firmware/target/coldfire/mpio/adc-mpio.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2010 Marcin Bukat
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21
  22 #include "config.h"
  23 #include "cpu.h"
  24 #include "system.h"
  25 #include "kernel.h"
  26 #include "thread.h"
  27 #include "adc.h"
  28
  29 volatile unsigned short adc_data[NUM_ADC_CHANNELS] IBSS_ATTR;
  30
  31 /* Reading takes 4096 adclk ticks
  32  * 1) tick task is created that enables ADC interrupt
  33  * 2) On interrupt single channel is readed and
  34  *    ADC is prepared for next channel
  35  * 3) When all 4 channels are scanned ADC interrupt is disabled
  36  */
  37
  38 void ADC(void) __attribute__ ((interrupt_handler,section(".icode")));
  39 void ADC(void)
  40 {
  41     static unsigned char channel IBSS_ATTR;
  42     /* read current value */
  43     adc_data[(channel&0x03)] = ADVALUE;
  44
  45     /* switch channel
  46      *
  47      * set source remark
  48      * ADCONFIG is 16bit wide so we have to shift data by 16bits left
  49      * thats why we shift <<24 instead of <<8
  50      */
  51
  52     channel++;
  53
  54     and_l(~(0x03<<24),&ADCONFIG);
  55     or_l( (((channel&0x03) << 8 )|(1<<7))<<16, &ADCONFIG);
  56
  57     if ( (channel & 0x03) == 0 )
  58         /* disable ADC interrupt */
  59         and_l((~(1<<6))<<16,&ADCONFIG);
  60 }
  61
  62 unsigned short adc_scan(int channel)
  63 {
  64     /* maybe we can drop &0x03 part */
  65     return adc_data[(channel&0x03)];
  66 }
  67
  68 void adc_tick(void)
  69 {
  70     /* enable ADC interrupt */
  71     or_l( ((1<<6))<<16, &ADCONFIG);
  72 }
  73
  74 void adc_init(void)
  75 {
  76     /* GPIO38 GPIO39 */
  77     and_l(~((1<<6)|(1<<7)), &GPIO1_FUNCTION);
  78
  79     /* ADOUT_SEL = 01
  80      * SOURCE SELECT = 000
  81      * CLEAR INTERRUPT FLAG
  82      * ENABLE INTERRUPT = 0
  83      * ADOUT_DRIVE = 00
  84      * ADCLK_SEL = 011 (busclk/8)
  85      */
  86
  87     ADCONFIG = (1<<10)|(1<<8)|(1<<7)|0x03;
  88
  89     /* ADC interrupt level 4.0 */
  90     or_l((4<<28), &INTPRI8);
  91
  92     /* create tick task which enables ADC interrupt */
  93     tick_add_task(adc_tick);
  94
  95     /* let the interrupt handler fill readout array */
  96     sleep(2);
  97 }