PCF8591

Here’s the optimized FAQ for your PCF8591 library in the requested format:

1. No Communication (ACK Not Received)

Q: My PCF8591 doesn’t respond to I2C commands.
A:

• Verify PCF8591_Init() was called first
• Check device address (default 0x48, configurable via A0-A2 pins)
• Ensure 4.7kΩ pull-up resistors on SDA/SCL
• Confirm power supply (2.5V-6V) is stable

2. ADC Reading Issues

Q: ADC always returns 0 or 255.
A:

• Check AREF pin has proper voltage reference
• Verify input voltage is within 0-VREF range
• Call PCF8591_ReadADC() twice (discard first reading)

3. Noisy ADC Readings

Q: ADC values fluctuate randomly.
A:

• Add 0.1µF capacitor between AIN pins and GND
• Use differential mode for noisy environments
• Keep analog wires short and away from digital lines

4. DAC Output Problems

Q: No output on AOUT pin.
A:

• Enable DAC first with PCF8591_EnableDAC()
• Check DAC value range (0-255 maps to 0-VREF)
• Add 10kΩ load resistor between AOUT and GND

5. Differential Mode Errors

Q: Differential readings show wrong values.
A:

• Ensure input voltages are within specified range
• For AIN3-AIN0 mode, verify AIN3 > AIN0
• Switch to single-ended mode for troubleshooting

6. Simultaneous ADC/DAC Operation

Q: How to use ADC and DAC together?
A:

7. Channel Selection Problems

Q: Wrong channel being read.
A:

• Valid channels are 0-3 (AIN0-AIN3)
• Check _adc_mode matches your configuration
• For differential modes, use correct channel pairs