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#!/usr/bin/env python3
import smbus
import argparse
import asyncio
import json
import logging
logger = logging.getLogger(__name__)
bus = None
lock = asyncio.Lock()
delay = 0.01
async def si7021_read():
async with lock:
await asyncio.sleep(delay)
# these are still blocking... meh
raw = bus.read_i2c_block_data(0x40, 0xE3, 2)
temp = 175.72 * (raw[0] << 8 | raw[1]) / 65536.0 - 46.85
raw = bus.read_i2c_block_data(0x40, 0xE5, 2)
rh = 125.0 * (raw[0] << 8 | raw[1]) / 65536.0 - 6.0
return rh, temp
async def handle_client(reader, writer):
request = None
while request != 'quit':
try:
request = await reader.read(255)
if request == b'\x04':
break
request = request.decode('utf-8').strip()
except Exception:
break
if request == 'read':
try:
rh, temp = await asyncio.wait_for(si7021_read(), timeout=3)
data = dict(humidity=rh, temp=temp)
except asyncio.TimeoutError as e:
logger.exception(e)
data = dict(error='i2c call timed out')
else:
data = dict(error='invalid request')
writer.write((json.dumps(data) + '\r\n').encode('utf-8'))
try:
await writer.drain()
except ConnectionResetError:
pass
writer.close()
async def run_server(host, port):
server = await asyncio.start_server(handle_client, host, port)
async with server:
logger.info('Server started.')
await server.serve_forever()
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument('--host', type=str, default='127.0.0.1')
parser.add_argument('--port', type=int, default=8306)
parser.add_argument('--bus', type=int, default=0,
help='Bus number (X for /dev/i2c-X)')
parser.add_argument('--delay', type=float, default=delay,
help='Delay before reading')
args = parser.parse_args()
delay = args.delay
logging.basicConfig(level=logging.INFO)
bus = smbus.SMBus(args.bus)
try:
asyncio.run(run_server(args.host, args.port))
except KeyboardInterrupt:
logging.info('Exiting...')
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