Week 9, Input Devices

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Assignment

Group assigment

• Probe an input device(s)’s analog levels and digital signals
• Document your work on the group work page and reflect on your individual page what you learned

Individual assignment

• Measure something: add a sensor to a microcontroller board that you have designed and read it.

Checklist

from Nueval

• Linked to the group assignment page
• Documented what you learned from the interfacing an input device to your microcontroller
• Documented your design and fabrication process
• Explain the programming processes you used
• Included original design files and source code
• Included a ‘hero shot’ of your board

Individual work

Making board

Design files

Programming ESP32

pip install esptool
brew install thonny

#
# step_response.py
#
# ESP32S3 XIAO touch
# Albert Vernon Smith 3/25/25
#
# Based on hello.touch.S3.py
# https://academy.cba.mit.edu/classes/input_devices/step/ESP32S3/hello.touch.S3.py
# From Neil Gershenfeld 7/25/24
#
# This work may be reproduced, modified, distributed,
# performed, and displayed for any purpose, but must
# acknowledge this project. Copyright is retained and
# must be preserved. The work is provided as is; no
# warranty is provided, and users accept all liability.
#
# install MicroPython
#    https://micropython.org/download/RPI_PICO/
#

import time
import machine

eps = 0.01 # smoothing filter fraction
loop = 500 # smoothing filter iterations

# The original code had hard coded pins
# Use a class which allow for flexibility

class Pad:
    # Initialize the pad, largely by specifying the pin
    # Also track the distance between the pad and ground
    # Also track the size of the page 
    def __init__(self, pin, dist = 1, length = 20, height = 5):
        self.pin = machine.Pin(pin)
        self.dist = dist
        self.area = length * height
        self.rmin = 1e6
        self.rfilt = 0
        self.t = machine.TouchPad(self.pin)

    def getRmin(self):
        return self.rmin

    def getRfilt(self):
        return self.rfilt

    def setRmin(self, num):
        self.rmin = num

    def setRfilt(self, num):
        self.rfilt = num

    def updateRfilt(self):
        r = self.t.read()
        rmin = self.getRmin()
        if (r < rmin):
            rmin = r
            self.setRmin(rmin)
        rfilt = self.getRfilt()
        rfilt = (1-eps)*rfilt+eps*(r-rmin)
        self.setRfilt(rfilt)


sizepins = [1,3,5,6,4]
pins = sizepins

#distpins = [8,7,9,2]
#pins = distpins

pads = []

for p in pins:
    pads.append(Pad(p))

while True:
    for i in range(loop):
        for pad in pads:
            pad.updateRfilt()

    rfilts = [str(p.getRfilt()) for p in pads]
    print(",".join(rfilts))

Programming SAMD21