PCF8591-ADC-DAC Analog Digital Converter Module
|Power supply||+5V DC|
|Inputs||4 analog inputs programmable single-ended or differential input|
|ADC converter||8-bit successive approximation A / D converter|
|Module PCB size||3.6cm * 2.3cm|
|Interface||A serial I2C bus interface|
This particular module is suitable for tutorial use and perhaps for some hobbyists. Its drawback is that its I2C address is hard-wired to all zeros. (Note that I2C is a very effective 2-wire communications standard that is used by many small semiconductor devices such as microcontrollers and sensor peripherals.) If the address lines could be jumpered high or low, then several identical modules could be placed on the same I2C lines. I would therefore recommend the alternative module named the Mini PCF8591 AD DA Shell Module because it has that capability. It is also at least three times the price.
The IC permits only 8 bit data allowing only 256 steps in the analog output value or the digital output value. This is likely borderline for hobbyists who may want to build instrumentation or test equipment.
My tests show another frustration: A lower than expected analog output voltage. For a 4.88 volt supply the output is only 4.17 volts (85%) at maximum value setting. Since the maximum supply voltage is 8 volts, increasing the supply to 6 volts may get a 5 volt result. I did not remove the green LED and related resistor to see if the problem was simply an excess current drain from the IC’s AOUT.
Reference: PCF8591 8-bit A/D and D/A converter Product Specification, 2003-01-27, Philips Semiconductor.PCF8591 Module YL-40
The module is composed of:
- A PCF8591 IC at U1.
- A thermistor that measures temperature at R6.
- A photo-voltaic cell. This is a light sensitive resistor at R7.
- A single turn trimmer potentiometer at R3.
- Two LEDs: a red one that is on when the device has power; and a green one that increases brightness as the output voltage increases.
- Three red jumpers that apply the voltage sources – photo-voltaic cell, thermistor, and potentiometer, and to analog input channels AIN0, AIN1, and AIN3 respectively.
- Connector pins for I2C (SDA and SCL), Vcc, and ground.
- Connector pins for the Analog output AOUT, and pins for each of the three analog input channels.
- A 4-wire ribbon cable is included with sockets suitable for the connector pins.