We live in a digital world, so the saying goes, but there are a lot of things around us are in analog. Readings from analog sensors such as a light-dependant resistor or a temperature sensor have to be converted to digital in order to be processed by a microcontroller/microprocessor. Unfortunately, board like the Raspberry Pi doesn't have analog input. In this situation, an external Analog-to-Digital Converter (ADC) and Digital-to-Analog Converter (DAC) module comes in handy.
This ADC/DAC module uses an 8-bit PCF8591 chip with I2C interface. It accepts 4 analog inputs and has 1 analog output. There are 3 analog sources on-board - a thermistor, a light-dependant resistor and a single-turn potentiometer. These sources are enabled by three jumpers. You can also connect up to four external analog sensors to the analog input pins of this board. Just remove the jumpers to disable the onboard sensors.
