SIM800L Module Bringup

Check the SIM800L module working condition:
Specification: SIM800L Hardware spec
GSM Standard: GSM Standard - ETSI TS 127 007 - AT Commands
Courtesy: https://nettigo.eu/products/sim800l-gsm-grps-module

Mini GSM/GPRS module

SIM800L is a miniature cellular module which allows for GPRS transmission, sending and receiving SMS and making and receiving voice calls. Low cost and small footprint and quad band frequency support make this module perfect solution for any project that require long range connectivity. After connecting power module boots up, searches for cellular network and login automatically. On board LED displays connection state (no network coverage - fast blinking, logged in - slow blinking).

NOTICE: Be prepared to handle huge power consumption with peek up to 2A. Maximum voltage on UART in this module is 2.8V. Higher voltage will kill the module.

Two antennas!

This module have two antennas included. First is made of wire (which solders directly to NET pin on PCB) - very useful in narrow places. Second - PCB antenna - with double sided tape and attached pigtail cable with IPX connector. This one have better performance and allows to put your module inside a metal case - as long the antenna is outside.

Specification

• Supply voltage: 3.8V - 4.2V
• Recommended supply voltage: 4V
• Power consumption:
  • sleep mode < 2.0mA
  • idle mode < 7.0mA
  • GSM transmission (avg): 350 mA
  • GSM transmission (peek): 2000mA
• Module size: 25 x 23cm
• Interface: UART (max. 2.8V) and AT commands
• SIM card socket: microSIM (bottom side)
• Supported frequencies: Quad Band (850 / 950 / 1800 /1900 MHz)
• Antenna connector: IPX
• Status signaling: LED
• Working temperature range: -40 do + 85 ° C

Set includes:

• SIM800L module
• goldpin headers
• wire antenna
• PCB antenna with pigtail and IPX connector

Module pinout

Pinout (bottom side - left):

• RING (not marked on PBC, first from top, square) - LOW state while receiving call
• DTR - sleep mode. Default in HIGH state (module in sleep mode, serial communication disabled). After setting it in LOW the module will wake up.
• MICP, MICN - microphone (P + / N -)
• SPKP, SPKN - speaker (P + / N -)

Pinout (bottom side - right):

• NET - antenna
• VCC - supply voltage
• RESET - reset
• RXD - serial communication
• TXD - serial communication
• GND - ground

Moreinfo : https://github.com/stephaneAG/SIM800L/blob/master/README.md 

Sanity Test Connection: 

1.  Flash Arduino with empty code to connect SIM800L to laptop(Ardiuno act as USB to TTL converter) 

void setup() {

  // put your setup code here, to run once:

}

void loop() {

  // put your main code here, to run repeatedly:

}

3. Connect Arduino 3.3 V to VCC supply 800L and remove the SIM card ()

3. Connect GND to Arduino GND

4. Connect RX to Arduino RX0

5. Connect TX to Arduino TX0

6. Open Serial Monitor and choose 9600 or any 115200 baud rate, CR and LF, since 800L is supports auto baud rate

Courtesy: https://github.com/stephaneAG/SIM800L/blob/master/README.md

init the auto-bauder: AT
OK

get module name & version:ATI
SIM800 R14.18

turn on verbose errors:ATI+CMEE=2
SIM800 R14.18

get SIM card number:AT+CCID

get IMEI card number:AT+CGSN

to list available networks: AT+COPS=?

check that we're connected to a network:AT+COPS?
+COPS: 0

check signal strength:AT+CSQ
+CSQ: 26,0

check battery state:AT+CBC =?

+CBC: (0-2),(1-100),(voltage)
: Charge status
    0 ME is not charging
    1 ME is charging
    2 Charging has finished
: Battery connection level
    1...100 battery has 1-100 percent of capacity remaining

: Battery voltage(mV)
     0000 - 4700

check battery state:AT+CBC   (while i connected to 3.3v of Ardunio)

+CBC: 0,0,3286

pages: AT+CSCS=?

+CME ERROR: SIM not inserted

Observation: After inserting valid SIM CARD
check signal strength:AT+CSQ

+CSQ: 29,0
Syntax:  Response +CSQ: ,
  0 -115 dBm or less,
                 1 -111 dBm, 
                 2...30  -110...-54 dBm
                 31 -52 dBm or greater 
                 99 not known or not detectable 
(in %): 0...7 As RXQUAL values in the table in GSM 05.08 [20] subclause 7.2.4 
                 99 Not known or not detectable

Powering Method #1:

Voltage divider :(led is not blinked at all and tx in Ardiuno keep flashing faster)

+5v ------(5 ohm ) R1 ------- (10* 2 ohm) R2-------->GND

                    |

                    +--------> VCC [SIM800L ]  the voltage divider not working 

GND -------------------------> GND [Module  ]

Measured Current flow 180mA through resisters. Voltage across R2 is 4.1V and Heat dissipated in resisters. R1 (2*10 ohm connected parallel) and R2( 2* 10 ohm resister series). 

