如何以编程方式打开串口？

Question

我有一个连接到运行 Arch 的 Raspberry Pi 的 Arduino。

arduino没什么可做的，只是不断打印一些传感器数据：

#include<Arduino.h>

void setup() {
    Serial.begin(9600);
}

float temp = .0;
int lumen = 0;

void loop() {
    if(Serial.available()) {        
        temp = analogRead(4) * .4882812 - 273.15;
        lumen = analogRead(0);
        Serial.print(temp);
        Serial.print("|");
        Serial.print(lumen);
        Serial.println();
    }
    delay(10);
}

在 Raspberry 上，将运行以下脚本：

# run.py
#!/usr/bin/env python2
from arduino import Arduino
from poster import Poster
import time
import subprocess
import json

if __name__ == '__main__':
    with open("config.json") as config_fh:
        config = json.load(config_fh)
        print(config)

    base_url = config["URL"]
    security_token = config["KEY"]
    port = config["TTY"]

    arduino = Arduino(port=port)
    arduino.start()
    time.sleep(1)

    while True:
        is_door_open = arduino.is_door_open()
        temperature = arduino.get_temperature()

        print arduino.is_door_open()
        print arduino.get_temperature()

#       nmap = subprocess.Popen("./networkClientsInNetwork.sh", stdout = subprocess.PIPE, stderr = subprocess.PIPE)
#       network_clients_count = int(nmap.stdout.readlines()[0])
#       print network_clients_count

#       poster = Poster()
#       poster.post_door_state(base_url, arduino.is_door_open(), security_token)
#       poster.post_temperature(base_url, str(arduino.get_temperature()), security_token)
#       poster.post_clients(base_url, str(network_clients_count), security_token)

        time.sleep(3)


from threading import Thread
import serial
import random
import time

这是不断从串口获取值的线程：

class Arduino(Thread):
    def __init__(self, port):
        Thread.__init__(self, target=self.recieve)
        self.daemon = True
        self.last_recieved = None

        self.serial = self.configure_port(port)
        self.serial.open()

    def configure_port(self, port_id):
        ser = serial.Serial(port=port_id, timeout=1)
        ser.rtscts = True
        ser.dsrdtr = True

        return ser

    def recieve(self):
        while True:
            self.serial.flushInput()
            self.serial.flushOutput()
            if self.serial.isOpen():
                self.last_recieved = self.serial.readline().replace("\r\n", "").split("|")

    def getLastRecieved(self):
        return self.last_recieved

    def is_door_open(self):
        try:
            lumen = int(self.getLastRecieved()[1])
            return_val = lumen > 150
        except Exception:
            return_val = None
            pass

        return return_val

    def get_temperature(self):
        try:
            temperature = int(float(self.getLastRecieved()[0]))
            temperature_offset = -5
            return_val = int(temperature) + temperature_offset
        except Exception:
            return_val = None
            pass

        return return_val

现在，当我第一次启动

run.py

时，它永远不会从串口获取数据。他们永远都是

None

。

当我跑步时

ino serial

（开始

picocom

）

并点击 Enter，Arduino 将发送流中的所有数据。如果我通过Q退出picocom，然后启动

run.py

，python脚本可以从串口读取所有数据。

所以我想知道：我在初始化中缺少什么？如何通过

picocom

使用

python

自动进行串行端口初始化？

Answer 1

我通过提出问题来解决这个问题。我将 Arduino

loop

方法更改为：

void loop() {
    temp = analogRead(4) * .4882812 - 273.15;
    lumen = analogRead(0);
    Serial.print(temp);
    Serial.print("|");
    Serial.print(lumen);
    Serial.println();
    delay(10);
}

这将使

run.py

无需通过picocom进行

magic

初始化。虽然我仍然想知道

Serial.available()

期望什么作为输入。

Answer 2

import serial

ser=serial.Serial('/dev/ttyUSB0', 9600, timeout=3)

Answer 3

我使用以下代码使用 python 连接到我的 arduino 并接收数据：

import serial


class Arduino():

    def __init__(self):
        try:
            self.arduino = serial.Serial('/dev/ttyUSB0', 9600)
            self.receivethread = threading.Thread(target=self.receive)
            #self.receivethread.start()
        except serial.error as message:
            pass
        except threading.ThreadError as message:
            pass
        except Exception as message:
            pass
    
    def receive(self):
        while True:
            if self.arduino.open():
                try:
                    datapacket = self.arduino.readline(30, chr(0))
                except Exception as message:
                    pass
                except serial.error as message:
                    pass
            else:
                    pass

        return datapacket