1 /* 2 * Author: Thomas Ingleby <thomas.c.ingleby (at) intel.com> 3 * Copyright (c) 2014 Intel Corporation. 4 * 5 * Permission is hereby granted, free of charge, to any person obtaining 6 * a copy of this software and associated documentation files (the 7 * "Software"), to deal in the Software without restriction, including 8 * without limitation the rights to use, copy, modify, merge, publish, 9 * distribute, sublicense, and/or sell copies of the Software, and to 10 * permit persons to whom the Software is furnished to do so, subject to 11 * the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be 14 * included in all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 17 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 19 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 20 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 21 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 22 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 23 */ 24 25 #pragma once 26 27 /** 28 * @file 29 * @brief Pulse Width Modulation module 30 * 31 * PWM is the Pulse Width Modulation interface to libmraa. It allows the 32 * generation of a signal on a pin. Some boards may have higher or lower levels 33 * of resolution so make sure you check the board & pin you are using before 34 * hand. 35 * 36 * @snippet cycle-pwm3.c Interesting 37 */ 38 39 #ifdef __cplusplus 40 extern "C" { 41 #endif 42 43 #include <stdio.h> 44 #include <fcntl.h> 45 46 #include "common.h" 47 48 typedef struct _pwm* mraa_pwm_context; 49 50 /** 51 * Initialise pwm_context, uses board mapping 52 * 53 * @param pin The PWM PIN 54 * @return pwm context or NULL 55 */ 56 mraa_pwm_context mraa_pwm_init(int pin); 57 58 /** 59 * Initialise pwm_context, raw mode 60 * 61 * @param chipid The chip inwhich the PWM is under in SYSFS 62 * @param pin The PWM PIN. 63 * @return pwm context or NULL 64 */ 65 mraa_pwm_context mraa_pwm_init_raw(int chipid, int pin); 66 67 /** 68 * Set the ouput duty-cycle percentage, as a float 69 * 70 * @param dev The Pwm context to use 71 * @param percentage A floating-point value representing percentage of output. 72 * The value should lie between 0.0f (representing on 0%) and 1.0f 73 * Values above or below this range will be set at either 0.0f or 1.0f 74 * @return Result of operation 75 */ 76 mraa_result_t mraa_pwm_write(mraa_pwm_context dev, float percentage); 77 78 /** 79 * Read the ouput duty-cycle percentage, as a float 80 * 81 * @param dev The Pwm context to use 82 * @return percentage A floating-point value representing percentage of output. 83 * The value should lie between 0.0f (representing on 0%) and 1.0f 84 * Values above or below this range will be set at either 0.0f or 1.0f 85 */ 86 float mraa_pwm_read(mraa_pwm_context dev); 87 88 /** 89 * Set the PWM period as seconds represented in a float 90 * 91 * @param dev The Pwm context to use 92 * @param seconds Period represented as a float in seconds 93 * @return Result of operation 94 */ 95 mraa_result_t mraa_pwm_period(mraa_pwm_context dev, float seconds); 96 97 /** 98 * Set period, milliseconds. 99 * 100 * @param dev The Pwm context to use 101 * @param ms Milliseconds for period 102 * @return Result of operation 103 */ 104 mraa_result_t mraa_pwm_period_ms(mraa_pwm_context dev, int ms); 105 106 /** 107 * Set period, microseconds 108 * 109 * @param dev The Pwm context to use 110 * @param us Microseconds as period 111 * @return Result of operation 112 */ 113 mraa_result_t mraa_pwm_period_us(mraa_pwm_context dev, int us); 114 115 /** 116 * Set pulsewidth, As represnted by seconds in a (float) 117 * 118 * @param dev The Pwm context to use 119 * @param seconds The duration of a pulse 120 * @return Result of operation 121 */ 122 mraa_result_t mraa_pwm_pulsewidth(mraa_pwm_context dev, float seconds); 123 124 /** 125 * Set pulsewidth, milliseconds 126 * 127 * @param dev The Pwm context to use 128 * @param ms Milliseconds for pulsewidth 129 * @return Result of operation 130 */ 131 mraa_result_t mraa_pwm_pulsewidth_ms(mraa_pwm_context dev, int ms); 132 133 /** 134 * Set pulsewidth, microseconds 135 * 136 * @param dev The Pwm context to use 137 * @param us Microseconds for pulsewidth 138 * @return Result of operation 139 */ 140 mraa_result_t mraa_pwm_pulsewidth_us(mraa_pwm_context dev, int us); 141 142 /** 143 * Set the enable status of the PWM pin. None zero will assume on with output being driven. 144 * and 0 will disable the output. 145 * 146 * @param dev The pwm context to use 147 * @param enable Toggle status of pin 148 * @return Result of operation. 149 */ 150 mraa_result_t mraa_pwm_enable(mraa_pwm_context dev, int enable); 151 152 /** 153 * Change ownership of context 154 * 155 * @param dev the context 156 * @param owner Ownership boolean 157 * @return Result of operation 158 */ 159 mraa_result_t mraa_pwm_owner(mraa_pwm_context dev, mraa_boolean_t owner); 160 161 /** 162 * Close and unexport the PWM pin 163 * 164 * @param dev The pwm context to use 165 * @return Result of operation 166 */ 167 mraa_result_t mraa_pwm_close(mraa_pwm_context dev); 168 169 /** 170 * Set Both Period and DutyCycle on a PWM context 171 * 172 * @param dev The pwm context to use 173 * @param period represented in ms. 174 * @param duty dutycycle of the pwm signal. 175 * @return Result of operation 176 */ 177 mraa_result_t mraa_pwm_config_ms(mraa_pwm_context dev, int period, float duty); 178 179 /** 180 * Set Both Period and DutyCycle on a PWM context. Duty represented as percentage. 181 * 182 * @param dev The pwm context to use 183 * @param period represented in ms. 184 * @param duty duty percantage. i.e. 50% = 0.5f 185 * @return Result of operation 186 */ 187 mraa_result_t mraa_pwm_config_percent(mraa_pwm_context dev, int period, float duty); 188 189 /** 190 * Get the maximum pwm period in us 191 * 192 * @return max pwm in us 193 */ 194 int mraa_pwm_get_max_period(); 195 196 /** 197 * Get the minimum pwm period in us 198 * 199 * @return min pwm in us 200 */ 201 int mraa_pwm_get_min_period(); 202 203 #ifdef __cplusplus 204 } 205 #endif 206
