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targets/TARGET_Silicon_Labs/TARGET_EFM32/analogout_api.c@165:2dd56e6daeec, 2017-05-23 (annotated)

Committer:
ranaumarnaeem
Date:
Tue May 23 12:54:50 2017 +0000
Revision:
165:2dd56e6daeec
Parent:
150:02e0a0aed4ec 
jhjg

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"
<> 150:02e0a0aed4ec 28 #include "mbed_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