Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Freescale/TARGET_KLXX/pwmout_api.c@0:9b334a45a8ff, 2015-10-01 (annotated)

Committer:
bogdanm
Date:
Thu Oct 01 15:25:22 2015 +0300
Revision:
0:9b334a45a8ff
Child:
144:ef7eb2e8f9f7
Initial commit on mbed-dev



Replaces mbed-src (now inactive)

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bogdanm 0:9b334a45a8ff 1 /* mbed Microcontroller Library
bogdanm 0:9b334a45a8ff 2 * Copyright (c) 2006-2013 ARM Limited
bogdanm 0:9b334a45a8ff 3 *
bogdanm 0:9b334a45a8ff 4 * Licensed under the Apache License, Version 2.0 (the "License");
bogdanm 0:9b334a45a8ff 5 * you may not use this file except in compliance with the License.
bogdanm 0:9b334a45a8ff 6 * You may obtain a copy of the License at
bogdanm 0:9b334a45a8ff 7 *
bogdanm 0:9b334a45a8ff 8 * http://www.apache.org/licenses/LICENSE-2.0
bogdanm 0:9b334a45a8ff 9 *
bogdanm 0:9b334a45a8ff 10 * Unless required by applicable law or agreed to in writing, software
bogdanm 0:9b334a45a8ff 11 * distributed under the License is distributed on an "AS IS" BASIS,
bogdanm 0:9b334a45a8ff 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
bogdanm 0:9b334a45a8ff 13 * See the License for the specific language governing permissions and
bogdanm 0:9b334a45a8ff 14 * limitations under the License.
bogdanm 0:9b334a45a8ff 15 */
bogdanm 0:9b334a45a8ff 16 #include "mbed_assert.h"
bogdanm 0:9b334a45a8ff 17 #include "pwmout_api.h"
bogdanm 0:9b334a45a8ff 18
bogdanm 0:9b334a45a8ff 19 #include "cmsis.h"
bogdanm 0:9b334a45a8ff 20 #include "pinmap.h"
bogdanm 0:9b334a45a8ff 21 #include "clk_freqs.h"
bogdanm 0:9b334a45a8ff 22 #include "PeripheralPins.h"
bogdanm 0:9b334a45a8ff 23
bogdanm 0:9b334a45a8ff 24 static float pwm_clock;
bogdanm 0:9b334a45a8ff 25
bogdanm 0:9b334a45a8ff 26 void pwmout_init(pwmout_t* obj, PinName pin) {
bogdanm 0:9b334a45a8ff 27 // determine the channel
bogdanm 0:9b334a45a8ff 28 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
bogdanm 0:9b334a45a8ff 29 MBED_ASSERT(pwm != (PWMName)NC);
bogdanm 0:9b334a45a8ff 30
bogdanm 0:9b334a45a8ff 31 uint32_t clkdiv = 0;
bogdanm 0:9b334a45a8ff 32 float clkval;
bogdanm 0:9b334a45a8ff 33
bogdanm 0:9b334a45a8ff 34 #if defined(TARGET_KL43Z)
bogdanm 0:9b334a45a8ff 35 if (mcgirc_frequency()) {
bogdanm 0:9b334a45a8ff 36 SIM->SOPT2 |= SIM_SOPT2_TPMSRC(3); // Clock source: MCGIRCLK
bogdanm 0:9b334a45a8ff 37 clkval = mcgirc_frequency() / 1000000.0f;
bogdanm 0:9b334a45a8ff 38 } else {
bogdanm 0:9b334a45a8ff 39 SIM->SOPT2 |= SIM_SOPT2_TPMSRC(1); // Clock source: IRC48M
bogdanm 0:9b334a45a8ff 40 clkval = CPU_INT_IRC_CLK_HZ / 1000000.0f;
bogdanm 0:9b334a45a8ff 41 }
bogdanm 0:9b334a45a8ff 42 #else
bogdanm 0:9b334a45a8ff 43 if (mcgpllfll_frequency()) {
bogdanm 0:9b334a45a8ff 44 SIM->SOPT2 |= SIM_SOPT2_TPMSRC(1); // Clock source: MCGFLLCLK or MCGPLLCLK
bogdanm 0:9b334a45a8ff 45 clkval = mcgpllfll_frequency() / 1000000.0f;
bogdanm 0:9b334a45a8ff 46 } else {
bogdanm 0:9b334a45a8ff 47 SIM->SOPT2 |= SIM_SOPT2_TPMSRC(2); // Clock source: ExtOsc
bogdanm 0:9b334a45a8ff 48 clkval = extosc_frequency() / 1000000.0f;
bogdanm 0:9b334a45a8ff 49 }
bogdanm 0:9b334a45a8ff 50 #endif
bogdanm 0:9b334a45a8ff 51 while (clkval > 1) {
bogdanm 0:9b334a45a8ff 52 clkdiv++;
bogdanm 0:9b334a45a8ff 53 clkval /= 2.0;
bogdanm 0:9b334a45a8ff 54 if (clkdiv == 7)
bogdanm 0:9b334a45a8ff 55 break;
bogdanm 0:9b334a45a8ff 56 }
bogdanm 0:9b334a45a8ff 57
bogdanm 0:9b334a45a8ff 58 pwm_clock = clkval;
bogdanm 0:9b334a45a8ff 59 unsigned int port = (unsigned int)pin >> PORT_SHIFT;
