ae3f0193b8
- fixed selection of resolution - fixed result masking - fixed channel selection (and optimized it) - fixed clock prescaler calculation
113 lines
2.4 KiB
C
113 lines
2.4 KiB
C
/*
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* Copyright (C) 2015-2016 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup cpu_lpc11u34
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* @ingroup drivers_periph_adc
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* @{
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*
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* @file
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* @brief Low-level ADC driver implementation
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*
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* @author Paul Rathgeb <paul.rathgeb@skynet.be>
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*
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* @}
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*/
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#include <stdint.h>
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#include "cpu.h"
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#include "mutex.h"
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#include "assert.h"
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#include "periph/adc.h"
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#define START_CMD (0x1 << 24)
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#define DONE_BIT (0x1 << 31)
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#define RES_MASK (0xf << 17)
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#define SAMPLE_SHIFT (6)
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#define SAMPLE_MASK (0x3ff)
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/* we chose an ADC clock smaller or equal than but close to 4.5MHz (as proposed
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* in the reference manual) */
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#define CLK_DIV (((CLOCK_CORECLOCK / 45000000) & 0xff) << 8)
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/**
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* @brief Mutex to synchronize ADC access from different threads
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*/
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static mutex_t lock = MUTEX_INIT;
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static inline uint32_t *pincfg_reg(adc_t line)
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{
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int offset = (line < 6) ? (11 + line) : (16 + line);
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return ((uint32_t *)(LPC_IOCON) + offset);
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}
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static inline void prep(void)
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{
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mutex_lock(&lock);
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LPC_SYSCON->PDRUNCFG &= ~(1 << 4);
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LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 13);
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}
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static inline void done(void)
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{
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LPC_SYSCON->SYSAHBCLKCTRL &= ~(1 << 13);
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LPC_SYSCON->PDRUNCFG |= (1 << 4);
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mutex_unlock(&lock);
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}
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int adc_init(adc_t line)
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{
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uint32_t *pincfg;
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prep();
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/* configure the connected pin */
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pincfg = pincfg_reg(line);
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/* Put the pin in its ADC alternate function */
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if (line < 5) {
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*pincfg |= 2;
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}
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else {
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*pincfg |= 1;
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}
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/* Configure ADMODE in analog input */
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*pincfg &= ~(1 << 7);
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done();
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return 0;
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}
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int adc_sample(adc_t line, adc_res_t res)
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{
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int sample;
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assert(line < ADC_NUMOF);
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/* check if resolution is valid */
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if (res & ~(RES_MASK)) {
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return -1;
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}
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/* prepare the device */
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prep();
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/* start conversion */
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LPC_ADC->CR = ((1 << line) | CLK_DIV | res | START_CMD);
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/* Wait for the end of the conversion */
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while (!(LPC_ADC->DR[line] & DONE_BIT)) {}
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/* Read and return result */
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sample = ((LPC_ADC->DR[line] >> SAMPLE_SHIFT) & SAMPLE_MASK);
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done();
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return sample;
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}
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