Joris Aerts / mbed-src

mbed library sources

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targets/hal/TARGET_NXP/TARGET_LPC176X/analogin_api.c@19:398f4c622e1b, 2013-08-19 (annotated)

Committer:
bogdanm
Date:
Mon Aug 19 18:17:02 2013 +0300
Revision:
19:398f4c622e1b
Parent:
13:0645d8841f51
Child:
227:7bd0639b8911
Sync with official mbed library release 66

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 10:3bc89ef62ce7 1 /* mbed Microcontroller Library
emilmont 10:3bc89ef62ce7 2 * Copyright (c) 2006-2013 ARM Limited
emilmont 10:3bc89ef62ce7 3 *
emilmont 10:3bc89ef62ce7 4 * Licensed under the Apache License, Version 2.0 (the "License");
emilmont 10:3bc89ef62ce7 5 * you may not use this file except in compliance with the License.
emilmont 10:3bc89ef62ce7 6 * You may obtain a copy of the License at
emilmont 10:3bc89ef62ce7 7 *
emilmont 10:3bc89ef62ce7 8 * http://www.apache.org/licenses/LICENSE-2.0
emilmont 10:3bc89ef62ce7 9 *
emilmont 10:3bc89ef62ce7 10 * Unless required by applicable law or agreed to in writing, software
emilmont 10:3bc89ef62ce7 11 * distributed under the License is distributed on an "AS IS" BASIS,
emilmont 10:3bc89ef62ce7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
emilmont 10:3bc89ef62ce7 13 * See the License for the specific language governing permissions and
emilmont 10:3bc89ef62ce7 14 * limitations under the License.
emilmont 10:3bc89ef62ce7 15 */
emilmont 10:3bc89ef62ce7 16 #include "analogin_api.h"
emilmont 10:3bc89ef62ce7 17
emilmont 10:3bc89ef62ce7 18 #include "cmsis.h"
emilmont 10:3bc89ef62ce7 19 #include "pinmap.h"
emilmont 10:3bc89ef62ce7 20 #include "error.h"
emilmont 10:3bc89ef62ce7 21
emilmont 10:3bc89ef62ce7 22 #define ANALOGIN_MEDIAN_FILTER 1
emilmont 10:3bc89ef62ce7 23
emilmont 10:3bc89ef62ce7 24 #define ADC_10BIT_RANGE 0x3FF
emilmont 10:3bc89ef62ce7 25 #define ADC_12BIT_RANGE 0xFFF
emilmont 10:3bc89ef62ce7 26
emilmont 10:3bc89ef62ce7 27 static inline int div_round_up(int x, int y) {
emilmont 10:3bc89ef62ce7 28 return (x + (y - 1)) / y;
emilmont 10:3bc89ef62ce7 29 }
emilmont 10:3bc89ef62ce7 30
emilmont 10:3bc89ef62ce7 31 static const PinMap PinMap_ADC[] = {
emilmont 10:3bc89ef62ce7 32 {P0_23, ADC0_0, 1},
emilmont 10:3bc89ef62ce7 33 {P0_24, ADC0_1, 1},
emilmont 10:3bc89ef62ce7 34 {P0_25, ADC0_2, 1},
emilmont 10:3bc89ef62ce7 35 {P0_26, ADC0_3, 1},
emilmont 10:3bc89ef62ce7 36 {P1_30, ADC0_4, 3},
emilmont 10:3bc89ef62ce7 37 {P1_31, ADC0_5, 3},
emilmont 10:3bc89ef62ce7 38 {P0_2, ADC0_7, 2},
emilmont 10:3bc89ef62ce7 39 {P0_3, ADC0_6, 2},
emilmont 10:3bc89ef62ce7 40 {NC, NC, 0}
emilmont 10:3bc89ef62ce7 41 };
emilmont 10:3bc89ef62ce7 42
emilmont 10:3bc89ef62ce7 43 #define ADC_RANGE ADC_12BIT_RANGE
emilmont 10:3bc89ef62ce7 44
emilmont 10:3bc89ef62ce7 45 void analogin_init(analogin_t *obj, PinName pin) {
emilmont 10:3bc89ef62ce7 46 obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
bogdanm 19:398f4c622e1b 47 if (obj->adc == (ADCName)NC) {
emilmont 10:3bc89ef62ce7 48 error("ADC pin mapping failed");
emilmont 10:3bc89ef62ce7 49 }
emilmont 10:3bc89ef62ce7 50
emilmont 10:3bc89ef62ce7 51 // ensure power is turned on
emilmont 10:3bc89ef62ce7 52 LPC_SC->PCONP |= (1 << 12);
emilmont 10:3bc89ef62ce7 53
emilmont 10:3bc89ef62ce7 54 // set PCLK of ADC to /1
emilmont 10:3bc89ef62ce7 55 LPC_SC->PCLKSEL0 &= ~(0x3 << 24);
emilmont 10:3bc89ef62ce7 56 LPC_SC->PCLKSEL0 |= (0x1 << 24);
emilmont 10:3bc89ef62ce7 57 uint32_t PCLK = SystemCoreClock;
emilmont 10:3bc89ef62ce7 58
emilmont 10:3bc89ef62ce7 59 // calculate minimum clock divider