bogdanm 0:9b334a45a8ff 60 unsigned int tpm_n = (pwm >> TPM_SHIFT);
bogdanm 0:9b334a45a8ff 61 unsigned int ch_n = (pwm & 0xFF);
bogdanm 0:9b334a45a8ff 62
bogdanm 0:9b334a45a8ff 63 SIM->SCGC5 |= 1 << (SIM_SCGC5_PORTA_SHIFT + port);
bogdanm 0:9b334a45a8ff 64 SIM->SCGC6 |= 1 << (SIM_SCGC6_TPM0_SHIFT + tpm_n);
bogdanm 0:9b334a45a8ff 65
bogdanm 0:9b334a45a8ff 66 TPM_Type *tpm = (TPM_Type *)(TPM0_BASE + 0x1000 * tpm_n);
bogdanm 0:9b334a45a8ff 67 tpm->SC = TPM_SC_CMOD(1) | TPM_SC_PS(clkdiv); // (clock)MHz / clkdiv ~= (0.75)MHz
bogdanm 0:9b334a45a8ff 68 tpm->CONTROLS[ch_n].CnSC = (TPM_CnSC_MSB_MASK | TPM_CnSC_ELSB_MASK); /* No Interrupts; High True pulses on Edge Aligned PWM */
bogdanm 0:9b334a45a8ff 69
bogdanm 0:9b334a45a8ff 70 obj->CnV = &tpm->CONTROLS[ch_n].CnV;
bogdanm 0:9b334a45a8ff 71 obj->MOD = &tpm->MOD;
bogdanm 0:9b334a45a8ff 72 obj->CNT = &tpm->CNT;
bogdanm 0:9b334a45a8ff 73
bogdanm 0:9b334a45a8ff 74 // default to 20ms: standard for servos, and fine for e.g. brightness control
bogdanm 0:9b334a45a8ff 75 pwmout_period_ms(obj, 20);
bogdanm 0:9b334a45a8ff 76 pwmout_write (obj, 0);
bogdanm 0:9b334a45a8ff 77
bogdanm 0:9b334a45a8ff 78 // Wire pinout
bogdanm 0:9b334a45a8ff 79 pinmap_pinout(pin, PinMap_PWM);
bogdanm 0:9b334a45a8ff 80 }
bogdanm 0:9b334a45a8ff 81
bogdanm 0:9b334a45a8ff 82 void pwmout_free(pwmout_t* obj) {}
bogdanm 0:9b334a45a8ff 83
bogdanm 0:9b334a45a8ff 84 void pwmout_write(pwmout_t* obj, float value) {
bogdanm 0:9b334a45a8ff 85 if (value < 0.0) {
bogdanm 0:9b334a45a8ff 86 value = 0.0;
bogdanm 0:9b334a45a8ff 87 } else if (value > 1.0) {
bogdanm 0:9b334a45a8ff 88 value = 1.0;
bogdanm 0:9b334a45a8ff 89 }
bogdanm 0:9b334a45a8ff 90
bogdanm 0:9b334a45a8ff 91 *obj->CnV = (uint32_t)((float)(*obj->MOD + 1) * value);
bogdanm 0:9b334a45a8ff 92 *obj->CNT = 0;
bogdanm 0:9b334a45a8ff 93 }
bogdanm 0:9b334a45a8ff 94
bogdanm 0:9b334a45a8ff 95 float pwmout_read(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 96 float v = (float)(*obj->CnV) / (float)(*obj->MOD + 1);
bogdanm 0:9b334a45a8ff 97 return (v > 1.0) ? (1.0) : (v);
bogdanm 0:9b334a45a8ff 98 }
bogdanm 0:9b334a45a8ff 99
bogdanm 0:9b334a45a8ff 100 void pwmout_period(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 101 pwmout_period_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 102 }
bogdanm 0:9b334a45a8ff 103
bogdanm 0:9b334a45a8ff 104 void pwmout_period_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 105 pwmout_period_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 106 }
bogdanm 0:9b334a45a8ff 107
bogdanm 0:9b334a45a8ff 108 // Set the PWM period, keeping the duty cycle the same.
bogdanm 0:9b334a45a8ff 109 void pwmout_period_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 110 float dc = pwmout_read(obj);
bogdanm 0:9b334a45a8ff 111 *obj->MOD = (uint32_t)(pwm_clock * (float)us) - 1;
bogdanm 0:9b334a45a8ff 112 pwmout_write(obj, dc);
bogdanm 0:9b334a45a8ff 113 }
bogdanm 0:9b334a45a8ff 114
bogdanm 0:9b334a45a8ff 115 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 116 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 117 }
bogdanm 0:9b334a45a8ff 118
bogdanm 0:9b334a45a8ff 119 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 120 pwmout_pulsewidth_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 121 }
bogdanm 0:9b334a45a8ff 122
bogdanm 0:9b334a45a8ff 123 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 124 *obj->CnV = (uint32_t)(pwm_clock * (float)us);
bogdanm 0:9b334a45a8ff 125 }