st9720 LCD SPI 与 ATmega328P 通信

Question

我目前正在尝试向使用 ST9720 的 LCD 写入一个简单的字符串，当我运行我提供的用于打印简单字符串的代码时，LCD 上出现了相当多的噪音。我不知道为什么，我想也许是时钟值，但我很不确定应该设置什么，以消除 LCD 上的噪音。 LCD接一个atmega328P芯片，该芯片接一个通过spi通讯的avr编程器。这也使用 atmel，我从 https://github.com/olikraus/u8g2/wiki/u8g2as7 获取代码 它使用 u8g2 库。任何帮助表示赞赏。

#include <avr/io.h>
#include <u8g2.h>
#include <util/delay.h>

#define DISPLAY_CLK_DIR DDRB
#define DISPLAY_CLK_PORT PORTB
#define DISPLAY_CLK_PIN 5

#define DISPLAY_DATA_DIR DDRB
#define DISPLAY_DATA_PORT PORTB
#define DISPLAY_DATA_PIN 3

#define DISPLAY_CS_DIR DDRB
#define DISPLAY_CS_PORT PORTB
#define DISPLAY_CS_PIN 2

//#define DISPLAY_DC_DIR DDRB
//#define DISPLAY_DC_PORT PORTB
//#define DISPLAY_DC_PIN 1

#define DISPLAY_RESET_DIR DDRB
#define DISPLAY_RESET_PORT PORTB
#define DISPLAY_RESET_PIN 0


#define P_CPU_NS (1000000000UL / F_CPU)

u8g2_t u8g2;

uint8_t u8x8_avr_delay(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
{
    uint8_t cycles;

    switch(msg)
    {
        case U8X8_MSG_DELAY_NANO:     // delay arg_int * 1 nano second
            // At 20Mhz, each cycle is 50ns, the call itself is slower.
            break;
        case U8X8_MSG_DELAY_100NANO:    // delay arg_int * 100 nano seconds
            // Approximate best case values...
#define CALL_CYCLES 26UL
#define CALC_CYCLES 4UL
#define RETURN_CYCLES 4UL
#define CYCLES_PER_LOOP 4UL

            cycles = (100UL * arg_int) / (P_CPU_NS * CYCLES_PER_LOOP);

            if(cycles > CALL_CYCLES + RETURN_CYCLES + CALC_CYCLES) 
                break;

            __asm__ __volatile__ (
            "1: sbiw %0,1" "\n\t" // 2 cycles
            "brne 1b" : "=w" (cycles) : "0" (cycles) // 2 cycles
            );
            break;
        case U8X8_MSG_DELAY_10MICRO:    // delay arg_int * 10 micro seconds
            for(int i=0 ; i < arg_int ; i++)
                _delay_us(10);
            break;
        case U8X8_MSG_DELAY_MILLI:      // delay arg_int * 1 milli second
            for(int i=0 ; i < arg_int ; i++)
                _delay_ms(1);
            break;
        default:
            return 0;
    }
    return 1;
}


uint8_t u8x8_avr_gpio_and_delay(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
{
    // Re-use library for delays

    switch(msg)
    {
        case U8X8_MSG_GPIO_AND_DELAY_INIT:  // called once during init phase of u8g2/u8x8
            DISPLAY_CLK_DIR |= 1<<DISPLAY_CLK_PIN;
            DISPLAY_DATA_DIR |= 1<<DISPLAY_DATA_PIN;
            DISPLAY_CS_DIR |= 1<<DISPLAY_CS_PIN;
            //DISPLAY_DC_DIR |= 1<<DISPLAY_DC_PIN;
            DISPLAY_RESET_DIR |= 1<<DISPLAY_RESET_PIN;
            break;              // can be used to setup pins
        case U8X8_MSG_GPIO_SPI_CLOCK:        // Clock pin: Output level in arg_int
            if(arg_int)
                DISPLAY_CLK_PORT |= (1<<DISPLAY_CLK_PIN);
            else
                DISPLAY_CLK_PORT &= ~(1<<DISPLAY_CLK_PIN);
            break;
        case U8X8_MSG_GPIO_SPI_DATA:        // MOSI pin: Output level in arg_int
            if(arg_int)
                DISPLAY_DATA_PORT |= (1<<DISPLAY_DATA_PIN);
            else
                DISPLAY_DATA_PORT &= ~(1<<DISPLAY_DATA_PIN);
            break;
        case U8X8_MSG_GPIO_CS:        // CS (chip select) pin: Output level in arg_int
            if(arg_int)
                DISPLAY_CS_PORT |= (1<<DISPLAY_CS_PIN);
            else
                DISPLAY_CS_PORT &= ~(1<<DISPLAY_CS_PIN);
            break;
        //case U8X8_MSG_GPIO_DC:        // DC (data/cmd, A0, register select) pin: Output level in arg_int
        //  if(arg_int)
        //      DISPLAY_DC_PORT |= (1<<DISPLAY_DC_PIN);
        //  else
        //      DISPLAY_DC_PORT &= ~(1<<DISPLAY_DC_PIN);
        //  break;
        
        case U8X8_MSG_GPIO_RESET:     // Reset pin: Output level in arg_int
            if(arg_int)
                DISPLAY_RESET_PORT |= (1<<DISPLAY_RESET_PIN);
            else
                DISPLAY_RESET_PORT &= ~(1<<DISPLAY_RESET_PIN);
            break;
        default:
            if (u8x8_avr_delay(u8x8, msg, arg_int, arg_ptr))    // check for any delay msgs
                return 1;
            u8x8_SetGPIOResult(u8x8, 1);      // default return value
            break;
    }
    return 1;
}

int main(void)
{
    /*
        Select a setup procedure for your display from here: https://github.com/olikraus/u8g2/wiki/u8g2setupc
        1. Arg: Address of an empty u8g2 structure
        2. Arg: Usually U8G2_R0, others are listed here: https://github.com/olikraus/u8g2/wiki/u8g2reference#carduino-example
        3. Arg: Protocol procedure (u8g2-byte), list is here: https://github.com/olikraus/u8g2/wiki/Porting-to-new-MCU-platform#communication-callback-eg-u8x8_byte_hw_i2c
        4. Arg: Defined in this code itself (see above)
    */
    u8g2_Setup_st7920_s_128x64_1(&u8g2, U8G2_R0, u8x8_byte_4wire_sw_spi, u8x8_avr_gpio_and_delay);
    u8g2_InitDisplay(&u8g2);
    u8g2_SetPowerSave(&u8g2, 0);
    
    /* full buffer example, setup procedure ends in _f */
    u8g2_ClearBuffer(&u8g2);
    u8g2_SetFont(&u8g2, u8g2_font_ncenB14_tr);
    u8g2_DrawStr(&u8g2, 1, 18, "U8g2 on AVR");
    u8g2_SendBuffer(&u8g2);
        
    while(1){
    }
}

Answer 1

使用u8g2_Setup_st7920_s_128x64_f() 而不是u8g2_Setup_st7920_s_128x64_1()。