128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/* mbed Microcontroller Library
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* Copyright (c) 2006-2013 ARM Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "mbed_assert.h"
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#include "analogin_api.h"
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#include "cmsis.h"
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#include "pinmap.h"
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#include "mbed_error.h"
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static const PinMap PinMap_ADC[] = {
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{P0_11, ADC0_0, 2},
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{P1_0 , ADC0_1, 2},
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{P1_1 , ADC0_2, 2},
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{P1_2 , ADC0_3, 2},
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// {P1_3 , ADC0_4, 2}, -- should be mapped to SWDIO only
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{P1_4 , ADC0_5, 1},
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{P1_10, ADC0_6, 1},
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{P1_11, ADC0_7, 1},
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{NC , NC , 0}
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};
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#define ANALOGIN_MEDIAN_FILTER 1
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#define ADC_10BIT_RANGE 0x3FF
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#define ADC_12BIT_RANGE 0xFFF
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static inline int div_round_up(int x, int y) {
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return (x + (y - 1)) / y;
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}
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#define ADC_RANGE ADC_10BIT_RANGE
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void analogin_init(analogin_t *obj, PinName pin) {
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obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
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MBED_ASSERT(obj->adc != (ADCName)NC);
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// Power up ADC
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LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
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LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
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uint32_t offset = (uint32_t)pin & 0xff;
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__IO uint32_t *reg = (__IO uint32_t*)(LPC_IOCON_BASE + offset);
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// set pin to ADC mode
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*reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
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uint32_t PCLK = SystemCoreClock;
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uint32_t MAX_ADC_CLK = 4500000;
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uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
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LPC_ADC->CR = (0 << 0) // no channels selected
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| (clkdiv << 8) // max of 4.5MHz
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| (0 << 16) // BURST = 0, software controlled
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| ( 0 << 17 ); // CLKS = 0, not applicable
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pinmap_pinout(pin, PinMap_ADC);
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}
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static inline uint32_t adc_read(analogin_t *obj) {
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// Select the appropriate channel and start conversion
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LPC_ADC->CR &= ~0xFF;
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LPC_ADC->CR |= 1 << (int)obj->adc;
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LPC_ADC->CR |= 1 << 24;
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// Repeatedly get the sample data until DONE bit
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unsigned int data;
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do {
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data = LPC_ADC->GDR;
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} while ((data & ((unsigned int)1 << 31)) == 0);
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// Stop conversion
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LPC_ADC->CR &= ~(1 << 24);
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return (data >> 6) & ADC_RANGE; // 10 bit
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}
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static inline void order(uint32_t *a, uint32_t *b) {
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if (*a > *b) {
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uint32_t t = *a;
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*a = *b;
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*b = t;
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}
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}
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static inline uint32_t adc_read_u32(analogin_t *obj) {
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uint32_t value;
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#if ANALOGIN_MEDIAN_FILTER
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uint32_t v1 = adc_read(obj);
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uint32_t v2 = adc_read(obj);
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uint32_t v3 = adc_read(obj);
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order(&v1, &v2);
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order(&v2, &v3);
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order(&v1, &v2);
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value = v2;
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#else
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value = adc_read(obj);
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#endif
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return value;
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}
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uint16_t analogin_read_u16(analogin_t *obj) {
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uint32_t value = adc_read_u32(obj);
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return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
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}
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float analogin_read(analogin_t *obj) {
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uint32_t value = adc_read_u32(obj);
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return (float)value * (1.0f / (float)ADC_RANGE);
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}
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const PinMap *analogin_pinmap()
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{
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return PinMap_ADC;
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}
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