[电子技术]温度收集

一个有点物联网感觉的作品。原理是使用温度传感器（模拟输出）得到当前温度，网络上传，网络显示。
因为是模拟输出，raspberry pi不能直接使用。简单起见，直接用Arudino作为ADC，和raspberry pi串口通信。
网络上传是raspberry pi的强项。再加上我给raspberry pi装了无线USB网卡，更加方便，直接电源输入即可。
网络显示依赖于网络上传，本次使用的是yeelink的服务。提供类似温度记录的功能。直接拿来使用了。

温度收集部分，为了调试，增加了LCD用于显示当前温度。

raspberry pi部分。使用绿灯表示上传成功，红灯表示上传失败。实际运行没一次失败……
串口通信其实很简单，把USB相连即可。通讯上采用raspberry pi发一次请求，Arduino回应一次的被动方式。

raspberry pi的代码

import serial
import RPi.GPIO as GPIO
import datetime
from time import sleep
import httplib

PIN_LED_PASSED=22
PIN_LED_FAILED=23

API_KEY=’API_KEY_HERE’
HOST=’api.yeelink.net’
URI=’/v1.0/device/15530/sensor/26740/datapoints’

def loop(s):
    s.writelines([‘G’]) # send serial command to get current temperature
    c = s.readline().strip()
    if not c:
        return
    now = datetime.datetime.now().isoformat()
    print ‘[INFO]’, now, c
    if send_sensor_data(now, c):
        GPIO.output(PIN_LED_PASSED, GPIO.HIGH)
    else:
        GPIO.output(PIN_LED_FAILED, GPIO.HIGH)
    sleep(1)
    GPIO.output(PIN_LED_PASSED, GPIO.LOW)
    GPIO.output(PIN_LED_FAILED, GPIO.LOW)
    sleep(10) # sleep 10 seconds for yeelink limit(> 10s after previous request)

def send_sensor_data(timestamp, value):
    payload = ‘{“timestamp”:”‘ + timestamp + ‘”,”value”:’ + value + ‘}’
    headers = {‘U-ApiKey’: API_KEY}

    conn = httplib.HTTPConnection(HOST)
    conn.request(‘POST’, URI, payload, headers)
    resp = conn.getresponse()
    conn.close()
    if resp.status == 200:
        return True
    else:
        print ‘[WARN] failed to send sensor data,’, resp.reason
        return False

if __name__ == ‘__main__’:
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(PIN_LED_PASSED, GPIO.OUT)
    GPIO.setup(PIN_LED_FAILED, GPIO.OUT)

    s = serial.Serial(‘/dev/ttyACM0’, 9600, timeout = 1)
    s.open()
    print ‘[INFO] sensor data collector start’
    try:
        while True:
            loop(s)
    except KeyboardInterrupt:
        s.close()
        GPIO.cleanup()

import serial

import RPi.GPIO as GPIO

import datetime

from time import sleep

import httplib

PIN_LED_PASSED=22

PIN_LED_FAILED=23

API_KEY=‘API_KEY_HERE’

HOST=‘api.yeelink.net’

URI=‘/v1.0/device/15530/sensor/26740/datapoints’

def loop(s):

s.writelines([‘G’]) # send serial command to get current temperature

c = s.readline().strip()

if not c:

return

now = datetime.datetime.now().isoformat()

print ‘[INFO]’, now, c

if send_sensor_data(now, c):

GPIO.output(PIN_LED_PASSED, GPIO.HIGH)

else:

GPIO.output(PIN_LED_FAILED, GPIO.HIGH)

sleep(1)

GPIO.output(PIN_LED_PASSED, GPIO.LOW)

GPIO.output(PIN_LED_FAILED, GPIO.LOW)

sleep(10) # sleep 10 seconds for yeelink limit(> 10s after previous request)

def send_sensor_data(timestamp, value):

payload = ‘{“timestamp”:”‘ + timestamp + ‘”,”value”:’ + value + ‘}’

headers = {‘U-ApiKey’: API_KEY}

conn = httplib.HTTPConnection(HOST)

conn.request(‘POST’, URI, payload, headers)

resp = conn.getresponse()

conn.close()

if resp.status == 200:

return True

else:

print ‘[WARN] failed to send sensor data,’, resp.reason

return False

if __name__ == ‘__main__’:

GPIO.setmode(GPIO.BCM)

GPIO.setup(PIN_LED_PASSED, GPIO.OUT)

GPIO.setup(PIN_LED_FAILED, GPIO.OUT)

s = serial.Serial(‘/dev/ttyACM0’, 9600, timeout = 1)

s.open()

print ‘[INFO] sensor data collector start’

try:

while True:

loop(s)

except KeyboardInterrupt:

s.close()

GPIO.cleanup()

Arduino的代码

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

// TMP sensor connect to A0
#define PIN_TMP 0

int analogValue = 0;
float voltage = 0;
float celsius = 0;
int serialCmd;

LiquidCrystal_I2C lcd(0x27,16,2); 

void setup() {
  Serial.begin(9600);
  
  lcd.init();
  // lcd.backlight();
  lcd.print(“ALL CLEAR!”);
}

void loop() {
  analogValue = analogRead(PIN_TMP);
  voltage = analogValue * 5000.0 / 1024;
  celsius = (voltage – 500) / 10;
  
  // show temperature on LCD
  lcd.clear();
  lcd.print(celsius);
  
  // send to serial if necessary
  if(Serial.available() && Serial.read() == 71 /* G */) {
    Serial.println(celsius);
  }
  
  delay(1000);
}

#include <Wire.h>

#include <LiquidCrystal_I2C.h>

// TMP sensor connect to A0

#define PIN_TMP 0

int analogValue = 0;

float voltage = 0;

float celsius = 0;

int serialCmd;

LiquidCrystal_I2C lcd(0x27,16,2);

void setup() {

Serial.begin(9600);

lcd.init();

// lcd.backlight();

lcd.print(“ALL CLEAR!”);

}

void loop() {

analogValue = analogRead(PIN_TMP);

voltage = analogValue * 5000.0 / 1024;

celsius = (voltage – 500) / 10;

// show temperature on LCD

lcd.clear();

lcd.print(celsius);

// send to serial if necessary

if(Serial.available() && Serial.read() == 71 /* G */) {

Serial.println(celsius);

}

delay(1000);

}