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https://github.com/scruss/micropython-mcp3001
MicroPython library for the MCP3001 10-bit 1-channel SPI Analogue-Digital converter
https://github.com/scruss/micropython-mcp3001
adc mcp3001 microchip micropython
Last synced: about 2 months ago
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MicroPython library for the MCP3001 10-bit 1-channel SPI Analogue-Digital converter
- Host: GitHub
- URL: https://github.com/scruss/micropython-mcp3001
- Owner: scruss
- License: mit
- Created: 2024-11-06T16:23:56.000Z (about 2 months ago)
- Default Branch: main
- Last Pushed: 2024-11-06T18:21:04.000Z (about 2 months ago)
- Last Synced: 2024-11-06T19:24:20.019Z (about 2 months ago)
- Topics: adc, mcp3001, microchip, micropython
- Language: Python
- Homepage: https://github.com/scruss/micropython-MCP3001
- Size: 140 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# micropython-MCP3001
MicroPython library for the MCP3001 10-bit 1-channel SPI
Analogue-Digital converter
This library enables an MCP3001 ADC to be used with any MicroPython
implementation that supports SPI. Almost all MicroPython-capable
boards have adequate ADCs onboard, so you might only want to use this
library if:
* your board has no ADC (like the Wemos
[W600-PICO](https://www.wemos.cc/en/latest/w600/w600_pico.html#w600-pico))
or a very limited one (as on the ESP8266); or
* you wish to use an external reference voltage source such as an
LM4040.
## Installation
Copy the `mcp3001.py` file to your MicroPython board's filesystem,
typically to the root or `/lib` folder.
## Usage
```python3
import mcp3001
# …
adc = mcp3001.MCP3001(spi, cs)
```
### Initialization
```
MCP3001(spi, cs [, ref_voltage])
```
* `spi` is an instance of a [Serial Peripheral Interface
bus](https://docs.micropython.org/en/latest/library/machine.SPI.html)
object, for example `spi = machine.SPI(0)`
* `cs` is an instance of an [I/O
pin](https://docs.micropython.org/en/latest/library/machine.Pin.html)
object, configured for output and ideally initially set high. An
example might be `cs = machine.Pin(17, machine.Pin.OUT, value=1)`
* `ref_voltage` is an optional argument to manually set the
reference voltage. If it is not specified as a float, the value of
3.3 is assumed.
### Methods
* `read()` — returns an integer ADC reading from 0–1023.
* `read_u16()` — returns an integer ADC reading from 0—65535. This
is provided for compatibility with MicroPython's
[method of the same name](https://docs.micropython.org/en/latest/library/machine.ADC.html#machine.ADC.read_u16).
* `read_v()` — returns a floating-point ADC reading from
0.0 – *reference voltage* volts.
* `reference_voltage()` — returns the ADC reference voltage as a
floating-point value. Returns 3.3 if none was given during
initialization.
## Example
An MCP3001 is used to read the value of a potentiometer into a
Raspberry Pi Pico. The brown wires in the diagram indicate analogue
ground, and have been kept separate from the black system ground
wires. If your board doesn't have a separate **AGND** connection, a
regular **GND** connection will do.
The default `SPI(0)` pins have been used on the Raspberry Pi Pico:
GP16 for RX, GP17 for CSn and GP18 for SCK. In the absence of an
external reference voltage, **3V3(OUT)** has been connected to
**VREF** on the MCP3001.
Code: [test_mcp3001.py](test_mcp3001.py)
## Device information
Datasheet: [MicroChip MCP3001 2.7V 10-Bit A/D Converter with SPI™
Serial
Interface](https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/21293C.pdf)
### Pinout
1. **VREF** — analogue reference voltage. Should not exceed
**VDD**.
2. **IN+** — Positive analogue input. While **IN+** and **IN-** form a
pseudo-differential pair, they can't float completely unrelated to
system voltages. Please refer to the datasheet.
3. **IN-** — Negative analogue input. Typically connected to
**VSS**, or analogue ground (**AGND**) if your
micro-controller has it.
4. **VSS** — Ground.
5. **CS/SHDN** — SPI
Chip Select (active low) and combined ADC shutdown line.
6. **DOUT** — SPI serial data out.
7. **CLK** — SPI serial data clock.
8. **VDD** — power supply, 2.7–5.5 V DC.
Note that the MCP3001, unlike other chips in the MCP300x range, has no
SPI **DIN** pin. Its entire operation is controlled by the
**CS/SHDN** pin, and
only the data out and clock lines are used.
## Credits
© Stewart Russell — scruss.com, 2024.
Based on Romilly Cocking's
[mcp3008.py](https://github.com/romilly/pico-code/blob/master/src/pico_code/pico/mcp3008/mcp3008.py)
library.