@ -57,70 +57,78 @@ susceptible to noise, you must choose a debounce method that will also mitigate
if the scanning is slow, and you are using a timestamp-based algorithm, you might end up making a debouncing decision based on only two
sampled values, which will limit the noise-resistance of the algorithm.
* Currently all built-in debounce algorithms support timestamp-based debouncing only. In the future we might
implement cycles-based debouncing, and it will be selectable via a ```config.h``` macro.
implement cycles-based debouncing, and it will be selectable via a `config.h` macro.
2) Symmetric vs Asymmetric
* Symmetric - apply the same debouncing algorithm, to both key-up and key-down events.
* Recommended naming convention: ```sym_*```
* Recommended naming convention: `sym_*`
* Asymmetric - apply different debouncing algorithms to key-down and key-up events. E.g. Eager key-down, Defer key-up.
* Recommended naming convention: ```asym_*``` followed by details of the type of algorithm in use, in order, for key-down and then key-up
* Recommended naming convention: `asym_*` followed by details of the type of algorithm in use, in order, for key-down and then key-up
3) Eager vs Defer
* Eager - any key change is reported immediately. All further inputs for DEBOUNCE ms are ignored.
* Eager algorithms are not noise-resistant.
* Recommended naming conventions:
* ```sym_eager_*```
* ```asym_eager_*_*```: key-down is using eager algorithm
* ```asym_*_eager_*```: key-up is using eager algorithm
* `sym_eager_*`
* `asym_eager_*_*`: key-down is using eager algorithm
* `asym_*_eager_*`: key-up is using eager algorithm
* Defer - wait for no changes for DEBOUNCE ms before reporting change.
* Defer algorithms are noise-resistant
* Recommended naming conventions:
* ```sym_defer_*```
* ```asym_defer_*_*```: key-down is using defer algorithm
* ```asym_*_defer_*```: key-up is using defer algorithm
* `sym_defer_*`
* `asym_defer_*_*`: key-down is using defer algorithm
* `asym_*_defer_*`: key-up is using defer algorithm
4) Global vs Per-Key vs Per-Row
* Global - one timer for all keys. Any key change state affects global timer
* Recommended naming convention: ```*_g```
* Recommended naming convention: `*_g`
* Per-key - one timer per key
* Recommended naming convention: ```*_pk```
* Recommended naming convention: `*_pk`
* Per-row - one timer per row
* Recommended naming convention: ```*_pr```
* Recommended naming convention: `*_pr`
* Per-key and per-row algorithms consume more resources (in terms of performance,
and ram usage), but fast typists might prefer them over global.
## Supported Debounce Algorithms
QMK supports multiple debounce algorithms through its debounce API.
QMK supports multiple algorithms through its debounce API.
### Debounce selection
### Debounce Time
Keyboards may select one of the core debounce methods by adding the following line into ```rules.mk```:
Default debounce time is 5 milliseconds and it can be changed with the following line in `config.h`:
```
#define DEBOUNCE 10
```
?> Setting `DEBOUNCE` to `0` will disable this feature.
### Debounce Method
Keyboards may select one of the core debounce methods by adding the following line into `rules.mk`:
```
DEBOUNCE_TYPE = <nameofalgorithm>
```
Name of algorithm is one of:
| Algorithm | Description |
| ------------------------- | ----------- |
| ```sym_defer_g``` | Debouncing per keyboard. On any state change, a global timer is set. When ```DEBOUNCE``` milliseconds of no changes has occurred, all input changes are pushed. This is the highest performance algorithm with lowest memory usage and is noise-resistant. |
| ```sym_defer_pr``` | Debouncing per row. On any state change, a per-row timer is set. When ```DEBOUNCE``` milliseconds of no changes have occurred on that row, the entire row is pushed. This can improve responsiveness over `sym_defer_g` while being less susceptible to noise than per-key algorithm. |
| ```sym_defer_pk``` | Debouncing per key. On any state change, a per-key timer is set. When ```DEBOUNCE``` milliseconds of no changes have occurred on that key, the key status change is pushed. |
| ```sym_eager_pr``` | Debouncing per row. On any state change, response is immediate, followed by ```DEBOUNCE``` milliseconds of no further input for that row. |
| ```sym_eager_pk``` | Debouncing per key. On any state change, response is immediate, followed by ```DEBOUNCE``` milliseconds of no further input for that key. |
| ```asym_eager_defer_pk``` | Debouncing per key. On a key-down state change, response is immediate, followed by ```DEBOUNCE``` milliseconds of no further input for that key. On a key-up state change, a per-key timer is set. When ```DEBOUNCE``` milliseconds of no changes have occurred on that key, the key-up status change is pushed. |
| Algorithm | Description |
| --------------------- | ----------- |
| `sym_defer_g` | Debouncing per keyboard. On any state change, a global timer is set. When `DEBOUNCE` milliseconds of no changes has occurred, all input changes are pushed. This is the highest performance algorithm with lowest memory usage and is noise-resistant. |
| `sym_defer_pr` | Debouncing per row. On any state change, a per-row timer is set. When `DEBOUNCE` milliseconds of no changes have occurred on that row, the entire row is pushed. This can improve responsiveness over `sym_defer_g` while being less susceptible to noise than per-key algorithm. |
| `sym_defer_pk` | Debouncing per key. On any state change, a per-key timer is set. When `DEBOUNCE` milliseconds of no changes have occurred on that key, the key status change is pushed. |
| `sym_eager_pr` | Debouncing per row. On any state change, response is immediate, followed by `DEBOUNCE` milliseconds of no further input for that row. |
| `sym_eager_pk` | Debouncing per key. On any state change, response is immediate, followed by `DEBOUNCE` milliseconds of no further input for that key. |
| `asym_eager_defer_pk` | Debouncing per key. On a key-down state change, response is immediate, followed by `DEBOUNCE` milliseconds of no further input for that key. On a key-up state change, a per-key timer is set. When `DEBOUNCE` milliseconds of no changes have occurred on that key, the key-up status change is pushed. |
?> ```sym_defer_g``` is the default if ```DEBOUNCE_TYPE``` is undefined
?> `sym_defer_g` is the default if `DEBOUNCE_TYPE` is undefined.
?> ```sym_eager_pr``` is suitable for use in keyboards where refreshing ```NUM_KEYS``` 8-bit counters is computationally expensive or has low scan rate while fingers usually hit one row at a time. This could be appropriate for the ErgoDox models where the matrix is rotated 90°. Hence its "rows" are really columns and each finger only hits a single "row" at a time with normal usage.
?> `sym_eager_pr` is suitable for use in keyboards where refreshing `NUM_KEYS` 8-bit counters is computationally expensive or has low scan rate while fingers usually hit one row at a time. This could be appropriate for the ErgoDox models where the matrix is rotated 90°. Hence its "rows" are really columns and each finger only hits a single "row" at a time with normal usage.
### Implementing your own debouncing code
You have the option to implement you own debouncing algorithm with the following steps:
* Set ```DEBOUNCE_TYPE = custom``` in ```rules.mk```.
* Add ```SRC += debounce.c``` in ```rules.mk```
* Implement your own ```debounce.c```. See ```quantum/debounce``` for examples.
* Set `DEBOUNCE_TYPE = custom` in `rules.mk`.
* Add `SRC += debounce.c` in `rules.mk`
* Implement your own `debounce.c`. See `quantum/debounce` for examples.
* Debouncing occurs after every raw matrix scan.
* Use num_rows instead of MATRIX_ROWS to support split keyboards correctly.
* If your custom algorithm is applicable to other keyboards, please consider making a pull request.
tzarc
1 year ago