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104 lines
2.0 KiB
C
104 lines
2.0 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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* @{
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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 "periph/adc.h"
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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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/* ADC frequency : 3MHz */
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LPC_ADC->CR = (15 << 8);
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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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/* check if resolution is valid */
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if (res < 0xff) {
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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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/* set resolution */
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LPC_ADC->CR &= ~(0x7 << 17);
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LPC_ADC->CR |= res;
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/* Start a conversion */
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LPC_ADC->CR |= (1 << line) | (1 << 24);
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/* Wait for the end of the conversion */
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while (!(LPC_ADC->DR[line] & (1 << 31))) {}
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/* Read and return result */
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sample = (LPC_ADC->DR[line] >> 6);
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done();
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return sample;
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}
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