lcd_backlight.hpp

// Copyright 2020 Kenta IDA
// LICENSE: Boost Software License
/**
 * @file lcd_backlight.hpp
*/

#ifndef LCD_BACKLIGHT_HPP__
#define LCD_BACKLIGHT_HPP__

//#include <samd51p19a.h>
#include <cstdint>

/**
 * @brief Controls Wio Terminal LCD back light brightness
 */
class LCDBackLight
{
private:
    std::uint8_t currentBrightness = 100;
    std::uint8_t maxBrightness = 100;
public:
    /**
     * @brief Gets current brightness
     * @return current brightness.
     */
    std::uint8_t getBrightness() const { return this->currentBrightness; }
    /**
     * @brief Gets maximum brightness
     * @return maximum brightness.
     */
    std::uint8_t getMaxBrightness() const { return this->maxBrightness; }
    
    /**
     * @brief Sets brightness.
     * @param [in] brightness new value of brightness. If the brightness value exceeds maximum brightness, the value will be clipped.
     * 
     */
    void setBrightness(std::uint8_t brightness)
    {
        this->currentBrightness = brightness < this->maxBrightness ? brightness : this->maxBrightness;
        TC0->COUNT8.CC[0].reg = this->currentBrightness;
        while(TC0->COUNT8.SYNCBUSY.bit.CC0);
    }
    /**
     * @brief Sets maximum brightness.
     * @param [in] maxBrightness new value of maximum brightness. If the current brightness value exceeds maximum brightness, the current brightness will be clipped.
     * 
     */
    void setMaxBrightness(std::uint8_t maxBrightness)
    {
        this->maxBrightness = maxBrightness;
        if( this->currentBrightness > this->maxBrightness ) {
            this->currentBrightness = this->maxBrightness;
        }
        TC0->COUNT8.PER.reg = this->maxBrightness;
        while(TC0->COUNT8.SYNCBUSY.bit.PER);
        TC0->COUNT8.CC[0].reg = this->currentBrightness;
        while(TC0->COUNT8.SYNCBUSY.bit.CC0);
    }

    /**
     * @brief Initialize hardware/peripherals to control back light brightness.
     * @remark This function must be called before using other LCDBackLight class member functions.
     */
    void initialize()
    {
        /* Enable Peripheral Clocks */
        GCLK->PCHCTRL[9].reg = 0 | (1u<<6);         // TC0, TC1
        while(!GCLK->PCHCTRL[9].bit.CHEN);
        GCLK->PCHCTRL[11].reg = 0 | (1u<<6);    // EVSYS[0]
        while(!GCLK->PCHCTRL[11].bit.CHEN);
        GCLK->PCHCTRL[33].reg = 0 | (1u<<6);    // CCL
        while(!GCLK->PCHCTRL[33].bit.CHEN);
        /* Enable Peropheral APB Clocks */
        MCLK->APBAMASK.bit.TC0_ = 1;
        MCLK->APBBMASK.bit.EVSYS_ = 1;
        MCLK->APBCMASK.bit.CCL_ = 1;

        /* Configure PORT */
        PORT->Group[2].DIRSET.reg = (1<<5);
        PORT->Group[2].EVCTRL.reg = 0x85; // PC05, OUT
        /* Configure EVSYS */
        EVSYS->USER[1].reg = 0x01;  // Channel0 -> PORT_EV0
        EVSYS->Channel[0].CHANNEL.reg = 0x74 | (0x02<<8) | (0x00<<10);  // CCL_LUTOUT0, ASYNCHRONOUS, NO_EVT_OUTPUT
        /* Configure CCL */
        CCL->CTRL.reg = (1<<0); // SWRST
        CCL->SEQCTRL[0].reg = 0x0; // Disable SEQCTRL
        CCL->LUTCTRL[0].reg = (0xaau << 24) | (1u<<22) | (0x6<<8) | (1<<1); // TRUTH=0xaa, LUTEO, INSEL0=0x06(TC), ENABLE
        CCL->CTRL.reg = (1<<1); // ENABLE

        /* Configure TC0 */
        TC0->COUNT8.CTRLA.reg = (1u<<0);   // SWRST;
        while( TC0->COUNT8.SYNCBUSY.bit.SWRST );
        
        TC0->COUNT8.CTRLA.reg = (0x01 << 2) | (0x01 << 4) | (0x04 << 8);   // MODE=COUNT8, PRESCALER=DIV16, PRESCSYNC=PRESC
        TC0->COUNT8.WAVE.reg  = 0x02; // WAVEGEN=NPWM;
        TC0->COUNT8.CTRLBSET.reg = (1u<<1); // LUPD
        TC0->COUNT8.PER.reg = this->maxBrightness;
        TC0->COUNT8.CC[0].reg = this->currentBrightness;
        TC0->COUNT8.CC[1].reg = 0u;
        TC0->COUNT8.DBGCTRL.bit.DBGRUN = 1;
        TC0->COUNT8.INTFLAG.reg = 0x33;    // Clear all flags
        while( TC0->COUNT8.SYNCBUSY.reg );
        
        TC0->COUNT8.CTRLA.bit.ENABLE = 1;   // ENABLE
        while( TC0->COUNT8.SYNCBUSY.bit.ENABLE );
    }
};
#endif //LCD_BACKLIGHT_HPP__