CSV output of pulse data with Raspberry Pi (confirm analog input with python)

Procedures and links

1. Preparation and basics http://qiita.com/tkyko13/items/62ff91bce7d9e555c434
2. Analog input confirmation http://qiita.com/tkyko13/items/981989a006a95821ccde
3. Check with python here
4. Pulse sensor http://qiita.com/tkyko13/items/e4afc73add81d7bbb426
5. csv output http://qiita.com/tkyko13/items/9c0eb46c1b65129d2556

environment

A note on how to write python code on a Raspberry Pi ・ Created with IDLE on the desktop of Raspberry Pi (Requires display and keyboard) ・ Vi command with Raspberry Pi (Requires display and keyboard, no mouse required) ・ Created with Remote Desktop and IDLE on Raspberry Pi (You need a way to check the Raspberry Pi's internet connection and IP) ・ Vi from ssh connection to Raspberry Pi (If you can confirm the internet connection and IP) ・ Send python file to Raspberry Pi by ftp (If you can confirm the internet connection and IP Also, you can write in the development environment of your own PC, sublime text, etc.)

I use it flexibly Basically remote connection There is an "arp -a" command from within the same network as a means to check the IP. I don't use mac ftp software so much, but I don't think it's good. At the time of win, winscp + putty was very nice, and I also liked teraterm. I like the terminal

Sample code part 1

I'll put one of the simplest chords for now I am using the I2C address from the previous "Analog Input Confirmation" First of all, I see the value every time I execute it

sample1.py

import smbus

I2C_ADDRESS = 0x48
bus = smbus.SMBus(1)

bus.write_byte(I2C_ADDRESS, 0xFF)
value=bus.read_byte(I2C_ADDRESS)
print value

Sample code part 2

Make it always visible in repetitive statements

sample2.py

import smbus
import time

I2C_ADDRESS = 0x48

bus = smbus.SMBus(1)

while True:
  bus.write_byte(I2C_ADDRESS, 0xFF)
  value=bus.read_byte(I2C_ADDRESS)
  print value
  time.sleep(0.1)

Sample code part 3

Since the purpose is to finally take the pulse, we will use threads to process every millisecond.

sample3.py

import threading
import smbus
import time

I2C_ADDRESS = 0x48

bus = smbus.SMBus(1)

def loop():
	bus.write_byte(I2C_ADDRESS, 0xFF)
	value=bus.read_byte(I2C_ADDRESS)
	print value
	t=threading.Timer(0.1, loop)
	t.start()

t=threading.Thread(target=loop)
t.start()

Sample code 4 (additional note)

This time, I want to measure only 10 seconds and end it, so I will write a process that ends when the thread is executed 100 times. The value given to the argument of the thread is increased steadily. I thought of a simpler way, but I couldn't think of it. If you know anything, please comment. (Since the file operation will be performed later, it is necessary to close the file at the end of the process, so I added it.)

sample4.py

import smbus
import time
import threading
import csv

I2C_ADDRESS = 0x48

bus = smbus.SMBus(1)
f = open('data.csv', 'w')

def loop(count):

    # count = count+1
    bus.write_byte(I2C_ADDRESS, 0xFF)
    value = bus.read_byte(I2C_ADDRESS)
    print value

    writer = csv.writer(f, lineterminator='\n')
    writer.writerow([value])

    if count < 100 :
        t = threading.Timer(0.1, loop, [count])
        t.start()
    else :
        f.close()
        print 'finish'

t = threading.Thread(target=loop, args=(0,))
t.start()

Next time I will use the last sample code