tmk_core/tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC13XX/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 #define ANALOGIN_MEDIAN_FILTER      1
  23
  24 #define ADC_10BIT_RANGE             0x3FF
  25 #define ADC_12BIT_RANGE             0xFFF
  26
  27 static inline int div_round_up(int x, int y) {
  28   return (x + (y - 1)) / y;
  29 }
  30
  31 static const PinMap PinMap_ADC[] = {
  32     {P0_11, ADC0_0, 0x02},
  33     {P0_12, ADC0_1, 0x02},
  34     {P0_13, ADC0_2, 0x02},
  35     {P0_14, ADC0_3, 0x02},
  36     {P0_15, ADC0_4, 0x02},
  37     {P0_16, ADC0_5, 0x01},
  38     {P0_22, ADC0_6, 0x01},
  39     {P0_23, ADC0_7, 0x01},
  40     {NC   , NC    , 0   }
  41 };
  42
  43 #define LPC_IOCON0_BASE (LPC_IOCON_BASE)
  44 #define LPC_IOCON1_BASE (LPC_IOCON_BASE + 0x60)
  45
  46 #define ADC_RANGE    ADC_10BIT_RANGE
  47
  48 void analogin_init(analogin_t *obj, PinName pin) {
  49     obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
  50     MBED_ASSERT(obj->adc != (ADCName)NC);
  51
  52     // Power up ADC
  53     LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
  54     LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
  55
  56     uint32_t pin_number = (uint32_t)pin;
  57     __IO uint32_t *reg = (pin_number < 32) ? (__IO uint32_t*)(LPC_IOCON0_BASE + 4 * pin_number) : (__IO uint32_t*)(LPC_IOCON1_BASE + 4 * (pin_number - 32));
  58
  59     // set pin to ADC mode
  60     *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
  61
  62     uint32_t PCLK = SystemCoreClock;
  63     uint32_t MAX_ADC_CLK = 4500000;
  64     uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
  65
  66     LPC_ADC->CR = (0 << 0)      // no channels selected
  67                 | (clkdiv << 8) // max of 4.5MHz
  68                 | (0 << 16)     // BURST = 0, software controlled
  69                 | ( 0 << 17 );  // CLKS = 0, not applicable
  70
  71     pinmap_pinout(pin, PinMap_ADC);
  72 }
  73
  74 static inline uint32_t adc_read(analogin_t *obj) {
  75     // Select the appropriate channel and start conversion
  76     LPC_ADC->CR &= ~0xFF;
  77     LPC_ADC->CR |= 1 << (int)obj->adc;
  78     LPC_ADC->CR |= 1 << 24;
  79
  80     // Repeatedly get the sample data until DONE bit
  81     unsigned int data;
  82     do {
  83         data = LPC_ADC->GDR;
  84     } while ((data & ((unsigned int)1 << 31)) == 0);
  85
  86     // Stop conversion
  87     LPC_ADC->CR &= ~(1 << 24);
  88
  89     return (data >> 6) & ADC_RANGE; // 10 bit
  90 }
  91
  92 static inline void order(uint32_t *a, uint32_t *b) {
  93     if (*a > *b) {
  94         uint32_t t = *a;
  95         *a = *b;
  96         *b = t;
  97     }
  98 }
  99
 100 static inline uint32_t adc_read_u32(analogin_t *obj) {
 101     uint32_t value;
 102 #if ANALOGIN_MEDIAN_FILTER
 103     uint32_t v1 = adc_read(obj);
 104     uint32_t v2 = adc_read(obj);
 105     uint32_t v3 = adc_read(obj);
 106     order(&v1, &v2);
 107     order(&v2, &v3);
 108     order(&v1, &v2);
 109     value = v2;
 110 #else
 111     value = adc_read(obj);
 112 #endif
 113     return value;
 114 }
 115
 116 uint16_t analogin_read_u16(analogin_t *obj) {
 117     uint32_t value = adc_read_u32(obj);
 118
 119     return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
 120 }
 121
 122 float analogin_read(analogin_t *obj) {
 123     uint32_t value = adc_read_u32(obj);
 124     return (float)value * (1.0f / (float)ADC_RANGE);
 125 }