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 "PeripheralNames.h"
24 #define ANALOGIN_MEDIAN_FILTER 1
26 #define ADC_RANGE 0xFFF
28 static const PinMap PinMap_ADC[] = {
43 void analogin_init(analogin_t *obj, PinName pin)
45 obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
46 MBED_ASSERT(obj->adc != (ADCName)NC);
48 LPC_SYSCON->SYSAHBCLKCTRL |= (1UL << 6);
50 LPC_SWM->PINENABLE0 &= ~(1UL << (13 + obj->adc));
51 // configure GPIO as input
52 LPC_GPIO_PORT->DIR0 &= ~(1UL << (pin >> PIN_SHIFT));
54 LPC_SYSCON->PDRUNCFG &= ~(1 << 4);
55 LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 24);
57 __IO LPC_ADC_Type *adc_reg = LPC_ADC;
59 // determine the system clock divider for a 500kHz ADC clock during calibration
60 uint32_t clkdiv = (SystemCoreClock / 500000) - 1;
62 // perform a self-calibration
63 adc_reg->CTRL = (1UL << 30) | (clkdiv & 0xFF);
64 while ((adc_reg->CTRL & (1UL << 30)) != 0);
67 static inline uint32_t adc_read(analogin_t *obj)
70 __IO LPC_ADC_Type *adc_reg = LPC_ADC;
72 channels = (obj->adc & 0x1F);
75 adc_reg->SEQA_CTRL &= ~(0xFFF);
76 adc_reg->SEQA_CTRL |= (1UL << channels);
78 // start conversion and sequence enable
79 adc_reg->SEQA_CTRL |= ((1UL << 26) | (1UL << 31));
81 // Repeatedly get the sample data until DONE bit
82 volatile uint32_t data;
84 data = adc_reg->SEQA_GDAT;
85 } while ((data & (1UL << 31)) == 0);
88 adc_reg->SEQA_CTRL &= ~(1UL << 31);
90 return ((data >> 4) & ADC_RANGE);
93 static inline void order(uint32_t *a, uint32_t *b)
102 static inline uint32_t adc_read_u32(analogin_t *obj)
105 #if ANALOGIN_MEDIAN_FILTER
106 uint32_t v1 = adc_read(obj);
107 uint32_t v2 = adc_read(obj);
108 uint32_t v3 = adc_read(obj);
114 value = adc_read(obj);
119 uint16_t analogin_read_u16(analogin_t *obj)
121 uint32_t value = adc_read_u32(obj);
122 return (value << 4) | ((value >> 8) & 0x000F); // 12 bit
125 float analogin_read(analogin_t *obj)
127 uint32_t value = adc_read_u32(obj);
128 return (float)value * (1.0f / (float)ADC_RANGE);