Clemens Valens
This is a part of the Kinetiszer project.
pwm.c@0:cb80470434eb, 2014-10-28 (annotated)
- Committer:
- Clemo
- Date:
- Tue Oct 28 12:19:42 2014 +0000
- Revision:
- 0:cb80470434eb
Error & warning free.
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| Clemo | 0:cb80470434eb | 1 | /* |
| Clemo | 0:cb80470434eb | 2 | Copyright 2013 Paul Soulsby www.soulsbysynths.com |
| Clemo | 0:cb80470434eb | 3 | This file is part of Atmegatron. |
| Clemo | 0:cb80470434eb | 4 | |
| Clemo | 0:cb80470434eb | 5 | Atmegatron is free software: you can redistribute it and/or modify |
| Clemo | 0:cb80470434eb | 6 | it under the terms of the GNU General Public License as published by |
| Clemo | 0:cb80470434eb | 7 | the Free Software Foundation, either version 3 of the License, or |
| Clemo | 0:cb80470434eb | 8 | (at your option) any later version. |
| Clemo | 0:cb80470434eb | 9 | |
| Clemo | 0:cb80470434eb | 10 | Atmegatron is distributed in the hope that it will be useful, |
| Clemo | 0:cb80470434eb | 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| Clemo | 0:cb80470434eb | 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| Clemo | 0:cb80470434eb | 13 | GNU General Public License for more details. |
| Clemo | 0:cb80470434eb | 14 | |
| Clemo | 0:cb80470434eb | 15 | You should have received a copy of the GNU General Public License |
| Clemo | 0:cb80470434eb | 16 | along with Atmegatron. If not, see <http://www.gnu.org/licenses/>. |
| Clemo | 0:cb80470434eb | 17 | */ |
| Clemo | 0:cb80470434eb | 18 | |
| Clemo | 0:cb80470434eb | 19 | //*****Pulse Width Modulation. This sets a portion of the waveform to 0. The amount of the waveform blanked is set by the LFO and LFO amount****** |
| Clemo | 0:cb80470434eb | 20 | |
| Clemo | 0:cb80470434eb | 21 | #include "atmegatron.h" |
| Clemo | 0:cb80470434eb | 22 | |
| Clemo | 0:cb80470434eb | 23 | //lets and gets |
| Clemo | 0:cb80470434eb | 24 | byte pwm_lfoamt = 0; |
| Clemo | 0:cb80470434eb | 25 | //LFO amount - stored as byte 0-31. represents the maximum proportion of waveform that can be blanked. |
| Clemo | 0:cb80470434eb | 26 | void PWM_Let_LFOAmt(byte newamt) |
| Clemo | 0:cb80470434eb | 27 | { |
| Clemo | 0:cb80470434eb | 28 | pwm_lfoamt = newamt; |
| Clemo | 0:cb80470434eb | 29 | } |
| Clemo | 0:cb80470434eb | 30 | |
| Clemo | 0:cb80470434eb | 31 | |
| Clemo | 0:cb80470434eb | 32 | byte PWM_Get_LFOAmt(void) |
| Clemo | 0:cb80470434eb | 33 | { |
| Clemo | 0:cb80470434eb | 34 | return pwm_lfoamt; |
| Clemo | 0:cb80470434eb | 35 | } |
| Clemo | 0:cb80470434eb | 36 | |
| Clemo | 0:cb80470434eb | 37 | //PWM meat |
| Clemo | 0:cb80470434eb | 38 | void PWM_Process(void) |
| Clemo | 0:cb80470434eb | 39 | { |
| Clemo | 0:cb80470434eb | 40 | byte i; |
| Clemo | 0:cb80470434eb | 41 | long curindex, maxindex; |
| Clemo | 0:cb80470434eb | 42 | if (pwm_lfoamt > 0) { //pwm on: |
| Clemo | 0:cb80470434eb | 43 | maxindex = (WAVE_LEN - pwm_lfoamt); //intermediate value - min possible index to start blanking |
| Clemo | 0:cb80470434eb | 44 | curindex = ((127 - LFO_Get_Level()) * (long)pwm_lfoamt * 8225 >> 21) + maxindex; //then multiply by lfo level (8225 >> 21 is a way of doing / 255, without using a slow divide) |
| Clemo | 0:cb80470434eb | 45 | for(i=curindex;i<WAVE_LEN;i++){ //blank the relevant part of the waveform |
| Clemo | 0:cb80470434eb | 46 | Wave_Let_Process(i, 0); |
| Clemo | 0:cb80470434eb | 47 | } |
| Clemo | 0:cb80470434eb | 48 | } |
| Clemo | 0:cb80470434eb | 49 | } |