32 Rotary Encoder Peripheral
32 : Rotary Encoder Peripheral
- Author: Matt Venn
- Description: Reads a rotary encoder and stores the result in a register
- GitHub repository
- Open in 3D viewer
- Clock: 64000000 Hz
What it does
Reads up to 4 rotary (incremental) encoder: https://en.wikipedia.org/wiki/Incremental_encoder
The a and b signals are first debounced at a configurable frequency.
The encoder counts from 0 to 255.
Register map
| Address | Name | Access | Description |
|---|---|---|---|
| 0x00 | DATA | R | Value of Encoder 0 |
| 0x01 | DATA | R | Value of Encoder 1 |
| 0x02 | DATA | R | Value of Encoder 2 |
| 0x03 | DATA | R | Value of Encoder 3 |
| 0x04 | DATA | R/W | Debounce frequency. Will be left shifted by 4 |
How to test
Connect up to 4 incremental encoders to the input port (see pin mapping).
Use the test firmware to read the value of the encoder and print it out.
External hardware
Rotary incremental encoders. Most encoder Pmod boards have pull-up / pull-down resistors. If you are using a bare encoder, you will need to add your own pull-up / pull-down resistors.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | enc0 a | ||
| 1 | enc0 b | ||
| 2 | enc1 a | ||
| 3 | enc1 b | spi_miso | |
| 4 | enc2 a | spi_cs_n | |
| 5 | enc2 b | spi_clk | |
| 6 | enc3 a | spi_mosi | |
| 7 | enc3 b |