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:
Arduino pro mini: https://www.aliexpress.com/store/product/Pro-Mini-...
Tactile switch, any, like: https://www.aliexpress.com/item/CNIM-Hot-100-Pcs-6...
Edit: see my other instructable for an improved version.
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Step 1: Tweak the A6 Module
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
Step 2: Program the Arduino Pro Mini
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.
Step 3: Connect All to a PCB
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.
Step 4: Design and Print a Box
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.
Step 5: Add All Together
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!