Lee Kai Xuan / mbed-os

mbed-os

Fork of mbed-os by erkin yucel

targets/TARGET_NXP/TARGET_LPC2460/analogin_api.c@1:3deb71413561, 2017-07-20 (annotated)

Committer:
xuaner
Date:
Thu Jul 20 14:26:57 2017 +0000
Revision:
1:3deb71413561
Parent:
0:f269e3021894 
mbed_os

Who changed what in which revision?

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elessair 0:f269e3021894 1 /* mbed Microcontroller Library
elessair 0:f269e3021894 2 * Copyright (c) 2006-2015 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
elessair 0:f269e3021894 21 #define ANALOGIN_MEDIAN_FILTER 1
elessair 0:f269e3021894 22
elessair 0:f269e3021894 23 #define ADC_10BIT_RANGE 0x3FF
elessair 0:f269e3021894 24 #define ADC_12BIT_RANGE 0xFFF
elessair 0:f269e3021894 25
elessair 0:f269e3021894 26 static inline int div_round_up(int x, int y) {
elessair 0:f269e3021894 27 return (x + (y - 1)) / y;
elessair 0:f269e3021894 28 }
elessair 0:f269e3021894 29
elessair 0:f269e3021894 30 static const PinMap PinMap_ADC[] = {
elessair 0:f269e3021894 31 {P0_23, ADC0_0, 1},
elessair 0:f269e3021894 32 {P0_24, ADC0_1, 1},
elessair 0:f269e3021894 33 {P0_25, ADC0_2, 1},
elessair 0:f269e3021894 34 {P0_26, ADC0_3, 1},
elessair 0:f269e3021894 35 {P1_30, ADC0_4, 3},
elessair 0:f269e3021894 36 {P1_31, ADC0_5, 3},
elessair 0:f269e3021894 37 {P0_12, ADC0_6, 3},
elessair 0:f269e3021894 38 {P0_13, ADC0_7, 3},
elessair 0:f269e3021894 39 {NC, NC, 0}
elessair 0:f269e3021894 40 };
elessair 0:f269e3021894 41
elessair 0:f269e3021894 42 #define ADC_RANGE ADC_10BIT_RANGE
elessair 0:f269e3021894 43
elessair 0:f269e3021894 44
elessair 0:f269e3021894 45 void analogin_init(analogin_t *obj, PinName pin) {
elessair 0:f269e3021894 46 obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
elessair 0:f269e3021894 47 MBED_ASSERT(obj->adc != (ADCName)NC);
elessair 0:f269e3021894 48
elessair 0:f269e3021894 49 // ensure power is turned on
elessair 0:f269e3021894 50 LPC_SC->PCONP |= (1 << PCADC);
elessair 0:f269e3021894 51
elessair 0:f269e3021894 52 // set PCLK of ADC to /1
elessair 0:f269e3021894 53 LPC_SC->PCLKSEL0 &= ~(0x3 << 24);
elessair 0:f269e3021894 54 LPC_SC->PCLKSEL0 |= (0x1 << 24);
elessair 0:f269e3021894 55 uint32_t PCLK = SystemCoreClock;
elessair 0:f269e3021894 56
elessair 0:f269e3021894 57 // calculate minimum clock divider
elessair 0:f269e3021894 58 // clkdiv = divider - 1
elessair 0:f269e3021894 59 uint32_t MAX_ADC_CLK = 4500000;
elessair 0:f269e3021894 60 uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
elessair 0:f269e3021894 61
elessair 0:f269e3021894 62 // Set the generic software-controlled ADC settings
elessair 0:f269e3021894 63 LPC_ADC->ADCR = (0 << 0) // SEL: 0 = no channels selected
elessair 0:f269e3021894 64 | (clkdiv << 8) // CLKDIV: PCLK max ~= 25MHz, /25 to give safe 1MHz at fastest
elessair 0:f269e3021894 65 | (0 << 16) // BURST: 0 = software control
elessair 0:f269e3021894 66 | (0 << 17) // CLKS: not applicable
elessair 0:f269e3021894 67 | (1 << 21) // PDN: 1 = operational
elessair 0:f269e3021894 68 | (0 << 24) // START: 0 = no start
elessair 0:f269e3021894 69 | (0 << 27); // EDGE: 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->ADCR &= ~0xFF;
elessair 0:f269e3021894 77 LPC_ADC->ADCR |= 1 << (int)obj->adc;
elessair 0:f269e3021894 78 LPC_ADC->ADCR |= 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->ADGDR;
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->ADCR &= ~(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 }