Microchip PIC specific D2A
Ubicom SX specific D2A
Analog to Digital Conversion
Don Hyde says:
An R-2R ladder can be used to turn a group of [digital] output pins into a DAC for a few cents. Below is a 3-bit DAC. Using 3 [digital] output pins (beware of the odball open drain pins, they're no good for this), this circuit will provide 0 - Vcc*(7/8) volts out, with a 2R source impedence.
It can be extended to more bits by replicating the MSB R-2R end of the ladder.
Up to 4 bits can be achieved with 5% resistors.
Up to 6 bits can be achieved with 1% resistors.
In many applications, it would be advisable to buffer the output with an op-amp.
A circuit like this can achieve waaay higher output frequencies than PWM, and can be easier to filter, at the expense of using up a bunch of pins.OUT o--+-/\/\/\/\----o MSB | 2R \ / \ R / | +-/\/\/\/\----o Middle bit | 2R \ / R \ / +-/\/\/\/\----o LSB | 2R \ / \ 2R / | --- ///
PICList Thread '[EE]: high res DA challenge'
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