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[[Fichier:Pi-MCP3008-Analog.jpg]]
In order to read analog data we need to use the following pins:
* VDD (power), DGND (digital ground) to power the MCP3008 chip.
We also need four 'SPI' data pins:
* DOUT (Data Out from MCP3008),
* CLK (Clock pin),
* DIN (Data In from Raspberry Pi),
* and /CS (Chip Select).
Finally of course, a source of analog data, we'll be using the basic 10k trim pot.
The MCP3008 has a few more pins we need to connect: AGND (analog ground, used sometimes in precision circuitry, which this is not) connects to GND, and VREF (analog voltage reference, used for changing the 'scale' - we want the full scale so tie it to 3.3V)
Below is a wiring diagram. Connect the 3.3V cobbler pin to the left + rail and the GND pin to the right - rail. Connect the following pins for the MCP chip
* MCP3008 VDD -> 3.3V (red)
* MCP3008 VREF -> 3.3V (red)
* MCP3008 AGND -> GND (black)
* MCP3008 CLK -> #18 (orange)
* MCP3008 DOUT -> #23 (yellow)
* MCP3008 DIN -> #24 (blue)
* MCP3008 CS -> #25 (violet)
* MCP3008 DGND -> GND (black)
Next connect up the potentiometer:
* Pin #1 (left) goes to GND (black),
* Pin #2 (middle) connects to MCP3008 CH0 (analog input #0) with a gray wire,
* and #3 (right) connects to 3.3V (red)
Advanced users may note that the Raspberry Pi does have a hardware SPI interface (the cobbler pins are labeled MISO/MOSI/SCLK/CE0/CE1). The hardware SPI interface is super fast but not included in all distributions.
For that reason we are using a bit banged SPI implementation so the SPI pins can be any of the raspberry pi's GPIOs (assuming you update the script).
[[Fichier:Pi-MCP3008-Wiring.jpg]]
Source: AdaFruit.com
Source: AdaFruit.com