WEEK 9

Date: 28/11/2016 - 2/12/2016
Title: Interface Arduino and SIM800L

In this week, we have gone to Jalan Pasar to buy a GSM Module SIM800L. The price is only RM47.00. We would like to explain  about this module.

GSM SIM800L that we buy.

A SIM800L have a 12 pin.The pin is Antena, VCC, RESET, RX, TX, GND, Ring, DTR, Mic+, Mic-, Speaker+ and Speaker-. But we just use 5 pin only. Which is VCC, RX, TX, Antena and GND.

To can see the datasheet, click at the link above.

 http://wiki.seeedstudio.com/images/4/46/SIM800L_Hardware_Design_V1.00.pdf

The connection between Arduino Uno and SIM800l that we make:

For above module Arduino to SIM800L connectivity was pretty straight forward .

• SIM800 VCC ↔ Arduino 5v
• SIM800 GND (either one) ↔ Arduino GND
• SIM800 TXD ↔ Arduino D2 
• SIM800 RXD ↔ Arduino D3 

Caution! : SIM800 module itself uses input voltage of 3.7V – 4.2V. Therefore, if you directly connect the Vcc pin to Arduino 5V pin, it might damage the module as well. I tried 3.3V Arduino pin with no luck. So I tried to connect the Vcc pin to 5V pin from the Arduino, my module is damage. The module not responding anything after that. 

The solution for this problem, by using  LM2596 DC-DC buck converter step-down power module. You can connected 5V from Arduino to pin IN+, step down the voltage (adjust between the range 3.7V-4.2V )and  connect to Vcc SIM800L with the pin OUT+.

LM2596 DC-DC Converter Step down