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#!/usr/bin/env python3
import serial
import json
import re
class Usv(object):
def __init__(self, device, baudrate, json_file):
self._serial_port = serial.Serial(device,
baudrate=baudrate,
timeout=10)
# force a clean prompt
self._serial_port.write(b"\r")
self._read_until_prompt()
#print("cleaned prompt")
with open(json_file) as fhandle:
self.json_params = json.load(fhandle)
def _read_until_prompt(self):
# match on "\n=>"
prompt = False
inbuf = []
while not prompt:
inbuf.append(self._serial_port.read(1))
if len(inbuf) > 2:
if inbuf[-3] == b"\n" and \
inbuf[-2] == b"=" and inbuf[-1] == b">":
prompt = True
return inbuf
def get_parameters(self):
# [{'name': 'acvoltsin', 'index': 1},
results = {}
for parameter in self.json_params:
outbuf = "d %s\r" % parameter['num']
self._serial_port.write(outbuf.encode())
inbuf = self._read_until_prompt()
sbuf = ""
for char in inbuf:
sbuf += char.decode("utf-8")
#print("-->%s<--" % sbuf)
regex = parameter['regex']
match = re.search(regex, sbuf, re.MULTILINE)
if match:
name = parameter['name']
value = float(match.group(1))
results.setdefault(name, value)
#print("MATCH: %s: %f" % (name,value))
return results
if __name__ == "__main__":
import pprint
usv = Usv("/dev/ttyU0", 600, "usv_param.json")
parameters = usv.get_parameters()
pprint.pprint(parameters)
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