Callbacks¶
Python-lpd8 works with callbacks to let you know that a pad has been pressed or a knob has been turned. Information about which program’s pad/knob has been actuated is passed to the callback.
Signature¶
Any callback function must have a signature compatible to the following:
-
callback(programNum: int, padNum: int, knobNum: int, value: int, noteon: int, noteoff: int, cc: int, pc: int)¶ Parameters: - programNum – Index of program pad/knob belongs to
- padNum – Index of pad that triggered call
- knobNum – Index of knob that triggered call
- value – Velocity for pads, value for knobs
- noteon – midi note of noteon message
- noteoff – midi note of noteoff message
- cc – midi control of control change message
- pc – midi program of program change message
The signature allows you to attach the same callback to all pads and knobs in all three modes. There are four possible calling schemes depending on the modes used:
Pad in PAD mode¶
In pad mode you will get one call on pad press, and another one on pad release. You can differentiate between the two by checking if noteon/noteoff is None. They will always be mutually exclusive.
| Param | Value press | Value release |
|---|---|---|
| programNum | 0-3 | 0-3 |
| padNum | 0-7 | 0-7 |
| knobNum | None | None |
| value | 1-127 | 0 |
| noteon | 0-127 | None |
| noteoff | None | 0-127 |
| cc | None | None |
| pc | None | None |
Pad in CC mode¶
- In cc mode you will get one call on pad press, and another one on pad release. The only way to differentiate between the
- two is to check if value is 0.
| Param | Value press | Value release |
|---|---|---|
| programNum | 0-3 | 0-3 |
| padNum | 0-7 | 0-7 |
| knobNum | None | None |
| value | 1-127 | 0 |
| noteon | None | None |
| noteoff | None | None |
| cc | 0-127 | 0-127 |
| pc | None | None |
Pad in PROG CHNG mode¶
In program change mode you will only get a call when the button is pressed. You also get no velocity data.
| Param | Value press |
|---|---|
| programNum | 0-3 |
| padNum | 0-7 |
| knobNum | None |
| value | None |
| noteon | None |
| noteoff | None |
| cc | None |
| pc | 0-127 |
Knob¶
The knob behaves the same way in all three modes. You get the position of the knob as the value.
| Param | Value turn |
|---|---|
| programNum | 0-3 |
| padNum | None |
| knobNum | 0-7 |
| value | 0-127 |
| noteon | None |
| noteoff | None |
| cc | 0-127 |
| pc | None |