Umar Naeem / mbed-dev

mbed library sources. Supersedes mbed-src.

Fork of mbed-dev by Umar Naeem

targets/TARGET_NXP/TARGET_LPC23XX/analogin_api.c@165:2dd56e6daeec, 2017-05-23 (annotated)

Committer:
ranaumarnaeem
Date:
Tue May 23 12:54:50 2017 +0000
Revision:
165:2dd56e6daeec
Parent:
149:156823d33999 
jhjg

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /* mbed Microcontroller Library
<> 144:ef7eb2e8f9f7 2 * Copyright (c) 2006-2013 ARM Limited
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Licensed under the Apache License, Version 2.0 (the "License");
<> 144:ef7eb2e8f9f7 5 * you may not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 6 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 11 * distributed under the License is distributed on an "AS IS" BASIS,
<> 144:ef7eb2e8f9f7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 13 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 14 * limitations under the License.
<> 144:ef7eb2e8f9f7 15 */
<> 144:ef7eb2e8f9f7 16 #include "mbed_assert.h"
<> 144:ef7eb2e8f9f7 17 #include "analogin_api.h"
<> 144:ef7eb2e8f9f7 18 #include "cmsis.h"
<> 144:ef7eb2e8f9f7 19 #include "pinmap.h"
<> 144:ef7eb2e8f9f7 20
<> 144:ef7eb2e8f9f7 21 #define ANALOGIN_MEDIAN_FILTER 1
<> 144:ef7eb2e8f9f7 22
<> 144:ef7eb2e8f9f7 23 #define ADC_10BIT_RANGE 0x3FF
<> 144:ef7eb2e8f9f7 24 #define ADC_12BIT_RANGE 0xFFF
<> 144:ef7eb2e8f9f7 25
<> 144:ef7eb2e8f9f7 26 static inline int div_round_up(int x, int y) {
<> 144:ef7eb2e8f9f7 27 return (x + (y - 1)) / y;
<> 144:ef7eb2e8f9f7 28 }
<> 144:ef7eb2e8f9f7 29
<> 144:ef7eb2e8f9f7 30 static const PinMap PinMap_ADC[] = {
<> 144:ef7eb2e8f9f7 31 {P0_23, ADC0_0, 1},
<> 144:ef7eb2e8f9f7 32 {P0_24, ADC0_1, 1},
<> 144:ef7eb2e8f9f7 33 {P0_25, ADC0_2, 1},
<> 144:ef7eb2e8f9f7 34 {P0_26, ADC0_3, 1},
<> 144:ef7eb2e8f9f7 35 {P1_30, ADC0_4, 3},
<> 144:ef7eb2e8f9f7 36 {P1_31, ADC0_5, 3},
<> 144:ef7eb2e8f9f7 37 {NC, NC, 0}
<> 144:ef7eb2e8f9f7 38 };
<> 144:ef7eb2e8f9f7 39
<> 144:ef7eb2e8f9f7 40 #define ADC_RANGE ADC_10BIT_RANGE
<> 144:ef7eb2e8f9f7 41
<> 144:ef7eb2e8f9f7 42
<> 144:ef7eb2e8f9f7 43 void analogin_init(analogin_t *obj, PinName pin) {
<> 144:ef7eb2e8f9f7 44 obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
<> 144:ef7eb2e8f9f7 45 MBED_ASSERT(obj->adc != (ADCName)NC);
<> 144:ef7eb2e8f9f7 46
<> 144:ef7eb2e8f9f7 47 // ensure power is turned on
<> 144:ef7eb2e8f9f7 48 LPC_SC->PCONP |= (1 << 12);
<> 144:ef7eb2e8f9f7 49
<> 144:ef7eb2e8f9f7 50 // set PCLK of ADC to /1
<> 144:ef7eb2e8f9f7 51 LPC_SC->PCLKSEL0 &= ~(0x3 << 24);
<> 144:ef7eb2e8f9f7 52 LPC_SC->PCLKSEL0 |= (0x1 << 24);
<> 144:ef7eb2e8f9f7 53 uint32_t PCLK = SystemCoreClock;
<> 144:ef7eb2e8f9f7 54
<> 144:ef7eb2e8f9f7 55 // calculate minimum clock divider
<> 144:ef7eb2e8f9f7 56 // clkdiv = divider - 1
<> 144:ef7eb2e8f9f7 57 uint32_t MAX_ADC_CLK = 13000000;
<> 144:ef7eb2e8f9f7 58 uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
<> 144:ef7eb2e8f9f7 59
<> 144:ef7eb2e8f9f7 60 // Set the generic software-controlled ADC settings
