tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_Freescale/TARGET_K20XX/analogin_api.c

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2015 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #include "mbed_assert.h"
  17 #include "analogin_api.h"
  18
  19 #include "cmsis.h"
  20 #include "pinmap.h"
  21 #include "clk_freqs.h"
  22 #include "PeripheralPins.h"
  23
  24 #define MAX_FADC        6000000
  25
  26 void analogin_init(analogin_t *obj, PinName pin) {
  27     obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
  28     MBED_ASSERT(obj->adc != (ADCName)NC);
  29
  30     SIM->SCGC6 |= SIM_SCGC6_ADC0_MASK;
  31
  32     uint32_t port = (uint32_t)pin >> PORT_SHIFT;
  33     SIM->SCGC5 |= 1 << (SIM_SCGC5_PORTA_SHIFT + port);
  34
  35     // bus clk
  36     uint32_t PCLK = bus_frequency();
  37     uint32_t clkdiv;
  38     for (clkdiv = 0; clkdiv < 4; clkdiv++) {
  39         if ((PCLK >> clkdiv) <= MAX_FADC)
  40             break;
  41     }
  42     if (clkdiv == 4)                    //Set max div
  43         clkdiv = 0x7;
  44
  45     ADC0->SC1[1] = ADC_SC1_ADCH(obj->adc);
  46
  47     ADC0->CFG1 = ADC_CFG1_ADLPC_MASK    // Low-Power Configuration
  48                | ADC_CFG1_ADIV(clkdiv & 0x3)       // Clock Divide Select
  49                | ADC_CFG1_ADLSMP_MASK   // Long Sample Time
  50                | ADC_CFG1_MODE(3)       // (16)bits Resolution
  51                | ADC_CFG1_ADICLK(clkdiv >> 2);    // Input Clock
  52
  53     ADC0->CFG2 = ADC_CFG2_MUXSEL_MASK   // ADxxb or ADxxa channels
  54                | ADC_CFG2_ADHSC_MASK    // High-Speed Configuration
  55                | ADC_CFG2_ADLSTS(0);    // Long Sample Time Select
  56
  57     ADC0->SC2 = ADC_SC2_REFSEL(0);      // Default Voltage Reference
  58
  59     ADC0->SC3 = ADC_SC3_AVGE_MASK       // Hardware Average Enable
  60               | ADC_SC3_AVGS(0);        // 4 Samples Averaged
  61
  62     pinmap_pinout(pin, PinMap_ADC);
  63 }
  64
  65 uint16_t analogin_read_u16(analogin_t *obj) {
  66     // start conversion
  67     ADC0->SC1[0] = ADC_SC1_ADCH(obj->adc);
  68
  69     // Wait Conversion Complete
  70     while ((ADC0->SC1[0] & ADC_SC1_COCO_MASK) != ADC_SC1_COCO_MASK);
  71
  72     return (uint16_t)ADC0->R[0];
  73 }
  74
  75 float analogin_read(analogin_t *obj) {
  76     uint16_t value = analogin_read_u16(obj);
  77     return (float)value * (1.0f / (float)0xFFFF);
  78 }