e454d88b88
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22103 a1c6a512-1295-4272-9138-f99709370657
99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2009 by Bertrik Sikken
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include <stdbool.h>
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#include "config.h"
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#include "backlight.h"
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#include "backlight-target.h"
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#include "system.h"
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/*
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Backlight driver using the PWM mode of a hardware timer.
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The PWM duty cycle depends exponentially on the configured brightness
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level. This makes the brightness curve more linear to the human eye.
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The button LEDs are all activated at the same time (even though there
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are three individually controllable groups: menu/back, cursor, middle).
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*/
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void _backlight_set_brightness(int brightness)
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{
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/* pwm = round(sqrt(2)**x), where brightness level x = 1..16 */
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static const unsigned int logtable[] =
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{1, 2, 3, 4, 6, 8, 11, 16, 23, 32, 45, 64, 91, 128, 181, 256};
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/* set PWM width */
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TADATA0 = logtable[brightness];
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}
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void _backlight_on(void)
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{
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/* configure backlight pin P0.0 as timer PWM output */
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PCON0 = ((PCON0 & ~(3 << 0)) | (2 << 0));
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_backlight_set_brightness(backlight_brightness);
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}
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void _backlight_off(void)
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{
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/* configure backlight pin P0.0 as GPIO and switch off */
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PCON0 = ((PCON0 & ~(3 << 0)) | (1 << 0));
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PDAT0 &= ~(1 << 0);
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}
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void _buttonlight_on(void)
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{
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PDAT3 |= (3 << 2);
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PDAT4 |= (1 << 2);
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}
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void _buttonlight_off(void)
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{
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PDAT3 &= ~(3 << 2);
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PDAT4 &= ~(1 << 2);
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}
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bool _backlight_init(void)
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{
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/* Enable button LEDs: P3.2 (menu/back), P3.3 (cursor), P4.2 (middle) */
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PCON3 = (PCON3 & ~0x0000FF00) | 0x00001100;
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PCON4 = (PCON4 & ~0x00000F00) | 0x00000100;
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/* enable timer clock */
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PWRCON &= ~(1 << 4);
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/* configure timer */
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TACMD = (1 << 1); /* TA_CLR */
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TACON = (0 << 13) | /* TA_INT1_EN */
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(0 << 12) | /* TA_INT0_EN */
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(1 << 11) | /* TA_START */
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(3 << 8) | /* TA_CS = PCLK / 64 */
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(1 << 4); /* TA_MODE_SEL = PWM mode */
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TADATA1 = 256; /* set PWM period */
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TAPRE = 20; /* prescaler */
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TACMD = (1 << 0); /* TA_EN */
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_backlight_on();
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return true;
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}
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