[PYTHON] Operate an oscilloscope with a Raspberry Pi

1.First of all

Connect the tactile switch to GPIO of Raspberry Pi, and when the switch is pressed, ": RUN" ": STOP" of [SCPI command](https://www.google.co.jp/search?hl=ja&as_q=SCPI command) Is sent to the oscilloscope. Use pyVISA to send SCPI commands.

2. Wiring

|BCM|Physical|I/O|function |---+--------+---+---- | 2 |3 |IN |RUN command(:RUN)Issue | 3 |5 |IN |STOP command(:STOP)Issue |17 |11 |OUT|LED lighting

The LEDs are connected via a 3kΩ current limiting resistor.

3. Program

--Please install pyUSB, pyVISA, pyVISA-py on Raspberry Pi with pip command in advance. --The VISA address is hard-coded (see the appendix for how to find the VISA address) --Run with sudo python scpi-commander.py (sudo important!)

scpi-commander.py

import RPi.GPIO as GPIO
import time
import visa


PORT_RUN  =  2
PORT_STOP =  3
PORT_LED  = 17
VISA_ADDR = "USB0::6833::1230::DS1Zxxxxxxxxxx::0::INSTR"


GPIO.setmode(GPIO.BCM)
GPIO.setup(PORT_LED, GPIO.OUT)
GPIO.setup(PORT_RUN, GPIO.IN)
GPIO.setup(PORT_STOP,GPIO.IN)


def open_dso():
    rm = visa.ResourceManager()
    resources = rm.list_resources()
    #print(resources)
    try:
        dso = rm.open_resource(VISA_ADDR)
    except:
        print("Not Found:", resources)
    else:
        pass
        #print("Detected")

    return dso


def main():
    try:
        dso = open_dso()
    except:
        print("DSO Open Failed, exit.")
        exit(1)
    else:
        print("DSO Open Success.")

    try:
        while True:
            port_run  = GPIO.input(PORT_RUN)
            port_stop = GPIO.input(PORT_STOP)

            if port_run == GPIO.LOW:
                GPIO.output(PORT_LED,GPIO.HIGH)
                #print(dso.query("*IDN?"))
                print(":RUN")
                dso.write(":RUN")
                while(GPIO.input(PORT_RUN)==GPIO.LOW):
                    #print("pressing...")
                    time.sleep(0.1)
            
            if port_stop == GPIO.LOW:
                GPIO.output(PORT_LED,GPIO.HIGH)
                print(":STOP")
                dso.write(":STOP")
                while(GPIO.input(PORT_STOP)==GPIO.LOW):
                    #print("pressing...")
                    time.sleep(0.1)

            GPIO.output(PORT_LED,GPIO.LOW)
            time.sleep(0.1)

    except KeyboardInterrupt:
        GPIO.cleanup()


main()

4. Conclusion

――If you use the foot switch, you can operate it with your feet even if both hands are occupied.

5. Reference materials

This is an article that I used as a reference when creating this article.

-Use GPIO of Raspberry Pi from Python

X. Appendix How to find the VISA address

Connect the oscilloscope and Raspberry Pi (or PC) in advance via USB.

> sudo python
>>> import visa
>>> rm = visa.ResourceManager()
>>> print(rm.list_resources())
('USB0::0x1AB1::0x04CE::DS1Zxxxxxxxxxx::0::INSTR')