Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/analogout_api.c@147:ba84b7dc41a7, 2016-09-10 (annotated)

Committer:
JojoS
Date:
Sat Sep 10 15:32:04 2016 +0000
Revision:
147:ba84b7dc41a7
Parent:
144:ef7eb2e8f9f7 
added prescaler for 16 bit timers (solution as in LPC11xx), default prescaler 31 for max 28 ms period time

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /***************************************************************************//**
<> 144:ef7eb2e8f9f7 2 * @file analogout_aoi.c
<> 144:ef7eb2e8f9f7 3 *******************************************************************************
<> 144:ef7eb2e8f9f7 4 * @section License
<> 144:ef7eb2e8f9f7 5 * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b>
<> 144:ef7eb2e8f9f7 6 *******************************************************************************
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * SPDX-License-Identifier: Apache-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Licensed under the Apache License, Version 2.0 (the "License"); you may
<> 144:ef7eb2e8f9f7 11 * not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 12 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 13 *
<> 144:ef7eb2e8f9f7 14 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 15 *
<> 144:ef7eb2e8f9f7 16 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 17 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
<> 144:ef7eb2e8f9f7 18 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 19 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 20 * limitations under the License.
<> 144:ef7eb2e8f9f7 21 *
<> 144:ef7eb2e8f9f7 22 ******************************************************************************/
<> 144:ef7eb2e8f9f7 23
<> 144:ef7eb2e8f9f7 24 #include "device.h"
<> 144:ef7eb2e8f9f7 25 #if DEVICE_ANALOGOUT
<> 144:ef7eb2e8f9f7 26
<> 144:ef7eb2e8f9f7 27 #include "mbed_assert.h"
<> 144:ef7eb2e8f9f7 28 #include "error.h"
<> 144:ef7eb2e8f9f7 29 #include "analogout_api.h"
<> 144:ef7eb2e8f9f7 30 #include "pinmap.h"
<> 144:ef7eb2e8f9f7 31 #include "pinmap_function.h"
<> 144:ef7eb2e8f9f7 32 #include "PeripheralPins.h"
<> 144:ef7eb2e8f9f7 33 #include "clocking.h"
<> 144:ef7eb2e8f9f7 34
<> 144:ef7eb2e8f9f7 35 #include "em_dac.h"
<> 144:ef7eb2e8f9f7 36 #include "em_cmu.h"
<> 144:ef7eb2e8f9f7 37
<> 144:ef7eb2e8f9f7 38 static uint8_t dac_initialized = 0;
<> 144:ef7eb2e8f9f7 39
<> 144:ef7eb2e8f9f7 40 void analogout_init(dac_t *obj, PinName pin)
<> 144:ef7eb2e8f9f7 41 {
<> 144:ef7eb2e8f9f7 42 /* init in-memory structure */
<> 144:ef7eb2e8f9f7 43 obj->dac = (DAC_TypeDef *) pinmap_peripheral(pin, PinMap_DAC);
<> 144:ef7eb2e8f9f7 44 MBED_ASSERT((int) obj->dac != NC);
<> 144:ef7eb2e8f9f7 45
<> 144:ef7eb2e8f9f7 46 obj->channel = pin_location(pin, PinMap_DAC);
<> 144:ef7eb2e8f9f7 47 MBED_ASSERT((int) obj->channel != NC);
<> 144:ef7eb2e8f9f7 48
<> 144:ef7eb2e8f9f7 49 pin_mode(pin, Disabled);
<> 144:ef7eb2e8f9f7 50
<> 144:ef7eb2e8f9f7 51 if (!dac_initialized) {
<> 144:ef7eb2e8f9f7 52 /* Initialize the DAC. Will disable both DAC channels, so should only be done once */
<> 144:ef7eb2e8f9f7 53 /* Use default settings */
<> 144:ef7eb2e8f9f7 54 CMU_ClockEnable(cmuClock_DAC0, true);
<> 144:ef7eb2e8f9f7 55
<> 144:ef7eb2e8f9f7 56 DAC_Init_TypeDef init = DAC_INIT_DEFAULT;
<> 144:ef7eb2e8f9f7 57
<> 144:ef7eb2e8f9f7 58 /* Calculate the DAC clock prescaler value that will result in a DAC clock
<> 144:ef7eb2e8f9f7 59 * close to 500kHz. Second parameter is zero. This uses the current HFPERCLK
<> 144:ef7eb2e8f9f7 60 * frequency instead of setting a new one. */
<> 144:ef7eb2e8f9f7 61 init.prescale = DAC_PrescaleCalc(500000, REFERENCE_FREQUENCY);
<> 144:ef7eb2e8f9f7 62
<> 144:ef7eb2e8f9f7 63 /* Set reference voltage to VDD */
