Unverified Commit 67f2b3a2 authored by Birte Kristina Friesel's avatar Birte Kristina Friesel
Browse files

hardcode bus_id = 0. It's highly unlikely to change.

parent 40993ba5

scd4x.lua

+17 −19
Original line number Diff line number Diff line 
local scd4x = {}

local device_address = 0x62



scd4x.bus_id = 0

local addr = 0x62



function scd4x.start()

	i2c.start(scd4x.bus_id)

	if not i2c.address(scd4x.bus_id, device_address, i2c.TRANSMITTER) then

	i2c.start(0)

	if not i2c.address(0, addr, i2c.TRANSMITTER) then

		return false

	end

	i2c.write(scd4x.bus_id, {0x21, 0xb1})

	i2c.stop(scd4x.bus_id)

	i2c.write(0, {0x21, 0xb1})

	i2c.stop(0)

	return true

end



function scd4x.stop()

	i2c.start(scd4x.bus_id)

	if not i2c.address(scd4x.bus_id, device_address, i2c.TRANSMITTER) then

	i2c.start(0)

	if not i2c.address(0, addr, i2c.TRANSMITTER) then

		return false

	end

	i2c.write(scd4x.bus_id, {0x3f, 0x86})

	i2c.stop(scd4x.bus_id)

	i2c.write(0, {0x3f, 0x86})

	i2c.stop(0)

	return true

end



function scd4x.read()

	i2c.start(scd4x.bus_id)

	if not i2c.address(scd4x.bus_id, device_address, i2c.TRANSMITTER) then

	i2c.start(0)

	if not i2c.address(0, addr, i2c.TRANSMITTER) then

		return nil

	end

	i2c.write(scd4x.bus_id, {0xec, 0x05})

	i2c.stop(scd4x.bus_id)

	i2c.start(scd4x.bus_id)

	if not i2c.address(scd4x.bus_id, device_address, i2c.RECEIVER) then

	i2c.write(0, {0xec, 0x05})

	i2c.stop(0)

	i2c.start(0)

	if not i2c.address(0, addr, i2c.RECEIVER) then

		return nil

	end

	local data = i2c.read(scd4x.bus_id, 9)

	i2c.stop(scd4x.bus_id)

	local data = i2c.read(0, 9)

	i2c.stop(0)

	if not scd4x.crc_valid(data, 9) then

		return nil

	end