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/* mbed Microcontroller Library
* Copyright (c) 2006-2013 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mbed_assert.h"
#include "analogin_api.h"
#include "cmsis.h"
#include "pinmap.h"
#include "mbed_error.h"
#define ANALOGIN_MEDIAN_FILTER 1
#define ADC_10BIT_RANGE 0x3FF
#define ADC_12BIT_RANGE 0xFFF
static inline int div_round_up(int x, int y) {
return (x + (y - 1)) / y;
}
static const PinMap PinMap_ADC[] = {
{P0_25, ADC0_2, 0x01},
{P0_26, ADC0_3, 0x01},
{NC , NC , 0 }
};
#define ADC_RANGE ADC_12BIT_RANGE
void analogin_init(analogin_t *obj, PinName pin) {
obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
MBED_ASSERT(obj->adc != (ADCName)NC);
// ensure power is turned on
LPC_SC->PCONP |= (1 << 12);
uint32_t PCLK = PeripheralClock;
// calculate minimum clock divider
// clkdiv = divider - 1
uint32_t MAX_ADC_CLK = 12400000;
uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
// Set the generic software-controlled ADC settings
LPC_ADC->CR = (0 << 0) // SEL: 0 = no channels selected
| (clkdiv << 8) // CLKDIV:
| (0 << 16) // BURST: 0 = software control
| (1 << 21) // PDN: 1 = operational
| (0 << 24) // START: 0 = no start
| (0 << 27); // EDGE: not applicable
// must enable analog mode (ADMODE = 0)
__IO uint32_t *reg = (__IO uint32_t*) (LPC_IOCON_BASE + 4 * pin);
*reg &= ~(1 << 7);
pinmap_pinout(pin, PinMap_ADC);
}
static inline uint32_t adc_read(analogin_t *obj) {
// Select the appropriate channel and start conversion
LPC_ADC->CR &= ~0xFF;
LPC_ADC->CR |= 1 << (int)obj->adc;
LPC_ADC->CR |= 1 << 24;
// Repeatedly get the sample data until DONE bit
unsigned int data;
do {
data = LPC_ADC->GDR;
} while ((data & ((unsigned int)1 << 31)) == 0);
// Stop conversion
LPC_ADC->CR &= ~(1 << 24);
return (data >> 4) & ADC_RANGE; // 12 bit
}
static inline void order(uint32_t *a, uint32_t *b) {
if (*a > *b) {
uint32_t t = *a;
*a = *b;
*b = t;
}
}
static inline uint32_t adc_read_u32(analogin_t *obj) {
uint32_t value;
#if ANALOGIN_MEDIAN_FILTER
uint32_t v1 = adc_read(obj);
uint32_t v2 = adc_read(obj);
uint32_t v3 = adc_read(obj);
order(&v1, &v2);
order(&v2, &v3);
order(&v1, &v2);
value = v2;
#else
value = adc_read(obj);
#endif
return value;
}
uint16_t analogin_read_u16(analogin_t *obj) {
uint32_t value = adc_read_u32(obj);
return (value << 4) | ((value >> 8) & 0x000F); // 12 bit
}
float analogin_read(analogin_t *obj) {
uint32_t value = adc_read_u32(obj);
return (float)value * (1.0f / (float)ADC_RANGE);
}
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