Lee Kai Xuan / mbed-os

mbed-os

Fork of mbed-os by erkin yucel

targets/TARGET_NXP/TARGET_LPC13XX/analogin_api.c@0:f269e3021894, 2016-10-23 (annotated)

Committer:
elessair
Date:
Sun Oct 23 15:10:02 2016 +0000
Revision:
0:f269e3021894
Initial commit

Who changed what in which revision?

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elessair 0:f269e3021894 1 /* mbed Microcontroller Library
elessair 0:f269e3021894 2 * Copyright (c) 2006-2013 ARM Limited
elessair 0:f269e3021894 3 *
elessair 0:f269e3021894 4 * Licensed under the Apache License, Version 2.0 (the "License");
elessair 0:f269e3021894 5 * you may not use this file except in compliance with the License.
elessair 0:f269e3021894 6 * You may obtain a copy of the License at
elessair 0:f269e3021894 7 *
elessair 0:f269e3021894 8 * http://www.apache.org/licenses/LICENSE-2.0
elessair 0:f269e3021894 9 *
elessair 0:f269e3021894 10 * Unless required by applicable law or agreed to in writing, software
elessair 0:f269e3021894 11 * distributed under the License is distributed on an "AS IS" BASIS,
elessair 0:f269e3021894 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
elessair 0:f269e3021894 13 * See the License for the specific language governing permissions and
elessair 0:f269e3021894 14 * limitations under the License.
elessair 0:f269e3021894 15 */
elessair 0:f269e3021894 16 #include "mbed_assert.h"
elessair 0:f269e3021894 17 #include "analogin_api.h"
elessair 0:f269e3021894 18 #include "cmsis.h"
elessair 0:f269e3021894 19 #include "pinmap.h"
elessair 0:f269e3021894 20 #include "mbed_error.h"
elessair 0:f269e3021894 21
elessair 0:f269e3021894 22 #define ANALOGIN_MEDIAN_FILTER 1
elessair 0:f269e3021894 23
elessair 0:f269e3021894 24 #define ADC_10BIT_RANGE 0x3FF
elessair 0:f269e3021894 25 #define ADC_12BIT_RANGE 0xFFF
elessair 0:f269e3021894 26
elessair 0:f269e3021894 27 static inline int div_round_up(int x, int y) {
elessair 0:f269e3021894 28 return (x + (y - 1)) / y;
elessair 0:f269e3021894 29 }
elessair 0:f269e3021894 30
elessair 0:f269e3021894 31 static const PinMap PinMap_ADC[] = {
elessair 0:f269e3021894 32 {P0_11, ADC0_0, 0x02},
elessair 0:f269e3021894 33 {P0_12, ADC0_1, 0x02},
elessair 0:f269e3021894 34 {P0_13, ADC0_2, 0x02},
elessair 0:f269e3021894 35 {P0_14, ADC0_3, 0x02},
elessair 0:f269e3021894 36 {P0_15, ADC0_4, 0x02},
elessair 0:f269e3021894 37 {P0_16, ADC0_5, 0x01},
elessair 0:f269e3021894 38 {P0_22, ADC0_6, 0x01},
elessair 0:f269e3021894 39 {P0_23, ADC0_7, 0x01},
elessair 0:f269e3021894 40 {NC , NC , 0 }
elessair 0:f269e3021894 41 };
elessair 0:f269e3021894 42
elessair 0:f269e3021894 43 #define LPC_IOCON0_BASE (LPC_IOCON_BASE)
elessair 0:f269e3021894 44 #define LPC_IOCON1_BASE (LPC_IOCON_BASE + 0x60)
elessair 0:f269e3021894 45
elessair 0:f269e3021894 46 #define ADC_RANGE ADC_10BIT_RANGE
elessair 0:f269e3021894 47
elessair 0:f269e3021894 48 void analogin_init(analogin_t *obj, PinName pin) {
elessair 0:f269e3021894 49 obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
elessair 0:f269e3021894 50 MBED_ASSERT(obj->adc != (ADCName)NC);
elessair 0:f269e3021894 51
elessair 0:f269e3021894 52 // Power up ADC
elessair 0:f269e3021894 53 LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
elessair 0:f269e3021894 54 LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
elessair 0:f269e3021894 55
elessair 0:f269e3021894 56 uint32_t pin_number = (uint32_t)pin;
