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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 "PeripheralNames.h"
#if DEVICE_ANALOGIN
#define ANALOGIN_MEDIAN_FILTER 1
#define ADC_RANGE 0xFFF
static const PinMap PinMap_ADC[] = {
{P0_7 , ADC_0, 0},
{P0_6 , ADC_1, 0},
{P0_14, ADC_2, 0},
{P0_23, ADC_3, 0},
{P0_22, ADC_4, 0},
{P0_21, ADC_5, 0},
{P0_20, ADC_6, 0},
{P0_19, ADC_7, 0},
{P0_18, ADC_8, 0},
{P0_17, ADC_9, 0},
{P0_13, ADC_10,0},
{P0_4 , ADC_11,0},
};
void analogin_init(analogin_t *obj, PinName pin)
{
obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
MBED_ASSERT(obj->adc != (ADCName)NC);
LPC_SYSCON->SYSAHBCLKCTRL |= (1UL << 6);
// pin enable
LPC_SWM->PINENABLE0 &= ~(1UL << (13 + obj->adc));
// configure GPIO as input
LPC_GPIO_PORT->DIR0 &= ~(1UL << (pin >> PIN_SHIFT));
LPC_SYSCON->PDRUNCFG &= ~(1 << 4);
LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 24);
__IO LPC_ADC_Type *adc_reg = LPC_ADC;
// determine the system clock divider for a 500kHz ADC clock during calibration
uint32_t clkdiv = (SystemCoreClock / 500000) - 1;
// perform a self-calibration
adc_reg->CTRL = (1UL << 30) | (clkdiv & 0xFF);
while ((adc_reg->CTRL & (1UL << 30)) != 0);
}
static inline uint32_t adc_read(analogin_t *obj)
{
uint32_t channels;
__IO LPC_ADC_Type *adc_reg = LPC_ADC;
channels = (obj->adc & 0x1F);
// select channel
adc_reg->SEQA_CTRL &= ~(0xFFF);
adc_reg->SEQA_CTRL |= (1UL << channels);
// start conversion and sequence enable
adc_reg->SEQA_CTRL |= ((1UL << 26) | (1UL << 31));
// Repeatedly get the sample data until DONE bit
volatile uint32_t data;
do {
data = adc_reg->SEQA_GDAT;
} while ((data & (1UL << 31)) == 0);
// Stop conversion
adc_reg->SEQA_CTRL &= ~(1UL << 31);
return ((data >> 4) & ADC_RANGE);
}
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);
}
#endif
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