Interfacing with computer serial port and Python via pySerial module.
The wiring is so trivial. Start from data sheet we need 4 pins: GND, VCC, TX, RX.
Sensor operating voltage is from 2.5V to 5.5V and the current is about 2mA, then we can get power from serial port DTR or RTS pins. Look at this explanation. ATTENTION! RS-232 specification says that tension can be 25V. You can simply BURN the sonar, computer, house and more… Don’t do anything if you don’t know what are you doing.
In my case I am using USB to RS-232 converter. Output voltage is 5V so I don’t need additional circuitry, just simple pin to pin wiring.
And now little coding…
# Import pySerial module from serial import * # Open serial port and setup ser = Serial("COM10", baudrate=9600, bytesize=8, parity='N', stopbits=1, timeout=1) # Power up MaxSonar via DTR pin ser.setDTR(True) # Infinite loop while (True): # Read serial data data = ser.read(5) # Check data length if len(data) == 5: # Check data packet if data == "R" and data[1:4].isdigit(): # Convert to cm and print print int(data[1:4]) * 2.54, "cm" # Request next measurement ser.write(0) # Close ser.close()
Many thanks to Antonio Bugnone for soldering.