elessair 0:f269e3021894 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));
elessair 0:f269e3021894 58
elessair 0:f269e3021894 59 // set pin to ADC mode
elessair 0:f269e3021894 60 *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
elessair 0:f269e3021894 61
elessair 0:f269e3021894 62 uint32_t PCLK = SystemCoreClock;
elessair 0:f269e3021894 63 uint32_t MAX_ADC_CLK = 4500000;
elessair 0:f269e3021894 64 uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
elessair 0:f269e3021894 65
elessair 0:f269e3021894 66 LPC_ADC->CR = (0 << 0) // no channels selected
elessair 0:f269e3021894 67 | (clkdiv << 8) // max of 4.5MHz
elessair 0:f269e3021894 68 | (0 << 16) // BURST = 0, software controlled
elessair 0:f269e3021894 69 | ( 0 << 17 ); // CLKS = 0, not applicable
elessair 0:f269e3021894 70
elessair 0:f269e3021894 71 pinmap_pinout(pin, PinMap_ADC);
elessair 0:f269e3021894 72 }
elessair 0:f269e3021894 73
elessair 0:f269e3021894 74 static inline uint32_t adc_read(analogin_t *obj) {
elessair 0:f269e3021894 75 // Select the appropriate channel and start conversion
elessair 0:f269e3021894 76 LPC_ADC->CR &= ~0xFF;
elessair 0:f269e3021894 77 LPC_ADC->CR |= 1 << (int)obj->adc;
elessair 0:f269e3021894 78 LPC_ADC->CR |= 1 << 24;
elessair 0:f269e3021894 79
elessair 0:f269e3021894 80 // Repeatedly get the sample data until DONE bit
elessair 0:f269e3021894 81 unsigned int data;
elessair 0:f269e3021894 82 do {
elessair 0:f269e3021894 83 data = LPC_ADC->GDR;
elessair 0:f269e3021894 84 } while ((data & ((unsigned int)1 << 31)) == 0);
elessair 0:f269e3021894 85
elessair 0:f269e3021894 86 // Stop conversion
elessair 0:f269e3021894 87 LPC_ADC->CR &= ~(1 << 24);
elessair 0:f269e3021894 88
elessair 0:f269e3021894 89 return (data >> 6) & ADC_RANGE; // 10 bit
elessair 0:f269e3021894 90 }
elessair 0:f269e3021894 91
elessair 0:f269e3021894 92 static inline void order(uint32_t *a, uint32_t *b) {
elessair 0:f269e3021894 93 if (*a > *b) {
elessair 0:f269e3021894 94 uint32_t t = *a;
elessair 0:f269e3021894 95 *a = *b;
elessair 0:f269e3021894 96 *b = t;
elessair 0:f269e3021894 97 }
elessair 0:f269e3021894 98 }
elessair 0:f269e3021894 99
elessair 0:f269e3021894 100 static inline uint32_t adc_read_u32(analogin_t *obj) {
elessair 0:f269e3021894 101 uint32_t value;
elessair 0:f269e3021894 102 #if ANALOGIN_MEDIAN_FILTER
elessair 0:f269e3021894 103 uint32_t v1 = adc_read(obj);
elessair 0:f269e3021894 104 uint32_t v2 = adc_read(obj);
elessair 0:f269e3021894 105 uint32_t v3 = adc_read(obj);
elessair 0:f269e3021894 106 order(&v1, &v2);
elessair 0:f269e3021894 107 order(&v2, &v3);
elessair 0:f269e3021894 108 order(&v1, &v2);
elessair 0:f269e3021894 109 value = v2;
elessair 0:f269e3021894 110 #else
elessair 0:f269e3021894 111 value = adc_read(obj);
elessair 0:f269e3021894 112 #endif
elessair 0:f269e3021894 113 return value;
elessair 0:f269e3021894 114 }
elessair 0:f269e3021894 115
elessair 0:f269e3021894 116 uint16_t analogin_read_u16(analogin_t *obj) {
elessair 0:f269e3021894 117 uint32_t value = adc_read_u32(obj);
elessair 0:f269e3021894 118
elessair 0:f269e3021894 119 return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
elessair 0:f269e3021894 120 }
elessair 0:f269e3021894 121
elessair 0:f269e3021894 122 float analogin_read(analogin_t *obj) {
elessair 0:f269e3021894 123 uint32_t value = adc_read_u32(obj);
elessair 0:f269e3021894 124 return (float)value * (1.0f / (float)ADC_RANGE);
elessair 0:f269e3021894 125 }