<> 144:ef7eb2e8f9f7 61 LPC_ADC->ADCR = (0 << 0) // SEL: 0 = no channels selected
<> 144:ef7eb2e8f9f7 62 | (clkdiv << 8) // CLKDIV: PCLK max ~= 25MHz, /25 to give safe 1MHz at fastest
<> 144:ef7eb2e8f9f7 63 | (0 << 16) // BURST: 0 = software control
<> 144:ef7eb2e8f9f7 64 | (0 << 17) // CLKS: not applicable
<> 144:ef7eb2e8f9f7 65 | (1 << 21) // PDN: 1 = operational
<> 144:ef7eb2e8f9f7 66 | (0 << 24) // START: 0 = no start
<> 144:ef7eb2e8f9f7 67 | (0 << 27); // EDGE: not applicable
<> 144:ef7eb2e8f9f7 68
<> 144:ef7eb2e8f9f7 69 pinmap_pinout(pin, PinMap_ADC);
<> 144:ef7eb2e8f9f7 70 }
<> 144:ef7eb2e8f9f7 71
<> 144:ef7eb2e8f9f7 72 static inline uint32_t adc_read(analogin_t *obj) {
<> 144:ef7eb2e8f9f7 73 // Select the appropriate channel and start conversion
<> 144:ef7eb2e8f9f7 74 LPC_ADC->ADCR &= ~0xFF;
<> 144:ef7eb2e8f9f7 75 LPC_ADC->ADCR |= 1 << (int)obj->adc;
<> 144:ef7eb2e8f9f7 76 LPC_ADC->ADCR |= 1 << 24;
<> 144:ef7eb2e8f9f7 77
<> 144:ef7eb2e8f9f7 78 // Repeatedly get the sample data until DONE bit
<> 144:ef7eb2e8f9f7 79 unsigned int data;
<> 144:ef7eb2e8f9f7 80 do {
<> 144:ef7eb2e8f9f7 81 data = LPC_ADC->ADGDR;
<> 144:ef7eb2e8f9f7 82 } while ((data & ((unsigned int)1 << 31)) == 0);
<> 144:ef7eb2e8f9f7 83
<> 144:ef7eb2e8f9f7 84 // Stop conversion
<> 144:ef7eb2e8f9f7 85 LPC_ADC->ADCR &= ~(1 << 24);
<> 144:ef7eb2e8f9f7 86
<> 144:ef7eb2e8f9f7 87 return (data >> 6) & ADC_RANGE; // 10 bit
<> 144:ef7eb2e8f9f7 88 }
<> 144:ef7eb2e8f9f7 89
<> 144:ef7eb2e8f9f7 90 static inline void order(uint32_t *a, uint32_t *b) {
<> 144:ef7eb2e8f9f7 91 if (*a > *b) {
<> 144:ef7eb2e8f9f7 92 uint32_t t = *a;
<> 144:ef7eb2e8f9f7 93 *a = *b;
<> 144:ef7eb2e8f9f7 94 *b = t;
<> 144:ef7eb2e8f9f7 95 }
<> 144:ef7eb2e8f9f7 96 }
<> 144:ef7eb2e8f9f7 97
<> 144:ef7eb2e8f9f7 98 static inline uint32_t adc_read_u32(analogin_t *obj) {
<> 144:ef7eb2e8f9f7 99 uint32_t value;
<> 144:ef7eb2e8f9f7 100 #if ANALOGIN_MEDIAN_FILTER
<> 144:ef7eb2e8f9f7 101 uint32_t v1 = adc_read(obj);
<> 144:ef7eb2e8f9f7 102 uint32_t v2 = adc_read(obj);
<> 144:ef7eb2e8f9f7 103 uint32_t v3 = adc_read(obj);
<> 144:ef7eb2e8f9f7 104 order(&v1, &v2);
<> 144:ef7eb2e8f9f7 105 order(&v2, &v3);
<> 144:ef7eb2e8f9f7 106 order(&v1, &v2);
<> 144:ef7eb2e8f9f7 107 value = v2;
<> 144:ef7eb2e8f9f7 108 #else
<> 144:ef7eb2e8f9f7 109 value = adc_read(obj);
<> 144:ef7eb2e8f9f7 110 #endif
<> 144:ef7eb2e8f9f7 111 return value;
<> 144:ef7eb2e8f9f7 112 }
<> 144:ef7eb2e8f9f7 113
<> 144:ef7eb2e8f9f7 114 uint16_t analogin_read_u16(analogin_t *obj) {
<> 144:ef7eb2e8f9f7 115 uint32_t value = adc_read_u32(obj);
<> 144:ef7eb2e8f9f7 116
<> 144:ef7eb2e8f9f7 117 return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
<> 144:ef7eb2e8f9f7 118 }
<> 144:ef7eb2e8f9f7 119
<> 144:ef7eb2e8f9f7 120 float analogin_read(analogin_t *obj) {
<> 144:ef7eb2e8f9f7 121 uint32_t value = adc_read_u32(obj);
<> 144:ef7eb2e8f9f7 122 return (float)value * (1.0f / (float)ADC_RANGE);
<> 144:ef7eb2e8f9f7 123 }