tmk_core/tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11XX_11CXX/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 static const PinMap PinMap_ADC[] = {
  23     {P0_11, ADC0_0, 2},
  24     {P1_0 , ADC0_1, 2},
  25     {P1_1 , ADC0_2, 2},
  26     {P1_2 , ADC0_3, 2},
  27     // {P1_3 , ADC0_4, 2}, -- should be mapped to SWDIO only
  28     {P1_4 , ADC0_5, 1},
  29     {P1_10, ADC0_6, 1},
  30     {P1_11, ADC0_7, 1},
  31     {NC   , NC    , 0}
  32 };
  33
  34 #define ANALOGIN_MEDIAN_FILTER      1
  35
  36 #define ADC_10BIT_RANGE             0x3FF
  37 #define ADC_12BIT_RANGE             0xFFF
  38
  39 static inline int div_round_up(int x, int y) {
  40   return (x + (y - 1)) / y;
  41 }
  42
  43 #define ADC_RANGE    ADC_10BIT_RANGE
  44
  45 void analogin_init(analogin_t *obj, PinName pin) {
  46     obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
  47     MBED_ASSERT(obj->adc != (uint32_t)NC);
  48
  49     // Power up ADC
  50     LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
  51     LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
  52
  53     uint32_t offset = (uint32_t)pin & 0xff;
  54     __IO uint32_t *reg = (__IO uint32_t*)(LPC_IOCON_BASE + offset);
  55
  56     // set pin to ADC mode
  57     *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
  58
  59     uint32_t PCLK = SystemCoreClock;
  60     uint32_t MAX_ADC_CLK = 4500000;
  61     uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
  62
  63     LPC_ADC->CR = (0 << 0)      // no channels selected
  64                 | (clkdiv << 8) // max of 4.5MHz
  65                 | (0 << 16)     // BURST = 0, software controlled
  66                 | ( 0 << 17 );  // CLKS = 0, not applicable
  67
  68     pinmap_pinout(pin, PinMap_ADC);
  69 }
  70
  71 static inline uint32_t adc_read(analogin_t *obj) {
  72     // Select the appropriate channel and start conversion
  73     LPC_ADC->CR &= ~0xFF;
  74     LPC_ADC->CR |= 1 << (int)obj->adc;
  75     LPC_ADC->CR |= 1 << 24;
  76
  77     // Repeatedly get the sample data until DONE bit
  78     unsigned int data;
  79     do {
  80         data = LPC_ADC->GDR;
  81     } while ((data & ((unsigned int)1 << 31)) == 0);
  82
  83     // Stop conversion
  84     LPC_ADC->CR &= ~(1 << 24);
  85
  86     return (data >> 6) & ADC_RANGE; // 10 bit
  87 }
  88
  89 static inline void order(uint32_t *a, uint32_t *b) {
  90     if (*a > *b) {
  91         uint32_t t = *a;
  92         *a = *b;
  93         *b = t;
  94     }
  95 }
  96
  97 static inline uint32_t adc_read_u32(analogin_t *obj) {
  98     uint32_t value;
  99 #if ANALOGIN_MEDIAN_FILTER
 100     uint32_t v1 = adc_read(obj);
 101     uint32_t v2 = adc_read(obj);
 102     uint32_t v3 = adc_read(obj);
 103     order(&v1, &v2);
 104     order(&v2, &v3);
 105     order(&v1, &v2);
 106     value = v2;
 107 #else
 108     value = adc_read(obj);
 109 #endif
 110     return value;
 111 }
 112
 113 uint16_t analogin_read_u16(analogin_t *obj) {
 114     uint32_t value = adc_read_u32(obj);
 115
 116     return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
 117 }
 118
 119 float analogin_read(analogin_t *obj) {
 120     uint32_t value = adc_read_u32(obj);
 121     return (float)value * (1.0f / (float)ADC_RANGE);
 122 }