tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11U6X/analogin_api.c

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 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 #include "cmsis.h"
  19 #include "pinmap.h"
  20 #include "mbed_error.h"
  21
  22 #if DEVICE_ANALOGIN
  23
  24 #define ANALOGIN_MEDIAN_FILTER      1
  25
  26 #define ADC_10BIT_RANGE             0x3FF
  27 #define ADC_12BIT_RANGE             0xFFF
  28 #define PDRUN_VALID_BITS            0x000025FFL
  29 #define PDRUN_RESERVED_ONE          0x0000C800L
  30
  31 #define ADC_RANGE                   ADC_12BIT_RANGE
  32
  33 static const PinMap PinMap_ADC[] = {
  34     {P1_9 , ADC_0, 3},
  35     {P0_23, ADC_1, 1},
  36     {P0_16, ADC_2, 1},
  37     {P0_15, ADC_3, 3},
  38     {P1_22, ADC_4, 3},
  39     {P1_3 , ADC_5, 4},
  40     {P0_14, ADC_6, 2},
  41     {P0_13, ADC_7, 2},
  42     {P0_12, ADC_8, 2},
  43     {P0_11, ADC_9, 2},
  44     {P1_29, ADC_10,4},
  45     {P0_22, ADC_11,1},
  46     {NC   , NC    ,0}
  47 };
  48
  49
  50 void analogin_init(analogin_t *obj, PinName pin) {
  51     volatile uint32_t tmp;
  52     obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
  53     MBED_ASSERT(obj->adc != (ADCName)NC);
  54
  55     pinmap_pinout(pin, PinMap_ADC);
  56
  57     __IO uint32_t *reg = (__IO uint32_t*)(LPC_IOCON_BASE + (pin & 0x1FF));
  58     // set pin to ADC mode
  59     *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
  60
  61     // ADC Powered
  62     tmp = (LPC_SYSCON->PDRUNCFG & PDRUN_VALID_BITS);
  63     tmp &= ~((1 << 4) & PDRUN_VALID_BITS);
  64     LPC_SYSCON->PDRUNCFG = (tmp | PDRUN_RESERVED_ONE);
  65
  66     // Enable clock for ADC
  67     LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 13);
  68
  69     // Determine the clock divider for a 500kHz ADC clock during calibration
  70     uint32_t clkdiv = (SystemCoreClock / 500000) - 1;
  71
  72     // Perform a self-calibration
  73     LPC_ADC->CTRL = (1UL << 30) | (clkdiv & 0xFF);
  74     while ((LPC_ADC->CTRL & (1UL << 30)) != 0);
  75
  76     // Sampling clock: SystemClock divided by 1
  77     LPC_ADC->CTRL = 0;
  78 }
  79
  80 static inline uint32_t adc_read(analogin_t *obj) {
  81
  82     // select channel
  83     LPC_ADC->SEQA_CTRL &= ~(0xFFF);
  84     LPC_ADC->SEQA_CTRL |= (1UL << obj->adc);
  85
  86     // start conversion, sequence enable with async mode
  87     LPC_ADC->SEQA_CTRL |= ((1UL << 26) | (1UL << 31) | (1UL << 19));
  88
  89     // Repeatedly get the sample data until DONE bit
  90     volatile uint32_t data;
  91     do {
  92         data = LPC_ADC->SEQA_GDAT;
  93     } while ((data & (1UL << 31)) == 0);
  94     data = LPC_ADC->DAT[obj->adc];
  95
  96     // Stop conversion
  97     LPC_ADC->SEQA_CTRL &= ~(1UL << 31);
  98
  99     return ((data >> 4) & ADC_RANGE);
 100 }
 101
 102 static inline void order(uint32_t *a, uint32_t *b) {
 103     if (*a > *b) {
 104         uint32_t t = *a;
 105         *a = *b;
 106         *b = t;
 107     }
 108 }
 109
 110 static inline uint32_t adc_read_u32(analogin_t *obj) {
 111     uint32_t value;
 112 #if ANALOGIN_MEDIAN_FILTER
 113     uint32_t v1 = adc_read(obj);
 114     uint32_t v2 = adc_read(obj);
 115     uint32_t v3 = adc_read(obj);
 116     order(&v1, &v2);
 117     order(&v2, &v3);
 118     order(&v1, &v2);
 119     value = v2;
 120 #else
 121     value = adc_read(obj);
 122 #endif
 123     return value;
 124 }
 125
 126 uint16_t analogin_read_u16(analogin_t *obj) {
 127     uint32_t value = adc_read_u32(obj);
 128     return (value << 4) | ((value >> 8) & 0x000F); // 12 bit
 129 }
 130
 131 float analogin_read(analogin_t *obj) {
 132     uint32_t value = adc_read_u32(obj);
 133     return (float)value * (1.0f / (float)ADC_RANGE);
 134 }
 135
 136 #endif