Question

我试图通过pySerial将AT命令发送到SIM800模块。我遇到的问题是，当我发送命令时，我收到的消息是前一个命令的输出（或者有时是前一个命令本身）。我的代码如下所示：

import time
import serial

ser = serial.Serial()
ser.port = "/dev/ttyAMA0"
ser.baudrate = 9600
ser.open()

def readData():
    buffer = ""
    while True:
        oneByte = ser.read(1)
        if oneByte == b"\n":
            return buffer
        else:
            buffer += oneByte.decode("ascii")

def sendData(command, timeout):
    fullcommand = "{}\r\n".format(command)
    print "Sent: {}".format(fullcommand)
    ser.write(fullcommand)
    time.sleep(timeout)
    return

sendData("AT", 1) # Expecting "OK" back
print "Return: {}".format(readData()) # Prints AT

sendData("AT+CIPSHUT", 5) # Expecting "SHUT OK" back
print "Return: {}".format(readData()) # Prints OK

sendData("AT+CIPMUX=0", 2) # Expecting "OK" back
print "Return: {}".format(readData()) # Prints AT+CIPSHUT

sendData("AT+CSTT=\"myapn\"", 4) # Expecting "OK" back
print "Return: {}".format(readData()) # Prints SHUT OK

我觉得这与需要刷新缓冲区有关，但我对Serial工作没有太多经验。任何人都可以建议我做错了吗？

Answer 1

通过UART与SIM 800通讯时，我遇到了同样的问题。我使用ATE0命令禁用了回显。尝试此操作可能会对您有所帮助。

 import serial
 import time

 # dmesg | grep tty #to get which port it ts using
 port = serial.Serial("/dev/ttyO2", baudrate=9600, timeout=1)

 if port.isOpen():
     print(port.name + ' is open...!!!')

 # Transmitting AT Commands to the Modem
 port.write('AT'+'\r')
 print port.read(32)
 time.sleep(2)

 # To disable echo
 port.write('ATE0'+'\r')  
 print port.read(32)
 time.sleep(2)

Answer 2

一些事情。

如果要设置写入超时，则需要在write_timeout对象的初始化或设置Serial ser.write_timeout来完成>
如果您真的担心数据仍然在输入缓冲区中，您可以ser.reset_input_buffer()
如果您真的担心数据仍然在输出缓冲区中，您可以执行ser.reset_output_buffer()

现在在代码方面你可以做这样的事情

import time
import serial

ser = serial.Serial()
ser.port = "/dev/ttyAMA0"
ser.baudrate = 9600
ser.open()

def readData():
    buffer = ""
    while True:
        oneByte = ser.read(1)
        if oneByte == b"\n":
            return buffer
        else:
            buffer += oneByte.decode("ascii")

def sendData(command, timeout):
    fullcommand = "{}\r\n".format(command)
    ser.write_timeout = timeout # This is where you can set the timeout
    bytes_written = ser.write(fullcommand)
    # Check to see if all the data was written
    if bytes_written == len(fullcommand):
        print "Sent: {}".format(fullcommand)
    else:
        print 'Not all data transferred'

sendData("AT", 1) # Expecting "OK" back
print "Return: {}".format(readData()) # Prints AT

sendData("AT+CIPSHUT", 5) # Expecting "SHUT OK" back
print "Return: {}".format(readData()) # Prints OK

sendData("AT+CIPMUX=0", 2) # Expecting "OK" back
print "Return: {}".format(readData()) # Prints AT+CIPSHUT

sendData("AT+CSTT=\"myapn\"", 4) # Expecting "OK" back
print "Return: {}".format(readData()) # Prints SHUT OK

pySerial + SIM800 / 900 AT命令 - 读缓冲区包含之前的写缓冲区数据

2 个答案: