1 /* mbed Microcontroller Library
2 * Copyright (c) 2006-2013 ARM Limited
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
16 #include "mbed_assert.h"
17 #include "analogin_api.h"
20 #include "mbed_error.h"
22 static const PinMap PinMap_ADC[] = {
27 // {P1_3 , ADC0_4, 2}, -- should be mapped to SWDIO only
34 #define ANALOGIN_MEDIAN_FILTER 1
36 #define ADC_10BIT_RANGE 0x3FF
37 #define ADC_12BIT_RANGE 0xFFF
39 static inline int div_round_up(int x, int y) {
40 return (x + (y - 1)) / y;
43 #define ADC_RANGE ADC_10BIT_RANGE
45 void analogin_init(analogin_t *obj, PinName pin) {
46 obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
47 MBED_ASSERT(obj->adc != (uint32_t)NC);
50 LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
51 LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
53 uint32_t offset = (uint32_t)pin & 0xff;
54 __IO uint32_t *reg = (__IO uint32_t*)(LPC_IOCON_BASE + offset);
56 // set pin to ADC mode
57 *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
59 uint32_t PCLK = SystemCoreClock;
60 uint32_t MAX_ADC_CLK = 4500000;
61 uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
63 LPC_ADC->CR = (0 << 0) // no channels selected
64 | (clkdiv << 8) // max of 4.5MHz
65 | (0 << 16) // BURST = 0, software controlled
66 | ( 0 << 17 ); // CLKS = 0, not applicable
68 pinmap_pinout(pin, PinMap_ADC);
71 static inline uint32_t adc_read(analogin_t *obj) {
72 // Select the appropriate channel and start conversion
74 LPC_ADC->CR |= 1 << (int)obj->adc;
75 LPC_ADC->CR |= 1 << 24;
77 // Repeatedly get the sample data until DONE bit
81 } while ((data & ((unsigned int)1 << 31)) == 0);
84 LPC_ADC->CR &= ~(1 << 24);
86 return (data >> 6) & ADC_RANGE; // 10 bit
89 static inline void order(uint32_t *a, uint32_t *b) {
97 static inline uint32_t adc_read_u32(analogin_t *obj) {
99 #if ANALOGIN_MEDIAN_FILTER
100 uint32_t v1 = adc_read(obj);
101 uint32_t v2 = adc_read(obj);
102 uint32_t v3 = adc_read(obj);
108 value = adc_read(obj);
113 uint16_t analogin_read_u16(analogin_t *obj) {
114 uint32_t value = adc_read_u32(obj);
116 return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
119 float analogin_read(analogin_t *obj) {
120 uint32_t value = adc_read_u32(obj);
121 return (float)value * (1.0f / (float)ADC_RANGE);