diff options
Diffstat (limited to 'max44009.lua')
| -rw-r--r-- | max44009.lua | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/max44009.lua b/max44009.lua new file mode 100644 index 0000000..325497b --- /dev/null +++ b/max44009.lua @@ -0,0 +1,24 @@ +local max44009 = {} +local device_address = 0x4a + +max44009.bus_id = 0 + +function max44009.read() + i2c.start(max44009.bus_id) + if not i2c.address(max44009.bus_id, device_address, i2c.TRANSMITTER) then + return + end + i2c.write(max44009.bus_id, {0x03, 0x04}) + i2c.stop(max44009.bus_id) + i2c.start(max44009.bus_id) + if not i2c.address(max44009.bus_id, device_address, i2c.RECEIVER) then + return + end + local data = i2c.read(max44009.bus_id, 2) + i2c.stop(max44009.bus_id) + local mantissa = bit.lshift(bit.band(string.byte(data, 1), 0x0f), 4) + bit.band(string.byte(data, 2), 0x0f) + local exponent = bit.rshift(bit.band(string.byte(data, 1), 0xf0), 4) + return bit.lshift(1, exponent) * mantissa * 0.045 +end + +return max44009 |