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I2C

The following example receives data from a light sensor using I2C. Sensor used is the BH1750FVI Digital Light Sensor.

import time
from machine import I2C
import bh1750fvi

i2c = I2C(0, I2C.MASTER, baudrate=100000)
light_sensor = bh1750fvi.BH1750FVI(i2c, addr=i2c.scan()[0])

while(True):
        data = light_sensor.read()
        print(data)
    time.sleep(1)

Drivers for the BH1750FVI

Place this sample code into a file named bh1750fvi.py. This can then be imported as a library.

# Simple driver for the BH1750FVI digital light sensor

class BH1750FVI:
    MEASUREMENT_TIME = const(120)

    def __init__(self, i2c, addr=0x23, period=150):
        self.i2c = i2c
        self.period = period
        self.addr = addr
        self.time = 0
        self.value = 0
        self.i2c.writeto(addr, bytes([0x10])) # start continuos 1 Lux readings every 120ms

    def read(self):
        self.time += self.period
        if self.time >= MEASUREMENT_TIME:
            self.time = 0
            data = self.i2c.readfrom(self.addr, 2)
            self.value = (((data[0] << 8) + data[1]) * 1200) // 1000
        return self.value

Light sensor and LoRa

This is the same code, with added LoRa connectivity, sending the lux value from the light sensor to another LoRa enabled device.

import socket
import time
import pycom
import struct
from network import LoRa
from machine import I2C
import bh1750fvi

LORA_PKG_FORMAT = "!BH"
LORA_CONFIRM_FORMAT = "!BB"

DEVICE_ID = 1

pycom.heartbeat(False)

lora = LoRa(mode=LoRa.LORA, tx_iq=True, region=LoRa.EU868)
lora_sock = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
lora_sock.setblocking(False)

i2c = I2C(0, I2C.MASTER, baudrate=100000)
light_sensor = bh1750fvi.BH1750FVI(i2c, addr=i2c.scan()[0])

while(True):
    msg = struct.pack(LORA_PKG_FORMAT, DEVICE_ID, light_sensor.read())
    lora_sock.send(msg)

    pycom.rgbled(0x150000)

    wait = 5
    while (wait > 0):
        wait = wait - 0.1
        time.sleep(0.1)
        recv_data = lora_sock.recv(64)

        if (len (recv_data) >= 2):
            status, device_id = struct.unpack(LORA_CONFIRM_FORMAT, recv_data)

            if (device_id == DEVICE_ID and status == 200):
                pycom.rgbled(0x001500)
                wait = 0

    time.sleep(1)

 

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