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 #define ANALOGIN_MEDIAN_FILTER 1
24 #define ADC_10BIT_RANGE 0x3FF
25 #define ADC_12BIT_RANGE 0xFFF
27 static inline int div_round_up(int x, int y) {
28 return (x + (y - 1)) / y;
31 static const PinMap PinMap_ADC[] = {
32 {P0_11, ADC0_0, 0x02},
33 {P0_12, ADC0_1, 0x02},
34 {P0_13, ADC0_2, 0x02},
35 {P0_14, ADC0_3, 0x02},
36 {P0_15, ADC0_4, 0x02},
37 {P0_16, ADC0_5, 0x01},
38 {P0_22, ADC0_6, 0x01},
39 {P0_23, ADC0_7, 0x01},
43 #define LPC_IOCON0_BASE (LPC_IOCON_BASE)
44 #define LPC_IOCON1_BASE (LPC_IOCON_BASE + 0x60)
46 #define ADC_RANGE ADC_10BIT_RANGE
48 void analogin_init(analogin_t *obj, PinName pin) {
49 obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
50 MBED_ASSERT(obj->adc != (ADCName)NC);
53 LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
54 LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
56 uint32_t pin_number = (uint32_t)pin;
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));
59 // set pin to ADC mode
60 *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
62 uint32_t PCLK = SystemCoreClock;
63 uint32_t MAX_ADC_CLK = 4500000;
64 uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
66 LPC_ADC->CR = (0 << 0) // no channels selected
67 | (clkdiv << 8) // max of 4.5MHz
68 | (0 << 16) // BURST = 0, software controlled
69 | ( 0 << 17 ); // CLKS = 0, not applicable
71 pinmap_pinout(pin, PinMap_ADC);
74 static inline uint32_t adc_read(analogin_t *obj) {
75 // Select the appropriate channel and start conversion
77 LPC_ADC->CR |= 1 << (int)obj->adc;
78 LPC_ADC->CR |= 1 << 24;
80 // Repeatedly get the sample data until DONE bit
84 } while ((data & ((unsigned int)1 << 31)) == 0);
87 LPC_ADC->CR &= ~(1 << 24);
89 return (data >> 6) & ADC_RANGE; // 10 bit
92 static inline void order(uint32_t *a, uint32_t *b) {
100 static inline uint32_t adc_read_u32(analogin_t *obj) {
102 #if ANALOGIN_MEDIAN_FILTER
103 uint32_t v1 = adc_read(obj);
104 uint32_t v2 = adc_read(obj);
105 uint32_t v3 = adc_read(obj);
111 value = adc_read(obj);
116 uint16_t analogin_read_u16(analogin_t *obj) {
117 uint32_t value = adc_read_u32(obj);
119 return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
122 float analogin_read(analogin_t *obj) {
123 uint32_t value = adc_read_u32(obj);
124 return (float)value * (1.0f / (float)ADC_RANGE);