to turn on")); break; } case 'x': { int8_t stat; // check GPS fix stat = fona.GPSstatus(); if (stat < 0) Serial.println(F("Failed to query")); if (stat == 0) Serial.println(F("GPS off")); if (stat == 1) Serial.println(F("No fix")); if (stat == 2) Serial.println(F("2D fix")); if (stat == 3) Serial.println(F("3D fix")); break; } case 'L': { // check for GPS location char gpsdata[120]; fona.getGPS(0, gpsdata, 120); if (type == FONA808_V1)
Serial.println(F("Reply in format: mode,longitude,latitude,altitude,utctime(yyyymmddHHMMSS),ttff,satellites,speed,course")); else Serial.println(F("Reply in format: mode,fixstatus,utctime(yyyymmddHHMMSS),latitude,longitude,altitude,speed,course,fixmode,reserved1,HDOP, PDOP,VDOP,reserved2,view_satellites,used_satellites,reserved3,C/N0max,HPA,VPA")); Serial.println(gpsdata); break; } case 'E': { flushSerial(); if (type == FONA808_V1) { Serial.print(F("GPS NMEA output sentences (0 = off, 34 = RMC+GGA, 255 = all)")); } else { Serial.print(F("On (1) or Off (0)? ")); } uint8_t nmeaout = readnumber(); // turn on NMEA output fona.enableGPSNMEA(nmeaout); break; } /*********************************** GPRS */ case 'g': { // turn GPRS off if (!fona.enableGPRS(false)) Serial.println(F("Failed to turn off")); break; } case 'G': { // turn GPRS on if (!fona.enableGPRS(true)) Serial.println(F("Failed to turn on")); break; }
case 'l': { // check for GSMLOC (requires GPRS) uint16_t returncode; if (!fona.getGSMLoc(&returncode, replybuffer, 250)) Serial.println(F("Failed!")); if (returncode == 0) { Serial.println(replybuffer); } else { Serial.print(F("Fail code #")); Serial.println(returncode); } break; } case 'w': { // read website URL uint16_t statuscode; int16_t length; char url[80]; flushSerial(); Serial.println(F("NOTE: in beta! Use small webpages to read!")); Serial.println(F("URL to read (e.g. www.adafruit.com/testwifi/index.html):")); Serial.print(F("http://")); readline(url, 79); Serial.println(url); Serial.println(F("****")); if (!fona.HTTP_GET_start(url, &statuscode, (uint16_t *)&length)){ Serial.println("Failed!"); break; } while (length > 0) { while (fona.available()) { char c = fona.read(); // Serial.write is too slow, we'll write directly to Serial register! #if defined(AVR_ATmega328P ) || defined( AVR_ATmega168) loop_until_bit_is_set(UCSR0A, UDRE0); /* Wait until data register empty. */ UDR0 = c; #else
#endif } Serial.write(c); length--; if (! length) break;
} Serial.println(F("\n****")); fona.HTTP_GET_end(); break; } case 'W': { // Post data to website uint16_t statuscode; int16_t length; char url[80]; char data[80]; flushSerial(); Serial.println(F("NOTE: in beta! Use simple websites to post!")); Serial.println(F("URL to post (e.g. httpbin.org/post):")); Serial.print(F("http://")); readline(url, 79); Serial.println(url); Serial.println(F("Data to post (e.g. \"foo\" or \"{\"simple\":\"json\"}\"):")); readline(data, 79); Serial.println(data); Serial.println(F("****")); if (!fona.HTTP_POST_start(url, F("text/plain"), (uint8_t *) data, strlen(data), &statuscode, (uint16_t *)&length)) { Serial.println("Failed!"); break; } while (length > 0) { while (fona.available()) { char c = fona.read(); #if defined( AVR_ATmega328P ) || defined( AVR_ATmega168 ) loop_until_bit_is_set(UCSR0A, UDRE0); /* Wait until data register empty. */ UDR0 = c;
length--; if (! length) break; } } Serial.println(F("\n****")); fona.HTTP_POST_end(); break; } /*****************************************/ case 'S': { Serial.println(F("Creating SERIAL TUBE")); while (1) { while (Serial.available()) { delay(1); fona.write(Serial.read()); } if (fona.available()) { Serial.write(fona.read()); } } break; } default: { Serial.println(F("Unknown command")); printMenu(); break; } } // flush input flushSerial(); while (fona.available()) { Serial.write(fona.read()); }
} void flushSerial() { while (Serial.available()) Serial.read(); } char readBlocking() { while (!Serial.available()); return Serial.read(); } uint16_t readnumber() { uint16_t x = 0; char c; while (! isdigit(c = readBlocking())) { //Serial.print(c); } Serial.print(c); x = c - '0'; while (isdigit(c = readBlocking())) { Serial.print(c); x *= 10; x += c - '0'; } return x; } uint8_t readline(char *buff, uint8_t maxbuff, uint16_t timeout) { uint16_t buffidx = 0; boolean timeoutvalid = true; if (timeout == 0) timeoutvalid = false; while (true) { if (buffidx > maxbuff) { //Serial.println(F("SPACE")); break; } while (Serial.available()) { char c = Serial.read();
//Serial.print(c, HEX); Serial.print("#"); Serial.println(c);
if (c == '\r') continue; if (c == 0xA) {
if (buffidx == 0) // the first 0x0A is ignored continue;
timeout = 0; // the second 0x0A is the end of the line timeoutvalid = true;
break;
}
buff[buffidx] = c; buffidx++;
}
if (timeoutvalid && timeout == 0) {
//Serial.println(F("TIMEOUT"));
break;
}
delay(1);
}
buff[buffidx] = 0; // null term return buffidx;
}
Precautions:
1. Double check the connections before powering on thecircuit.
2. Don’t use loose jumper cables.
3. Check whether proper board is selected from ArduinoIDE.
4. Ensure proper placement of sensor for correct working.
5. Don’t lose hope if Flex Sensor or LED does not runs properly for the first time, try again.
Conclusion:
You can successfully interface different devices using the Resistance principle of Flex Sensor.s