| /*************************************************************************** |
| * __________ __ ___. |
| * Open \______ \ ____ ____ | | _\_ |__ _______ ___ |
| * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / |
| * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < |
| * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ |
| * \/ \/ \/ \/ \/ |
| * $Id$ |
| * |
| * Copyright (C) 2006 by Wade Brown |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version 2 |
| * of the License, or (at your option) any later version. |
| * |
| * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY |
| * KIND, either express or implied. |
| * |
| ****************************************************************************/ |
| #include "cpu.h" |
| #include "system.h" |
| #include "adc-target.h" |
| #include "kernel.h" |
| |
| static unsigned short adc_readings[NUM_ADC_CHANNELS]; |
| |
| /* prototypes */ |
| static unsigned short __adc_read(int channel); |
| static void adc_tick(void); |
| |
| void adc_init(void) |
| { |
| int i; |
| |
| /* Turn on the ADC PCLK */ |
| s3c_regset(&CLKCON, 1<<15); |
| |
| /* Set channel 0, normal mode, disable "start by read" */ |
| ADCCON &= ~(0x3F); |
| |
| /* No start delay. Use normal conversion mode. */ |
| ADCDLY = 0x1; |
| |
| /* Set and enable the prescaler */ |
| ADCCON = (ADCCON & ~(0xff<<6)) | (0x19<<6); |
| ADCCON |= (1<<14); |
| |
| /* prefill the adc channels */ |
| for (i = 0; i < NUM_ADC_CHANNELS; i++) |
| { |
| adc_readings[i] = __adc_read(i); |
| } |
| |
| /* start at zero so when the tick starts it is at zero */ |
| adc_readings[0] = __adc_read(0); |
| |
| /* attach the adc reading to the tick */ |
| tick_add_task(adc_tick); |
| } |
| |
| /* Called to get the recent ADC reading */ |
| inline unsigned short adc_read(int channel) |
| { |
| return adc_readings[channel]; |
| } |
| |
| /** |
| * Read the ADC by polling |
| * @param channel The ADC channel to read |
| * @return 10bit reading from ADC channel or ADC_READ_ERROR if timeout |
| */ |
| static unsigned short __adc_read(int channel) |
| { |
| int i; |
| |
| /* Set the channel */ |
| ADCCON = (ADCCON & ~(0x7<<3)) | (channel<<3); |
| |
| /* Start the conversion process */ |
| ADCCON |= 0x1; |
| |
| /* Wait for a low Enable_start */ |
| for (i = 20000;;) |
| { |
| if(0 == (ADCCON & 0x1)) |
| { |
| break; |
| } |
| else |
| { |
| i--; |
| if (0 == i) |
| { |
| /* Ran out of time */ |
| return ADC_READ_ERROR; |
| } |
| } |
| } |
| |
| /* Wait for high End_of_Conversion */ |
| for(i = 20000;;) |
| { |
| if(ADCCON & (1<<15)) |
| { |
| break; |
| } |
| else |
| { |
| i--; |
| if(0 == i) |
| { |
| /* Ran out of time */ |
| return ADC_READ_ERROR; |
| } |
| } |
| } |
| return (ADCDAT0 & 0x3ff); |
| } |
| |
| /* add this to the tick so that the ADC converts are done in the background */ |
| static void adc_tick(void) |
| { |
| static unsigned channel; |
| |
| /* Check if the End Of Conversion is set */ |
| if (ADCCON & (1<<15)) |
| { |
| adc_readings[channel] = (ADCDAT0 & 0x3FF); |
| if (++channel >= NUM_ADC_CHANNELS) |
| { |
| channel = 0; |
| } |
| |
| /* setup the next conversion and start it*/ |
| ADCCON = (ADCCON & ~(0x7<<3)) | (channel<<3) | 0x01; |
| } |
| } |
| |