85 lines
2.6 KiB
C
85 lines
2.6 KiB
C
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/*
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Copyright 2016 Fred Sundvik <fsundvik@gmail.com>
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Jun Wako <wakojun@gmail.com>
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "lcd_backlight.h"
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#include "hal.h"
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#define RED_PIN 1
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#define GREEN_PIN 2
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#define BLUE_PIN 3
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#define CHANNEL_RED FTM0->CHANNEL[0]
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#define CHANNEL_GREEN FTM0->CHANNEL[1]
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#define CHANNEL_BLUE FTM0->CHANNEL[2]
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#define RGB_PORT PORTC
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#define RGB_PORT_GPIO GPIOC
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// Base FTM clock selection (72 MHz system clock)
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// @ 0xFFFF period, 72 MHz / (0xFFFF * 2) = Actual period
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// Higher pre-scalar will use the most power (also look the best)
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// Pre-scalar calculations
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// 0 - 72 MHz -> 549 Hz
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// 1 - 36 MHz -> 275 Hz
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// 2 - 18 MHz -> 137 Hz
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// 3 - 9 MHz -> 69 Hz (Slightly visible flicker)
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// 4 - 4 500 kHz -> 34 Hz (Visible flickering)
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// 5 - 2 250 kHz -> 17 Hz
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// 6 - 1 125 kHz -> 9 Hz
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// 7 - 562 500 Hz -> 4 Hz
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// Using a higher pre-scalar without flicker is possible but FTM0_MOD will need to be reduced
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// Which will reduce the brightness range
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#define PRESCALAR_DEFINE 0
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void lcd_backlight_hal_init(void) {
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// Setup Backlight
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SIM->SCGC6 |= SIM_SCGC6_FTM0;
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FTM0->CNT = 0; // Reset counter
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// PWM Period
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// 16-bit maximum
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FTM0->MOD = 0xFFFF;
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// Set FTM to PWM output - Edge Aligned, Low-true pulses
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#define CNSC_MODE FTM_SC_CPWMS | FTM_SC_PS(4) | FTM_SC_CLKS(0)
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CHANNEL_RED.CnSC = CNSC_MODE;
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CHANNEL_GREEN.CnSC = CNSC_MODE;
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CHANNEL_BLUE.CnSC = CNSC_MODE;
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// System clock, /w prescalar setting
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FTM0->SC = FTM_SC_CLKS(1) | FTM_SC_PS(PRESCALAR_DEFINE);
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CHANNEL_RED.CnV = 0;
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CHANNEL_GREEN.CnV = 0;
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CHANNEL_BLUE.CnV = 0;
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RGB_PORT_GPIO->PDDR |= (1 << RED_PIN);
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RGB_PORT_GPIO->PDDR |= (1 << GREEN_PIN);
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RGB_PORT_GPIO->PDDR |= (1 << BLUE_PIN);
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#define RGB_MODE PORTx_PCRn_SRE | PORTx_PCRn_DSE | PORTx_PCRn_MUX(4)
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RGB_PORT->PCR[RED_PIN] = RGB_MODE;
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RGB_PORT->PCR[GREEN_PIN] = RGB_MODE;
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RGB_PORT->PCR[BLUE_PIN] = RGB_MODE;
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}
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void lcd_backlight_hal_color(uint16_t r, uint16_t g, uint16_t b) {
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CHANNEL_RED.CnV = r;
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CHANNEL_GREEN.CnV = g;
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CHANNEL_BLUE.CnV = b;
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}
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