Step 1: Setting Up Our Raspberry Pi Hardware

First, connect our touch sensor to GPIO pins on our Raspberry Pi. Use some flexible cables

Identify 3 pins on our sensor:

GND - connect to ground pin
VCC - connct to 5V pin
SIG - connect to a signel pin

We'll use the 5V, ground and GPIO 18 on our raspberry pi in this example.

Step 2: Setting Up Our Environment on the Raspberry Pi

Obtain the IP address of our raspberry Pi.

Then connect to our raspberry pi using ssh:

ssh username@ipaddress

then type in our password.

Once we are in, then install apache2 as our webserver by typing in:

sudo apt-get install apache2

Step 3: Design a Piece of Python Code to Read Input From Our Sensor

Design

In our example code, we use a couple of different commands.

To indicate that we're happy, we do 2 long presses.

To indicate that we're sad, we do one short tap, and one long press.

To indicate that we're confused, we do one short tap, wait a beat, then 2 short taps. To indicate that we're happy, we do one short tap, one short gap, and one long press.

To indicate that we're bored, we 3 short taps.

Translating these to string commands:(t for short tap, T for long press, g for short gap, G for long gap)

happy: TgT

sad: tgT

confused: tGtgt

bored: tgtgt

Then we'll have our code output our current mood into a browser-friendly html file for serving.

Code

import RPi.GPIO as GPIO
import time

GPIO.cleanup()
GPIO.setmode(GPIO.BCM)
GPIO.setup(18,GPIO.IN)

touch_count = 0
touch_state = 0
touch_duration = 0
gap_duration = 0
current_cmd = ""

def cmd():
	global current_cmd
	if current_cmd[-3:] == "TgT":
		current_cmd = ""
		mood("Sad")
	if current_cmd[-3:] == "tgT":
		current_cmd = ""
		mood("Happy")
	if current_cmd[-5:] == "tGtgt":
		current_cmd = ""
		mood("Confused")
	if current_cmd[-5:] == "tgtgt":
		current_cmd = ""
		mood("Bored")

def mood(mood):
	file = open("index.html","w")
	html = """

Portable Mood Reporter

Hey, my most recent mood is

{}

"""
	file.write(html.format(mood))

while(1):
	time.sleep(0.001)
	if(GPIO.input(18)):
		if touch_state==0:
			if gap_duration > 2000:
				gap_duration = 0
			if gap_duration > 200:
				current_cmd = current_cmd + "G"
			else:
				current_cmd = current_cmd + "g"
			gap_duration = 0
			touch_state = 1
			touch_count = touch_count + 1
		if touch_state==1:
			touch_duration = touch_duration + 1
	else:
		if gap_duration < 10000:
			gap_duration = gap_duration + 1
		if touch_state==1:
			touch_state = 0
			if touch_duration > 200:
				current_cmd = current_cmd + "T"
			else:
				current_cmd = current_cmd + "t"
			touch_duration = 0
	cmd()