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local mh_z19 = {}
mh_z19.c_query = string.char(0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79)
mh_z19.co2 = nil
mh_z19.temp = nil
mh_z19.abc_count = nil
mh_z19.abc_ticks = nil
function checksum(b1, b2, b3, b4, b5, b6, b7)
return 0xff - ((b1 + b2 + b3 + b4 + b5 + b6 + b7) % 0x100) + 1
end
function mh_z19.parse_frame(data)
local start, cmd, co2h, co2l, temp, u1, abc_ticks, abc_count, cksum = struct.unpack("BBBBBBBBB", data)
if start ~= 0xff or cmd ~= 0x86 then
return false
end
if checksum(cmd, co2h, co2l, temp, u1, abc_ticks, abc_count) ~= cksum then
return false
end
mh_z19.co2 = co2h * 256 + co2l
mh_z19.temp = temp - 40
mh_z19.abc_ticks = abc_ticks
mh_z19.abc_count = abc_count
return true
end
return mh_z19
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