I have tried replacing all 10 Ohm with 1K, but no use. Amps measure 1.2 mA only.

Summary: This method not worked
Why voltage divider doesn't work, since the resistor, since the resistors are 1/4 watt and its not good use high watt resistors , hence voltage regulator is suggested in that high amp power supply. Kindly refer hardware design doc of SIM800L.

Powering Method #2:

5V through 20 ohm worked:

+5V -------R1----R2-------->VCC [SIM800L ]

GND ----------------------->GND [module  ]
R1 - 10 ohm
R2 - 10 ohm

Note: Even 3*10 ohms not worked, TX of Ardiuno has n impact 

Observation #1:

check battery state:AT+CBC   (while i connected to Vcc to 5.4V USB adapter(nubia 1A)  and 2*10 Ohms and measured initially 55mA, 12mA and 30mA and later LED blink per secs finally ~12mA. But if execute AT+COPS=? list network it raises till 75mA and later TX of Arduino keeps blinking.

+CBC: 0,100,5108
Syntax: Response +CBC: , ,

   bcs = 0 - Not charging, 1-charging, 2- finished

   bcl = 1-100 % of battery level

   Volt = mV

to list available networks: AT+COPS=? 

Sample: 

AT+COPS=?
+COPS: (2,"vodafone","voda UK","23415"),(3,"T-Mobile","TMO UK","23430"),(3,"O2","O2 -UK","23410"),,(0-4),(0-2)

OK

AT+COPS?
+COPS: 1

OK

summary:

If I try to get COPS=?(avil netwrk list), the Arduino Tx light keeps blinking ... seems voltage levels mismatch occurred b/w 800L and Ad's TX as occurred in voltage divider circuit, becoz searching network might draw more current.

You need more supply if u need to connect SIM and try ...( http://wiki.groundlab.cc/doku.php?id=microcontrollersgsm - not useful)

Tried by removing one 10 ohm resister from Powering Method #2:

list available networks: AT+COPS=? 

+COPS: (1,"AIRCEL","AIRCEL","40442"),(1,"BPL USWEST (Tamil Nadu)","BPL MO","40443"),(1,"405044","405044","405044"),(2,"AirTel","AirTel","40494"),(1,"405852","405852","405852"),(1,"Tamil Nadu","CellOne","40480"),,(0-4),(0-2)

OK

check battery state:AT+CBC  (while i connected to Vcc to 5.4V USB adapter(nubia 1A)  and 10 Ohms and measured initially ~65mA, 14mA and 35mA and later LED blink per secs. And ~14mA. But if execute AT+COPS=? list network it raises till 85 mA max and later TX of Arduino blinks once for response.

+CBC: 0,100,5223


OK

AT+GSV

SIMCOM_Ltd
SIMCOM_SIM800L
Revision:1418B04SIM800L24


OK

AT+CSMINS?   #is sim instered ? : 

+CSMINS: 0,0

OK

AT+CSMINS=?

+CSMINS: (0,1)

OK

AT+CSMINS=1

OK

AT+CSMINS?

+CSMINS: 1,0

OK

AT+COPN

ERROR

AT+CMEE?

+CMEE: 0

OK

AT+CMEE=1

OK

AT+COPN

+CME ERROR: 10

at+cops

+CME ERROR: 100

AT+CMEE=2

OK

at+cops

+CME ERROR: unknown

at+cops?

+COPS: 0

OK

at+copn?

+CME ERROR: SIM not inserted

You can change the baud rate to 9600 on the SIM800L with the command:AT+IPR=9600
Then to save this (to last between boot cycles), give the commandAT&W
To see the saved settings, give the command:AT&V

Powering Method #3:

LM 317T:  input source 12V 1Amps to LM317 but it seems board needs 2 Amps. LM can deliver 1Amps

Powered OFF the board and inserted the CARD, After inserting SIM Card , the output voltage dropped to less than 3.3v hence the board not functional and keeps restarting ..... :-( 

RDY

+CFUN: 1

+CPIN: READY

AT+CBC

+CBC: 0,39,3714

OK

Call Ready

SMS Ready

AT+CBC

+CBC: 0,39,3719

OK

Call Ready

SMS Ready

AT+CBC

+CBC: 0,13,3511

OK

AT+CBC

+CBC: 0,0,0

Powering Method #4:

As suggested in SIM800L hardware design I choose 

And its available in market as module ... U can buy Buck Converters .. Going to try ......