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80 lines
2.4 KiB
80 lines
2.4 KiB
6 years ago
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#include "u8x8_avr.h"
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#include <util/delay.h>
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#define P_CPU_NS (1000000000UL / F_CPU)
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uint8_t u8x8_byte_avr_hw_spi(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr) {
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uint8_t *data;
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switch(msg) {
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case U8X8_MSG_BYTE_INIT:
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DDRB |= (1 << 1); // CLOCK (SCLK)
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DDRB |= (1 << 2); // DATA (MOSI)
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SPSR |= (1 << SPI2X); // SPI2X: Double SPI Speed bit
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SPCR = ((1 << SPE) | (1 << MSTR)); // Enable / Master
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u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
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break;
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case U8X8_MSG_BYTE_SET_DC:
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u8x8_gpio_SetDC(u8x8, arg_int);
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break;
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case U8X8_MSG_BYTE_START_TRANSFER:
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u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_enable_level);
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u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->post_chip_enable_wait_ns, NULL);
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break;
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case U8X8_MSG_BYTE_SEND:
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data = (uint8_t *)arg_ptr;
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while( arg_int > 0 ) {
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SPDR = (uint8_t)*data;
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while (!(SPSR & _BV(SPIF)));
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data++;
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arg_int--;
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}
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break;
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case U8X8_MSG_BYTE_END_TRANSFER:
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u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->pre_chip_disable_wait_ns, NULL);
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u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
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break;
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default:
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return 0;
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}
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return 1;
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}
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uint8_t u8x8_avr_delay(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
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{
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uint8_t cycles;
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switch(msg){
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case U8X8_MSG_DELAY_NANO: // delay arg_int * 1 nano second
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// At 20Mhz, each cycle is 50ns, the call itself is slower.
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break;
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case U8X8_MSG_DELAY_100NANO: // delay arg_int * 100 nano seconds
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// Approximate best case values...
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#define CALL_CYCLES 26UL
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#define CALC_CYCLES 4UL
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#define RETURN_CYCLES 4UL
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#define CYCLES_PER_LOOP 4UL
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cycles = (100UL * arg_int) / (P_CPU_NS * CYCLES_PER_LOOP);
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if(cycles > CALL_CYCLES + RETURN_CYCLES + CALC_CYCLES) break;
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__asm__ __volatile__ (
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"1: sbiw %0,1" "\n\t" // 2 cycles
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"brne 1b" : "=w" (cycles) : "0" (cycles) // 2 cycles
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);
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break;
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case U8X8_MSG_DELAY_10MICRO: // delay arg_int * 10 micro seconds
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for(int i=0 ; i < arg_int ; i++)
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_delay_us(10);
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break;
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case U8X8_MSG_DELAY_MILLI: // delay arg_int * 1 milli second
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for(int i=0 ; i < arg_int ; i++)
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_delay_ms(1);
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break;
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default:
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return 0;
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}
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return 1;
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}
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