实现AVR ATmega48与ATmega168单片机SPI互连通信，采用主从切换方式。-Achieve AVR ATmega48 and the ATmega168 MCU SPI interconnect communications, use of master-slave switch method.

SPI lib for atmega168. DON USE Wrk? UNOS void spi_init(void) { /* Set MOSI and SCK output */ DDR_SPI |= _BV(DD_MOSI) | _BV(DD_SCK) DDR_SPI &= ~_BV(DD_MISO) /* Enable SPI, Master, set clock rate fck/128 */ SPCR = _BV(SPE) | _B

Reading an SD card with an ATMEGA168