ssd1306_spi_avr.c

/*
    MIT License

    Copyright (c) 2018-2019, Alexey Dynda

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    SOFTWARE.
*/

#include "ssd1306_spi_avr.h"
#include "ssd1306_spi.h"

#include "intf/ssd1306_interface.h"
#include "lcd/lcd_common.h"
#include "ssd1306_hal/io.h"

#if defined(CONFIG_AVR_SPI_AVAILABLE) && defined(CONFIG_AVR_SPI_ENABLE)

#include <stdlib.h>

#define PORT_SPI    PORTB
#define DDR_SPI     DDRB

#if defined(__AVR_ATmega2560__) || defined(__AVR_ATmega1280__)
    #define DD_MISO     DDB3
    #define DD_MOSI     DDB2
    #define DD_SCK      DDB1
    #define DD_SS       DDB0
#else
    #define DD_MISO     DDB4
    #define DD_MOSI     DDB3
    #define DD_SCK      DDB5
    #define DD_SS       DDB2
#endif

#define SPI_CLOCK_MASK   0x03
#define SPI_2XCLOCK_MASK 0x01

extern uint32_t s_ssd1306_spi_clock;

static void ssd1306_spiConfigure_avr()
{
    uint8_t clockDiv;
    uint32_t clockSetting = F_CPU / 2;
    clockDiv = 0;
    while ((clockDiv < 6) && (s_ssd1306_spi_clock < clockSetting))
    {
        clockSetting /= 2;
        clockDiv++;
    }
    if (clockDiv == 6)
    {
        clockDiv = 7;
    }
    // Invert the SPI2X bit
    clockDiv ^= 0x1;

    // SS pin must be HIGH, when enabling MASTER SPI mode
    // Otherwise, SPI will drop automatically to SLAVE mode
    DDR_SPI &= ~((1<<DD_SCK)|(1<<DD_SS)|(1<<DD_MOSI));
    PORT_SPI |= (1<<DD_SS);
    /* Define the following pins as output */
    DDR_SPI |= ((1<<DD_MOSI)|(1<<DD_SCK)|(1<<DD_SS));
    PORT_SPI |= (1<<DD_SS);

    SPCR =  (1<<SPE)|(1<<MSTR)|(0<<CPOL)|(0<<CPHA)|
            ((clockDiv >> 1) & SPI_CLOCK_MASK);
    SPSR = clockDiv & SPI_2XCLOCK_MASK; // Double Clock Rate
    // Wait for some time to give SPI HW module to initialize
    delay(10);
}

static void ssd1306_spiClose_avr()
{
}

static void ssd1306_spiStart_avr()
{
    if (s_ssd1306_cs >= 0)
    {
        digitalWrite(s_ssd1306_cs,LOW);
    }
}

static void ssd1306_spiSendByte_avr(uint8_t data)
{
    SPDR = data;
    asm volatile("nop");
    while((SPSR & (1<<SPIF))==0);
}

static void ssd1306_spiSendBytes_avr(const uint8_t * buffer, uint16_t size)
{
    while (size--)
    {
        SPDR = *buffer;
        asm volatile("nop"); // to improve speed
        while((SPSR & (1<<SPIF))==0);
        SPDR; // read SPI input
        buffer++;
    }
}

static void ssd1306_spiStop_avr()
{
    if (ssd1306_lcd.type == LCD_TYPE_PCD8544)
    {
        digitalWrite(s_ssd1306_dc, LOW);
        ssd1306_spiSendByte_avr( 0x00 ); // Send NOP command to allow last data byte to pass (bug in PCD8544?)
                                         // ssd1306 E3h is NOP command
    }
    if (s_ssd1306_cs >= 0)
    {
        digitalWrite(s_ssd1306_cs, HIGH);
    }
}

void ssd1306_spiInit_avr(int8_t cesPin, int8_t dcPin)
{
    if (cesPin >=0) pinMode(cesPin, OUTPUT);
    if (dcPin >= 0) pinMode(dcPin, OUTPUT);
    if (cesPin) s_ssd1306_cs = cesPin;
    if (dcPin) s_ssd1306_dc = dcPin;
    ssd1306_intf.spi = 1;
    ssd1306_spiConfigure_avr();
    ssd1306_intf.start = ssd1306_spiStart_avr;
    ssd1306_intf.stop = ssd1306_spiStop_avr;
    ssd1306_intf.send = ssd1306_spiSendByte_avr;
    ssd1306_intf.send_buffer = ssd1306_spiSendBytes_avr;
    ssd1306_intf.close = ssd1306_spiClose_avr;
}

#endif