串口操作在日常嵌入式设备调试的过程可以使用，而且非常方便，比较麻烦的应该是十六进制的接收处理。
python里面使用serial库来操作串口，serial的使用流程跟平常的类似，也是打开、关闭、读、写
1.打开串口
一般就是设置端口，波特率。
使用serial.Serial创建实体的时候会去打开串口，之后可以使用is_open开判断下是否串口是否打开正常。
def DOpenPort(portx, bps, timeout):
try:
# 打开串口，并得到串口对象
ser = serial.Serial(portx, bps, timeout=timeout)
# 判断是否打开成功
if(False == ser.is_open):
ser = -1
except Exception as e:
print("---异常---：", e)
return ser
2.关闭串口
使用ser.close即可关闭串口
def DColsePort(ser):
uart.fdstate = -1
ser.close()
3.写数据
数据的写使用ser.write接口，如果写的是十六进制的数据使用bytearray来定义，如writebuf = bytearray([0x55, 0xaa, 0x00, 0x01, 0x00, 0x00])
def DWritePort(ser, data):
result = ser.write(data) # 写数据
logging.info(ser)
logging.info("Write %s(%d)" % (data.hex(), result))
return result
4.读数据
读数据使用ser.read接口，一般会先使用in_waiting来判断下是否有数据，然后开始读
# 十六进制显示
def hexShow(argv):
try:
result = ''
hLen = len(argv)
for i in range(hLen):
hvol = argv[i]
hhex = '%02x' % hvol
result += hhex+' '
logging.info('Led Read:%s', result)
return result
except Exception as e:
print("---异常---：", e)
def DReadPort(ser):
# 循环接收数据，此为死循环，可用线程实现
readstr = ""
if ser.in_waiting:
readbuf = ser.read(ser.in_waiting)
if readbuf[0] == 0x55 and readbuf[1] == 0xaa:
readstr = readbuf
else:
readstr = readstr + readbuf
hexShow(readstr)
5.实例
下面举一个例子，说明下我们在实际的使用情况。
一般会单独创建一个进程来作为数据的接收，然后再配合上标记位或者信号量来处理逻辑
import serial # 导入模块
import threading
import time
import logging
import sys
class UartInfo(object):
def __init__(self, fd, count, fail):
self.fd = fd
self.count = count # 测试次数
self.fail = fail # 失败次数
response = False
image_addr = 0x00
image_crc = 0x00
version = 0
write_event = threading.Event()
uart = UartInfo(-1, 0, 0)
def logging_init():
logging.basicConfig(# filename="test.log", # 指定输出的文件
level=logging.DEBUG,
format='%(asctime)s - %(filename)s[line:%(lineno)d] - %(levelname)s: %(message)s')
return True
# 十六进制显示
def hexShow(argv):
try:
result = ''
hLen = len(argv)
for i in range(hLen):
hvol = argv[i]
hhex = '%02x' % hvol
result += hhex+' '
logging.info('Led Read:%s', result)
return result
except Exception as e:
print("---异常---：", e)
def crc_sum(data, data_len):
crc = 0
i = 0
while(i < data_len):
crc += data[i]
i += 1
return crc & 0x00FF
def crc_sum_u32(data, data_len):
crc = 0
i = 0
while(i < data_len):
crc += data[i]
i += 1
return crc
# 打开串口
def DOpenPort(portx, bps, timeout):
try:
# 打开串口，并得到串口对象
ser = serial.Serial(portx, bps, timeout=timeout)
# 判断是否打开成功
if(False == ser.is_open):
ser = -1
except Exception as e:
print("---异常---：", e)
return ser
# 关闭串口
def DColsePort(ser):
uart.fdstate = -1
ser.close()
# 写数据
def DWritePort(ser, data):
result = ser.write(data) # 写数据
logging.info(ser)
logging.info("Led Write %s(%d)" % (data.hex(), result))
return result
# 读数据
def ReadData_Thread(ser):
# 循环接收数据，此为死循环，可用线程实现
readstr = ""
while(-1 != ser):
if ser.in_waiting:
try: # 如果读取的不是十六进制数据--
readbuf = ser.read(ser.in_waiting)
if readbuf[0] == 0x55 and readbuf[1] == 0xaa:
readstr = readbuf
else:
readstr = readstr + readbuf
hexShow(readstr)
if (readstr[3] == 0x01) and (len(readstr) > 10):
uart.version = readstr[16]
uart.response = True
uart.write_event.set()
elif (readstr[3] == 0x21) and (readstr[4] == 0x00) and (readstr[5] == 0x00):
uart.response = True
uart.write_event.set()
elif (readstr[3] == 0x22) and (len(readstr) > 10):
uart.image_addr = (readstr[6] << 24 & 0xFF000000)
uart.image_addr += (readstr[7] << 16 & 0x00FF0000)
uart.image_addr += (readstr[8] << 8 & 0x0000FF00)
uart.image_addr += (readstr[9] << 0 & 0x000000FF)
uart.response = True
uart.write_event.set()
elif (readstr[3] == 0x23) and (len(readstr) > 25):
uart.response = True
uart.write_event.set()
except: # --则将其作为字符串读取
readbuf = ser.read(ser.in_waiting)
hexShow(readbuf)
def GetVersion(ser):
print("GetVersion")
writebuf = bytearray([0x55, 0xaa, 0x00, 0x01, 0x00, 0x00])
# crc
writebuf.append(crc_sum(writebuf, len(writebuf)))
DWritePort(ser, writebuf)
logging.info("take")
uart.response = False
uart.write_event.clear()
uart.write_event.wait(timeout=3)
uart.write_event.clear()
logging.info("give")
if uart.response == False:
logging.info("fail")
return False
else:
return True
# 测试任务
def Test_Thread(ser):
while (-1 != ser):
uart.response = False
uart.image_addr = 0x00
uart.image_crc = 0x00
uart.version = 0
logging.info("count:%d", uart.count)
logging.info("fail:%d", uart.fail)
print("count", uart.count)
print("fail", uart.fail)
if GetVersion(ser):
logging.info(uart.version)
if uart.version == 0x37:
otafile = "./UartV108.bin"
else:
otafile = "./UartV107.bin"
else:
uart.fail += 1
uart.count += 1
continue
print("ota:", otafile)
logging.info("ota:%s", otafile)
time.sleep(2)
uart.count += 1
time.sleep(5)
def TestStop(ser):
DColsePort(uart.fd) # 关闭串口
if __name__ == "__main__":
if 2 != len(sys.argv):
print("please enter COM")
exit()
else:
uart.tty = sys.argv[1]
logging_init()
uart.fd = DOpenPort(uart.tty, 115200, None)
if(uart.fd != -1): # 判断串口是否成功打开
threading.Thread(target=Test_Thread, args=(uart.fd,)).start()
threading.Thread(target=ReadData_Thread, args=(uart.fd,)).start()
