I have a problem with PIR sensor and GSM module SIM900 while receiving SMS
if I send a SMS to SIM900, PIR signal output goes HIGH and system recognize this as a motion detected.
it seems that problem is when SIM900 starting communication to Arduino Nano (also tested Arduino ATMEGA 2560, hardware usart1 or softwareSerial) signal pin on PIR sensor goes HIGH no matter if it is connected to arduino.
simplest test which I've tried was,
1.Enabled communication Initial communication (on arduino hardware USART and USART1 OR USART and softwareSerial on atmega 2560 , USART and softwareSerial on NANO ))
2. turn on SIM 900
3. rx tx (and gnd) from SIM900 connected to arduino
4. PIR signal pin connected only to oscilloscope.
5. in loop I have only reading serial function
if I send sms to sim900 I can see on osciloscope signal pir pin goes HIGH.
SIM900 is connected to battery turnigy 3s 11,1V 5200mAh so it is capable to power SIM900
Arduino and pir sensor is connected to USB
similar topic was not resolved in 2017
SIM900 will jam the other sensor when receiving a sms
I've also simple code with motion detection provided below
nanoPirGsm.ino (1.99 KB)