<> 144:ef7eb2e8f9f7 64 init.reference = dacRefVDD;
<> 144:ef7eb2e8f9f7 65
<> 144:ef7eb2e8f9f7 66 DAC_Init(obj->dac, &init);
<> 144:ef7eb2e8f9f7 67 dac_initialized = 1;
<> 144:ef7eb2e8f9f7 68 }
<> 144:ef7eb2e8f9f7 69 /* Use default channel settings */
<> 144:ef7eb2e8f9f7 70 DAC_InitChannel_TypeDef initChannel = DAC_INITCHANNEL_DEFAULT;
<> 144:ef7eb2e8f9f7 71 initChannel.enable = true;
<> 144:ef7eb2e8f9f7 72 DAC_InitChannel(obj->dac, &initChannel, obj->channel);
<> 144:ef7eb2e8f9f7 73 }
<> 144:ef7eb2e8f9f7 74
<> 144:ef7eb2e8f9f7 75 void analogout_free(dac_t *obj)
<> 144:ef7eb2e8f9f7 76 {
<> 144:ef7eb2e8f9f7 77 //Reset channel by re-initializing
<> 144:ef7eb2e8f9f7 78 DAC_InitChannel_TypeDef initChannel = DAC_INITCHANNEL_DEFAULT;
<> 144:ef7eb2e8f9f7 79 initChannel.enable = false;
<> 144:ef7eb2e8f9f7 80 DAC_InitChannel(obj->dac, &initChannel, obj->channel);
<> 144:ef7eb2e8f9f7 81
<> 144:ef7eb2e8f9f7 82 //Check all channels to see if we can disable the DAC completely
<> 144:ef7eb2e8f9f7 83 if((DAC0->CH0CTRL & DAC_CH0CTRL_EN) == 0 && (DAC0->CH1CTRL & DAC_CH1CTRL_EN) == 0) {
<> 144:ef7eb2e8f9f7 84 CMU_ClockEnable(cmuClock_DAC0, false);
<> 144:ef7eb2e8f9f7 85 dac_initialized = 0;
<> 144:ef7eb2e8f9f7 86 }
<> 144:ef7eb2e8f9f7 87 }
<> 144:ef7eb2e8f9f7 88
<> 144:ef7eb2e8f9f7 89 static inline void dac_write(dac_t *obj, int value)
<> 144:ef7eb2e8f9f7 90 {
<> 144:ef7eb2e8f9f7 91 switch (obj->channel) {
<> 144:ef7eb2e8f9f7 92 case 0:
<> 144:ef7eb2e8f9f7 93 obj->dac->CH0DATA = value;
<> 144:ef7eb2e8f9f7 94 break;
<> 144:ef7eb2e8f9f7 95 case 1:
<> 144:ef7eb2e8f9f7 96 obj->dac->CH1DATA = value;
<> 144:ef7eb2e8f9f7 97 break;
<> 144:ef7eb2e8f9f7 98 }
<> 144:ef7eb2e8f9f7 99 }
<> 144:ef7eb2e8f9f7 100
<> 144:ef7eb2e8f9f7 101 static inline int dac_read(dac_t *obj)
<> 144:ef7eb2e8f9f7 102 {
<> 144:ef7eb2e8f9f7 103 switch (obj->channel) {
<> 144:ef7eb2e8f9f7 104 case 0:
<> 144:ef7eb2e8f9f7 105 return obj->dac->CH0DATA;
<> 144:ef7eb2e8f9f7 106 break;
<> 144:ef7eb2e8f9f7 107 case 1:
<> 144:ef7eb2e8f9f7 108 return obj->dac->CH1DATA;
<> 144:ef7eb2e8f9f7 109 break;
<> 144:ef7eb2e8f9f7 110 default:
<> 144:ef7eb2e8f9f7 111 error("AnalogOut pin error. Invalid channel");
<> 144:ef7eb2e8f9f7 112 return -1;
<> 144:ef7eb2e8f9f7 113 break;
<> 144:ef7eb2e8f9f7 114 }
<> 144:ef7eb2e8f9f7 115 }
<> 144:ef7eb2e8f9f7 116
<> 144:ef7eb2e8f9f7 117 void analogout_write(dac_t *obj, float value)
<> 144:ef7eb2e8f9f7 118 {
<> 144:ef7eb2e8f9f7 119 /* We multiply the float value with 0xFFF because the DAC has 12-bit resolution.
<> 144:ef7eb2e8f9f7 120 * Ie. accepts values between 0 and 0xFFF (4096). */
<> 144:ef7eb2e8f9f7 121 dac_write(obj, value*0xFFF);
<> 144:ef7eb2e8f9f7 122 }
<> 144:ef7eb2e8f9f7 123
<> 144:ef7eb2e8f9f7 124 void analogout_write_u16(dac_t *obj, uint16_t value)
<> 144:ef7eb2e8f9f7 125 {
<> 144:ef7eb2e8f9f7 126 /* The DAC has 12 bit resolution, so we remove the 4 least significant bits */
<> 144:ef7eb2e8f9f7 127 dac_write(obj, value >> 4);
<> 144:ef7eb2e8f9f7 128 }
<> 144:ef7eb2e8f9f7 129
<> 144:ef7eb2e8f9f7 130 float analogout_read(dac_t *obj)
<> 144:ef7eb2e8f9f7 131 {
<> 144:ef7eb2e8f9f7 132 /* dac_read returns a number between 0 and 0xFFF. Division gives us a float between 0 and 1 */
<> 144:ef7eb2e8f9f7 133 return dac_read(obj)/(float)0xFFF;
<> 144:ef7eb2e8f9f7 134 }
<> 144:ef7eb2e8f9f7 135
<> 144:ef7eb2e8f9f7 136 uint16_t analogout_read_u16(dac_t *obj)
<> 144:ef7eb2e8f9f7 137 {
<> 144:ef7eb2e8f9f7 138 /* dac_read returns a number with 12 significant digits,
<> 144:ef7eb2e8f9f7 139 * so we shift in 0s from right to make it a 16 bit number */
<> 144:ef7eb2e8f9f7 140 return dac_read(obj) << 4;
<> 144:ef7eb2e8f9f7 141 }
<> 144:ef7eb2e8f9f7 142
<> 144:ef7eb2e8f9f7 143 #endif