tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/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 #include "PeripheralPins.h" // For the Peripheral to Pin Definitions found in the individual Target's Platform
  22
  23 #define ANALOGIN_MEDIAN_FILTER      1
  24
  25 #define ADC_10BIT_RANGE             0x3FF
  26 #define ADC_12BIT_RANGE             0xFFF
  27
  28 static inline int div_round_up(int x, int y) {
  29   return (x + (y - 1)) / y;
  30 }
  31
  32 #define LPC_IOCON0_BASE (LPC_IOCON_BASE)
  33 #define LPC_IOCON1_BASE (LPC_IOCON_BASE + 0x60)
  34
  35 #define ADC_RANGE    ADC_10BIT_RANGE
  36
  37 void analogin_init(analogin_t *obj, PinName pin) {
  38     obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
  39     MBED_ASSERT(obj->adc != (ADCName)NC);
  40
  41     // Power up ADC
  42     LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
  43     LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
  44
  45     uint32_t pin_number = (uint32_t)pin;
  46     __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));
  47
  48     // set pin to ADC mode
  49     *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
  50
  51     uint32_t PCLK = SystemCoreClock;
  52     uint32_t MAX_ADC_CLK = 4500000;
  53     uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
  54
  55     LPC_ADC->CR = (0 << 0)      // no channels selected
  56                 | (clkdiv << 8) // max of 4.5MHz
  57                 | (0 << 16)     // BURST = 0, software controlled
  58                 | ( 0 << 17 );  // CLKS = 0, not applicable
  59
  60     pinmap_pinout(pin, PinMap_ADC);
  61 }
  62
  63 static inline uint32_t adc_read(analogin_t *obj) {
  64     // Select the appropriate channel and start conversion
  65     LPC_ADC->CR &= ~0xFF;
  66     LPC_ADC->CR |= 1 << (int)obj->adc;
  67     LPC_ADC->CR |= 1 << 24;
  68
  69     // Repeatedly get the sample data until DONE bit
  70     unsigned int data;
  71     do {
  72         data = LPC_ADC->GDR;
  73     } while ((data & ((unsigned int)1 << 31)) == 0);
  74
  75     // Stop conversion
  76     LPC_ADC->CR &= ~(1 << 24);
  77
  78     return (data >> 6) & ADC_RANGE; // 10 bit
  79 }
  80
  81 static inline void order(uint32_t *a, uint32_t *b) {
  82     if (*a > *b) {
  83         uint32_t t = *a;
  84         *a = *b;
  85         *b = t;
  86     }
  87 }
  88
  89 static inline uint32_t adc_read_u32(analogin_t *obj) {
  90     uint32_t value;
  91 #if ANALOGIN_MEDIAN_FILTER
  92     uint32_t v1 = adc_read(obj);
  93     uint32_t v2 = adc_read(obj);
  94     uint32_t v3 = adc_read(obj);
  95     order(&v1, &v2);
  96     order(&v2, &v3);
  97     order(&v1, &v2);
  98     value = v2;
  99 #else
 100     value = adc_read(obj);
 101 #endif
 102     return value;
 103 }
 104
 105 uint16_t analogin_read_u16(analogin_t *obj) {
 106     uint32_t value = adc_read_u32(obj);
 107
 108     return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
 109 }
 110
 111 float analogin_read(analogin_t *obj) {
 112     uint32_t value = adc_read_u32(obj);
 113     return (float)value * (1.0f / (float)ADC_RANGE);
 114 }