Transform a RPICT into a web scope

Overview

This is to show the waveform on a web browser using the RPICT in a special configuration. We will use the Raspberrypi to collect the analog data from the RPICT and serve them as a HTTP server.

IMPORTANT. This is not a substitute for a scope. This is just a playground for demonstration.

Preliminaries

Make sure you have a fresh Raspbian image installed.

Setup the Raspbian to enable the serial port. See the guide below to complete this.
Howto setup Raspbian for serial read

Upload the Sketch

The RPICT will require a different sketch depending on the model. Download the appropriate sketch that applies.

RPICT4T4 RPICT3V1

RPICT Scope Attiny Version 1.0

RPICT3T1

coming soon.

RPICT7V1 RPICT4V3 RPICT8

Prepare the Raspberrypi for uploading new firmwares. Follow the instructions in the guide below.

Upload Arduino sketch from Raspberrypi to RPICT

Get the scope sketch.

wget lechacal.com/RPICT/sketch/RPICT_SCOPE_MCP3208_v1_4.ino.hex

Upload it to the RPICT unit.

lcl-upload-sketch.sh RPICT_SCOPE_MCP3208_v1_4.ino.hex

Read The data

On the web browser

Setup the web server

Navigate to the http public folder and install the scope webserver.

cd /var/www/html/
sudo wget lechacal.com/RPICT/scope/rpict-scope-v2.0.zip
sudo unzip rpict-scope-v2.0.zip

This will create a folder called scope. There is a configuration file inside called rpict-scope.conf which should not need modification.

Now start a server instance

cd /var/www/html/
python3 -m http.server 8000

Run the service and view the data

From the raspberrypi run the command below. You might have to open a second terminal window for this.

sudo /var/www/html/scope/lcl-rpict-scope.py

Then now open a web browser and go to address

http://raspberrypi:8000/scope/scope.html?yrange=4100

In the above address change 'raspberrypi' accordingly to your raspberrypi hostname or ip address.

Modify yrange in the address as required.

Get the data from serial port

You can read the data directly with the lcl-run command.

lcl-run

The out put format is N:d0,d1,d2,d3....dn

Where N is the channel number. d0 d1 d2 dn are the raw data points.

A simple python script to read the data would look like this below:

#!/usr/bin/python3
import serial
ser = serial.Serial('/dev/ttyAMA0', 38400)
 
try:
       while 1:
                # Read one line from the serial buffer
                try:
                    line = ser.readline().decode().strip()

                    # Create an array of the data
                    z = line.split(':')
                    if len(z)>0:
                        channel = z[0]
                        data = z[1].split(',')
               
                        print(channel)
                        print(data)
                except UnicodeDecodeError:
                    pass

except KeyboardInterrupt:
       ser.close()

This above can be run directly with

sudo /var/www/html/scope/demo.py