LIST P=16F687, R=DEC, ST=OFF, MM=OFF INCLUDE "p16F687.inc" __CONFIG _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _CP_OFF & _CPD_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _HS_OSC #define BAUD 2400 ; baud rate #define XTAL 20 ; crystal freq in MHz #define X ((XTAL*1000000)/(BAUD*64))-1 #define CS PORTC,6 ; Data segment CBLOCK 0x20 ind, msgNo, temp, cnt ; local variables cmd, crc ; MMC command and CRC7 check arg:4 ; MMC command argument resp ; MMC response ENDC ; Code segment ORG 0 goto main ORG 4 retfie msg1 movf ind, w addwf PCL, f dt 13, 10, 13, 10, "UART module is running", 13, 10, 0 msg2 movf ind, w addwf PCL, f dt "MMC module is active", 13, 10, 0 msg3 movf ind, w addwf PCL, f dt " CMD0 is through", 13, 10, 0 msg4 movf ind, w addwf PCL, f dt " CMD1 is through", 13, 10, 0 msg5 movf ind, w addwf PCL, f dt " MMC error", 13, 10, 0 msg6 movf ind, w addwf PCL, f dt " reading block: ", 13, 10, 0 msg7 movf ind, w addwf PCL, f dt 13, 10, "end of code", 13, 10, 0 msg8 movf ind, w addwf PCL, f dt " writing block...", 13, 10, 0 msg9 movf ind, w addwf PCL, f dt " block size is set", 13, 10, 0 getNextChar movf msgNo, w addwf PCL, f return goto msg1 goto msg2 goto msg3 goto msg4 goto msg5 goto msg6 goto msg7 goto msg8 goto msg9 sendChar btfss PIR1, TXIF ; TX buffer is full? goto $-1 ; YES - wait movwf TXREG ; send out byte return sendString ; outputs string with number in WREG movwf msgNo ; set message number clrf ind ; start the message movf ind, w ; next char index call getNextChar ; get next char addlw 0 ; set bit Z in STATUS btfsc STATUS, Z ; end of string? return ; YES - return btfss PIR1, TXIF ; TX buffer is full? goto $-1 ; YES - wait movwf TXREG ; send out byte incf ind, f ; get to the next char goto sendString+2 return spi_io ; send/receive byte via SPI movwf SSPBUF ; put data to send in WREG into SSPBUF btfss SSPCON, WCOL ; data sent? goto $+3 ; YES - proceed bcf SSPCON, WCOL ; NO - reset WCOL and try again goto $-4 bsf STATUS, RP0 ; switch to BANK 1 btfss SSPSTAT ^ 0x80, BF ; buffer full? goto $-1 ; NO - wait bcf STATUS, RP0 ; back to BANK 0 movf SSPBUF, w ; return the received data in WREG return sendMMC ; send command to MMC movlw 0xFF call spi_io movf cmd, w ; send the command byte call spi_io movf arg+3, w ; send 4 argument bytes starting with call spi_io movf arg+2, w call spi_io movf arg+1, w call spi_io movf arg, w call spi_io movf crc, w ; send the CRC7 byte call spi_io wait_resp ; wait a response for at most 8 cycles movlw 0xFF ; waiting for MMC responce call spi_io movwf temp ; save response addlw 48 ; ASCII conversion call sendChar ; print response movf temp, w ; restore response subwf resp, w ; expected responce? btfsc STATUS, Z retlw 0 ; YES - return decfsz cnt, f ; waiting period is over? goto wait_resp ; NO - keep waiting retlw 1 initMMC bsf CS ; disable MMC movlw 10 movwf ind ; send 80 dummy clocks movlw 0xFF call spi_io decfsz ind, f goto $-3 bcf CS ; enable MMC movlw 0x40 ; ************** send CMD0 movwf cmd clrf arg clrf arg+1 clrf arg+2 clrf arg+3 movlw 0x95 movwf crc movlw 1 ; expected response movwf resp movlw 8 ; maximum number of cycles movwf cnt ; to wait for expected response call sendMMC addlw 0 ; set Z