Mobile Intercom With A6 Module and Arduino

In this instructable I show you how I made a intercom using a GSM module.

If you press the big button, the programmed number is called. The call is ended after a programmed time, or by pressing the hangup button.

Components I used:

Button: https://www.aliexpress.com/item/A13-5PCS-LOT-Black...

Arduino pro mini: https://www.aliexpress.com/store/product/Pro-Mini-...

A6 module: https://www.aliexpress.com/item/mini-A6-GPRS-GSM-K...

Speaker: https://www.aliexpress.com/item/5PCS-Lot-New-8-ohm...

Microphone: https://www.aliexpress.com/item/High-Quality-1Pc-L...

Tactile switch, any, like: https://www.aliexpress.com/item/CNIM-Hot-100-Pcs-6...

Edit: see my other instructable for an improved version.

The get sound of the phone call, i needed to tweak the connections of the module on the PCB. On the PCB, the EAR_L and EAR_R are connected to the pins, but I needed the REC- and REC+ connections.

So, I cut the wiring on the PCB and made connections directly from the REC- and REC+ connectors of the module to the pins which previously had the EAR connections

Attached is the program I used, my program was inspired by Saravanan AL:

Pin 6 and 7 are both pulled up to 5V.

If the button connected to pin 7 is pressed, the programmed number is called

If the button connected to pin 6 is pressed, the "ATH" command hangs up.

Edit: the SoftwareSerial is able to send at 115200, but not able to receive well at 115200 BAUD.

Connect all components to a standard PCB (30 x 70 mm).

The Arduino pro mini also gets a switch to the reset (RST, pulled up by 10k to VCC) pin, to reset the Arduino.

In 123D design a designed a box for the intercom. See attached STL files.

The files were printed on a Wanhao Duplicator i3 in Wanhao silver PLA. The box was printed with a 0.8 mm nozzle, the top with a 0.6 nozzle.

Finally screw all together and glue in the tactile buttons. The speaker is glued to the top of the box.

Connect to a 5V phone charger as power supply and you are finished!