A small IC chip
controls the backlight intensity with an analog signal provided by one
channel of a 2 channel DAC on the I2C bus.The extra DAC channel is provided on
the header shown.The DAC is
8-bit and converts an input level from 0-255 into a voltage between 0 and 3.3
V.The useful range of the
backlight driver is less than that however.Anything above about 1.25 V (setting
of ~100) translates into full intensity.To save power (especially in battery powered setups) it is a good idea
to dim the backlight when not in use.
