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Reading a Potentiometer on a Raspberry Pi 4B with an MCP3008 ADC

The Raspberry Pi has no analog input — read a real potentiometer's position using an MCP3008 ADC over SPI, with full wiring and Python code.

Try this directly in the free Raspberry Pi 4B simulator — no hardware or signup required. New to the GPIO header? Start with the interactive pinout guide.

What you’ll need

Raspberry Pi 4B
MCP3008 ADC
10kΩ Potentiometer

Step by step

Drag Raspberry Pi 4B onto the Canvas.
Drag the MCP3008 ADC onto the Canvas — a real DIP-16 chip, connects via drawn wires.
Drag the 10kΩ Potentiometer onto the Canvas.
Hover over every MCP3008 pin and note the exact labels shown (standard datasheet pins are CH0-CH7, VDD, VREF, AGND, CLK, DOUT, DIN, CS/SHDN, DGND — confirm against the actual on-screen labels).
Wire the MCP3008 to the Pi's fixed SPI pins (physical/BOARD numbering):

MCP3008 pin	Pi pin
VDD	3.3V
VREF	3.3V
AGND	GND
DGND	GND
CLK	Physical pin 23 (SCLK)
DOUT	Physical pin 21 (MISO)
DIN	Physical pin 19 (MOSI)
CS/SHDN	Physical pin 24 (CE0)

Wire the Potentiometer: GND → GND. VCC → 3.3V. SIG → MCP3008's CH0 (or whichever channel — note which one you used).

import spidev
import asyncio
 
spi = spidev.SpiDev()
spi.open(0, 0)
spi.max_speed_hz = 1350000
 
def read_channel(channel):
    adc = spi.xfer2([1, (8 + channel) << 4, 0])
    return ((adc[1] & 3) << 8) + adc[2]   # returns 0-1023
 
while True:
    value = read_channel(0)   # change to match whichever CH pin you wired
    print(f"Potentiometer value: {value}")
    await asyncio.sleep(0.5)

What “working correctly” looks like

Turning the knob fully counter-clockwise reads near 0, fully clockwise reads near 1023, with a smooth, proportional value in between.
The knob should physically stop at both ends of its travel.