emilmont 10:3bc89ef62ce7 60 // clkdiv = divider - 1
emilmont 10:3bc89ef62ce7 61 uint32_t MAX_ADC_CLK = 13000000;
emilmont 10:3bc89ef62ce7 62 uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
emilmont 10:3bc89ef62ce7 63
emilmont 10:3bc89ef62ce7 64 // Set the generic software-controlled ADC settings
emilmont 10:3bc89ef62ce7 65 LPC_ADC->ADCR = (0 << 0) // SEL: 0 = no channels selected
emilmont 10:3bc89ef62ce7 66 | (clkdiv << 8) // CLKDIV: PCLK max ~= 25MHz, /25 to give safe 1MHz at fastest
emilmont 10:3bc89ef62ce7 67 | (0 << 16) // BURST: 0 = software control
emilmont 10:3bc89ef62ce7 68 | (0 << 17) // CLKS: not applicable
emilmont 10:3bc89ef62ce7 69 | (1 << 21) // PDN: 1 = operational
emilmont 10:3bc89ef62ce7 70 | (0 << 24) // START: 0 = no start
emilmont 10:3bc89ef62ce7 71 | (0 << 27); // EDGE: not applicable
emilmont 10:3bc89ef62ce7 72
emilmont 10:3bc89ef62ce7 73 pinmap_pinout(pin, PinMap_ADC);
emilmont 10:3bc89ef62ce7 74 }
emilmont 10:3bc89ef62ce7 75
emilmont 10:3bc89ef62ce7 76 static inline uint32_t adc_read(analogin_t *obj) {
emilmont 10:3bc89ef62ce7 77 // Select the appropriate channel and start conversion
emilmont 10:3bc89ef62ce7 78 LPC_ADC->ADCR &= ~0xFF;
emilmont 10:3bc89ef62ce7 79 LPC_ADC->ADCR |= 1 << (int)obj->adc;
emilmont 10:3bc89ef62ce7 80 LPC_ADC->ADCR |= 1 << 24;
emilmont 10:3bc89ef62ce7 81
emilmont 10:3bc89ef62ce7 82 // Repeatedly get the sample data until DONE bit
emilmont 10:3bc89ef62ce7 83 unsigned int data;
emilmont 10:3bc89ef62ce7 84 do {
emilmont 10:3bc89ef62ce7 85 data = LPC_ADC->ADGDR;
emilmont 10:3bc89ef62ce7 86 } while ((data & ((unsigned int)1 << 31)) == 0);
emilmont 10:3bc89ef62ce7 87
emilmont 10:3bc89ef62ce7 88 // Stop conversion
emilmont 10:3bc89ef62ce7 89 LPC_ADC->ADCR &= ~(1 << 24);
emilmont 10:3bc89ef62ce7 90
emilmont 10:3bc89ef62ce7 91 return (data >> 4) & ADC_RANGE; // 12 bit
emilmont 10:3bc89ef62ce7 92 }
emilmont 10:3bc89ef62ce7 93
emilmont 10:3bc89ef62ce7 94 static inline void order(uint32_t *a, uint32_t *b) {
emilmont 10:3bc89ef62ce7 95 if (*a > *b) {
emilmont 10:3bc89ef62ce7 96 uint32_t t = *a;
emilmont 10:3bc89ef62ce7 97 *a = *b;
emilmont 10:3bc89ef62ce7 98 *b = t;
emilmont 10:3bc89ef62ce7 99 }
emilmont 10:3bc89ef62ce7 100 }
emilmont 10:3bc89ef62ce7 101
emilmont 10:3bc89ef62ce7 102 static inline uint32_t adc_read_u32(analogin_t *obj) {
emilmont 10:3bc89ef62ce7 103 uint32_t value;
emilmont 10:3bc89ef62ce7 104 #if ANALOGIN_MEDIAN_FILTER
emilmont 10:3bc89ef62ce7 105 uint32_t v1 = adc_read(obj);
emilmont 10:3bc89ef62ce7 106 uint32_t v2 = adc_read(obj);
emilmont 10:3bc89ef62ce7 107 uint32_t v3 = adc_read(obj);
emilmont 10:3bc89ef62ce7 108 order(&v1, &v2);
emilmont 10:3bc89ef62ce7 109 order(&v2, &v3);
emilmont 10:3bc89ef62ce7 110 order(&v1, &v2);
emilmont 10:3bc89ef62ce7 111 value = v2;
emilmont 10:3bc89ef62ce7 112 #else
emilmont 10:3bc89ef62ce7 113 value = adc_read(obj);
emilmont 10:3bc89ef62ce7 114 #endif
emilmont 10:3bc89ef62ce7 115 return value;
emilmont 10:3bc89ef62ce7 116 }
emilmont 10:3bc89ef62ce7 117
emilmont 10:3bc89ef62ce7 118 uint16_t analogin_read_u16(analogin_t *obj) {
emilmont 10:3bc89ef62ce7 119 uint32_t value = adc_read_u32(obj);
emilmont 10:3bc89ef62ce7 120
emilmont 10:3bc89ef62ce7 121 return (value << 4) | ((value >> 8) & 0x000F); // 12 bit
emilmont 10:3bc89ef62ce7 122 }
emilmont 10:3bc89ef62ce7 123
emilmont 10:3bc89ef62ce7 124 float analogin_read(analogin_t *obj) {
emilmont 10:3bc89ef62ce7 125 uint32_t value = adc_read_u32(obj);
emilmont 10:3bc89ef62ce7 126 return (float)value * (1.0f / (float)ADC_RANGE);
emilmont 10:3bc89ef62ce7 127 }