flag movlw 3 ; message of success btfss STATUS, Z movlw 5 ; report an error call sendString movlw 0x41 ; **************** send CMD1 movwf cmd clrf arg clrf arg+1 clrf arg+2 clrf arg+3 movlw 0xFF movwf crc clrf resp ; expected response movlw 2 movwf cnt call sendMMC addlw 0 btfss STATUS, Z goto $-14 movlw 4 ; message of success btfss STATUS, Z movlw 5 call sendString return main bsf CS ; disable MMC bsf STATUS, RP1 ; switch to BANK 2 clrf ANSEL ^ 0x100 ; set all pins digital clrf ANSELH ^ 0x100 bcf STATUS, RP1 bsf STATUS, RP0 ; switch to BANK 1 movlw b'111000' ; setup I/O ports movwf TRISA ^ 0x80 movlw b'10110000' movwf TRISB ^ 0x80 clrf TRISC ^ 0x80 movlw X ; load the baud rate generator movwf SPBRG ^ 0x80 movlw b'00100000' ; enable TX for 8 data bits movwf TXSTA ^ 0x80 bcf SSPSTAT ^ 0x80, SMP ; input is ready at the middle of clock bcf SSPSTAT ^ 0x80, CKE ; bcf STATUS, RP0 ; switch to BANK 0 movlw b'10010000' ; enable USART for 8 data bits movwf RCSTA ; this automatically configures TX and RX pins movlw 1 ; display message1 call sendString ; if UART is working bsf SSPCON, CKP ; idle state for clock is high bsf SSPCON, SSPM1 ; FOSC/64 speed bsf SSPCON, SSPEN ; enable SPI master call initMMC ;*******SET BLOCK SIZE 512 Bytes movlw 0x50 ; ************** send CMD movwf cmd clrf arg ; arg = 512 movlw 2 movwf arg+1 clrf arg+2 clrf arg+3 movlw 0xFF movwf crc clrf resp movlw 8 movwf cnt call sendMMC addlw 0 movlw 9 ; message of success btfss STATUS, Z movlw 5 ; error message call sendString ;*******WRITING IN 512-BYTE MODE movlw 0x58 ; ************** send CMD movwf cmd clrf arg ; arg = 512 movlw 2 movwf arg+1 clrf arg+2 clrf arg+3 movlw 0xFF movwf crc clrf resp movlw 8 movwf cnt call sendMMC addlw 0 movlw 8 ; message of success btfss STATUS, Z movlw 5 ; error message call sendString movlw 0xFF ; write prefix call spi_io movlw 0xFF call spi_io movlw 0xFE call spi_io movlw 255 ; output first 255 chars movwf cnt movlw 65 call spi_io ; get data byte decfsz cnt, f goto $-3 movlw 255 ; output next 255 chars movwf cnt movlw 66 call spi_io ; get data byte decfsz cnt, f goto $-3 movlw 67 call spi_io ; get data byte movlw 68 call spi_io ; get data byte movlw 0xFF ; write 2 bytes CRC call spi_io movlw 0xFF call spi_io movlw 0xFF ; wait for 0xFF call spi_io sublw 0xFF btfss STATUS, Z goto $-4 ;*****READING in 512-BYTE MODE movlw 0x51 ; ************** send CMD movwf cmd clrf arg ; arg = 512 movlw 2 movwf arg+1 clrf arg+2 clrf arg+3 movlw 0xFF movwf crc clrf resp movlw 8 movwf cnt call sendMMC addlw 0 movlw 6 ; message of success btfss STATUS, Z movlw 5 ; error message call sendString movlw 0xFF ; wait for 0xFE call spi_io sublw 0xFE btfss STATUS, Z goto $-4 movlw 255 ; output first 255 chars movwf cnt movlw 0xFF call spi_io ; get data byte call sendChar ; send it to PC decfsz cnt, f goto $-4 movlw 255 ; output next 255 chars movwf cnt movlw 0xFF call spi_io ; get data byte call sendChar ; send it to PC decfsz cnt, f goto $-4 movlw 0xFF call spi_io ; get data byte call sendChar ; send it to PC movlw 0xFF call spi_io ; get data byte call sendChar ; send it to PC movlw 0xFF ; read 2 bytes CRC call spi_io movlw 0xFF call spi_io L10 bsf CS movlw 7 call sendString goto $ END