from time import sleep

from datetime import datetime, time as datetime_time, timedelta

#my import

import config

import bus

from utils.common import get_time

import app_logger

from RootSensor import RootSensor

cmd_on_off_auto_calib = 0x79 # if param 0xa0 - it will enable, otherwise will disable

cmd_get_co2 = 0x86

cmd_calibrate_zero = 0x87

cmd_calibrate_span = 0x88

cmd_sensor_detection_range = 0x99 # param not implemented - read datasheet

# Function to calculate MH-Z19 crc according to datasheet

def crc8(a):

crc = 0x00

count = 1

b = bytearray(a)

if len(b) < 8:

app_logger.error("crc array must be at least 8 bytes, but we have only: "+str(len(b))+", values: "+str(b))

return -1

while count < 8:

crc += b[count]

count = count+1

# Truncate to 8 bit

crc %= 256

# Invert number with xor

crc = ~crc & 0xFF

crc += 1

return crc

class CO2(RootSensor):

uart_bus=None

data_bus=None

max_read_try=5

measure_count=0

def __init__(self):

super().__init__()

self.uart_bus=bus.UartBus.UartBus()

def probe(self):

if not self.uart_bus or not self.uart_bus.probe(): #UART bus not exist

return False

if self.read_val()!=-1:

return True

app_logger.warn("CO2 sensor not responded")

return False

def send_cmd(self, cmd, param=None):

cmd_template = bytearray()

cmd_template.append(0xff)

cmd_template.append(0x01)

cmd_template.append(cmd)

if param:

cmd_template.append(param>>8)

cmd_template.append(param)

else:

cmd_template.append(0x00)

cmd_template.append(0x00)

cmd_template.append(0x00)

cmd_template.append(0x00)

cmd_template.append(0x00)

cmd_template.append(crc8(cmd_template))

self.uart_bus.write(cmd_template)

def zero_calibrate(self):

with self.lock:

try:

self.uart_bus.acqure_lock_switch_to_measure_co2()

self.send_cmd(cmd_calibrate_zero)

except Exception:

app_logger.exception("CO2 calibrate exception:")

#esceptions here appearing constantly so just forget about it ?

pass

finally:

self.uart_bus.release_lock_switch()

def read_co2(self):

with self.lock:

co2value = -1

temperature = 25

try:

self.uart_bus.acqure_lock_switch_to_measure_co2()

for i in range(0, 5): # trying couple times, because got crc error ?

#self.uart_bus.release_lock_switch()

#self.uart_bus.acqure_lock_switch_to_measure_co2()

sleep(0.1) #for stabilize processes

# Send "read value" command to MH-Z19 sensor

self.send_cmd(cmd_get_co2)

s = self.uart_bus.read(9)

if(len(s) != 9):

app_logger.error(str(datetime.now())+", error, uart data len in response: "+str(len(s)))

continue

crc = crc8(s)

# Calculate crc

if crc != s[8]:

if i == (self.max_read_try-1): #for not spam

app_logger.error('CO2 CRC error calculated, try %d, crc calc=0x%x bytes= %x:%x:%x:%x:%x:%x:%x:%x crc= 0x%x, date=%s\n' % (

i, crc, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7], s[8], str(datetime.now()) ))

continue

if s[0] != 0xFF or s[1] != cmd_get_co2:

if i == (self.max_read_try-1): #for not spam

app_logger.error('CO2 wrong answer to command %d bytes= %d:%d:%d:%d:%d:%d:%d:%d crc= %d\n' % (

cmd_get_co2, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7], s[8]))

continue

co2value = s[2] * 256 + s[3]

temperature = s[4]-40

break

except Exception:

app_logger.exception("CO2 read exception:")

#esceptions here appearing constantly so just forget about it ?

finally:

self.uart_bus.release_lock_switch()

#app_logger.info("CO2 : "+str(co2value))

return co2value, temperature

def read_val(self):

co2value, temperature=self.read_co2()

self.data_bus.CO2=co2value

if not hasattr(config, "GPIO_GET_TEMP_HUMID"):

#in case not exist good temperature sensor - try to measure what we have with rough

self.data_bus.temperature=temperature

return self.data_bus.CO2

def get_status_str(self):

if not self.data_bus.CO2:

self.read_val()

return "CO2: "+str(self.data_bus.CO2)