Detect Signal using GRC and Raspberry pi


I am trying to simply detect specific signal at specific frequency (as a start) then send signal from raspberry pi to arduino to trigger other command.

From my research I found GRC as best option with hackRF one. I got the signal at monitor as below but as I am totally new in GRC I don’t know which blocks can detect the signal, I think the best way is to record the signal in file then detecting it in future using kind of comparison or by measuring the power.

Please help me to choose appropriate blocks to achieve this result.

The signal to be detected

Install the rpi_gpio gem directly to the pi as well as the arduino_firmata gem.

With these gems you can manipulate the pi’s gpio pins as well as directly control the Arduino.

On the Arduino make sure you load the firmata sketch. This will open the arduino’s serial to the pi and you can control and catch the io stream

The code for the firmata. I make a global variable called pin for my short hand… But you can name it anything. I do recommend making it global however.

require ‘arduino_firmata’
$pin = ArduinoFirmata.connect # this binds a global variable to connect and communicate with the Arduino.

def firmata_ver
puts "Firmata version: #{$pin.version}

making a method will keep you from having to retype the puts string for the firmata version.

#simple on/off commands for io pins.

def led_on
a = proc[ $pin.digital_write 5, true]
#the code method_name(this case $pin).digital_write pin_number, true/false tells the pi to connect with the Arduino and access the io pin and turn it on or off. I used 5 in this example. Setting it to true will turn the pin on.

def led_off
a = proc[ $pin.digital_write 5, false]

digital_write makes the pin a output pin. The next attr_accessor I will show you is digital_read. This pulls information about a pin. Let’s make a new method for a new led.

def blue_led_on
a = proc[ $ write 6, true]
b = proc[puts “blue led is #{$pin.digital_read 6}”)

#input pins. These can be trigger pins like buttons. Where output pins sends voltage out, input pins act like a ground pin. It takes the voltage in and uses It for data measurements.

Connect your button to the 3.5v aux of the Arduino. NOT THE 5V PIN! IO pins can only take 3.5 volts and cannot exceed 30ma(milliamps). If it draws more than a led, don’t use the io pins to power it. These are our signal pins.

3.5v pin to button, button to pin #(we will use 7)

button = $pin.pin_mode 7, ArduinoFirmata::INPUT ;
While button == true
if led_off == true
puts. $pin.digital_read 7
puts $pin.digital_read 7
If led_on == true
puts $pin.digital_read 7
puts $ read 7

#pwm (pulse width modulation). Makes a output pin produce a square wave.

This is used to control fan speeds, motors, servos, etc.