The Pi lacks analogue inputs. The Waveshare ADC HAT adds a high-precision ADC for accurate voltage, temperature, and sensor measurements.
Why ADC for Pi?
Raspberry Pi has no analogue GPIO pins. An ADC converts analogue voltages to digital values the Pi can read.
Specs
- ADS1256 (24-bit) or ADS1115 (16-bit) ADC
- 8 channels (ADS1256) or 4 channels (ADS1115)
- Sample rate: 30,000 SPS (ADS1256) or 860 SPS (ADS1115)
- SPI (ADS1256) or I2C (ADS1115) interface
Setup
# For ADS1115:
pip3 install adafruit-circuitpython-ads1x15Python Code
import board, busio
import adafruit_ads1x15.ads1115 as ADS
from adafruit_ads1x15.analog_in import AnalogIn
i2c = busio.I2C(board.SCL, board.SDA)
ads = ADS.ADS1115(i2c)
chan = AnalogIn(ads, ADS.P0)
print(f"Voltage: {chan.voltage:.4f}V, Raw: {chan.value}")Projects
- Precision voltage measurement for power supply testing
- Load cell / strain gauge reading for weighing
- Thermocouple reading for high-temperature measurement
- Multi-channel environmental sensor logging
- Audio signal analysis (low-frequency)
Frequently Asked Questions
ADS1256 vs ADS1115?
ADS1256: 24-bit, 8 channels, faster, SPI. ADS1115: 16-bit, 4 channels, slower, simpler I2C.
Accuracy?
ADS1256 resolves microvolts. ADS1115 resolves millivolts. Both far exceed most sensor requirements.
Can I read 0-10V signals?
Not directly. Use a voltage divider to scale down to the ADC’s input range (typically 0-3.3V or 0-5V).
Sample rate sufficient for audio?
ADS1256 at 30 kSPS covers up to ~15 kHz (Nyquist). Adequate for low-frequency audio analysis.
Conclusion
The ADC HAT unlocks the analogue world for Pi, enabling precision measurements impossible with digital-only GPIO.
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