This commit is contained in:
lampmerchant 2022-06-21 20:22:42 -06:00
parent c4f06e0ee2
commit 3af5df9274
1 changed files with 24 additions and 9 deletions

View File

@ -407,7 +407,7 @@ Init
movlw B'00000010' ;MISO=RC1, INT=RA5=!ENBL
movlw B'00000010' ;MISO=RC1, SCK=RC0, INT=RA5=!ENBL
movlw B'00000011'
@ -415,6 +415,8 @@ Init
movlw B'00010001'
movlw B'00010000'
movlw B'00000101'
movwf INTPPS
@ -1776,10 +1778,14 @@ MmcIncAddr
;Send the command contained in M_CMDN and M_ADR3-0 to MMC card. Sets M_FAIL on
; fail. Trashes X0 and X1.
; fail. Trashes X0.
bcf M_FLAGS,M_FAIL ;Assume no failure to start with
movlb 4 ;Switch to the bank with the SSP registers
movf M_CMDN,W ;If this is a CMD0, skip over the ready check
xorlw 0x40 ; as card is not in SPI mode and may not be
btfsc STATUS,Z ; driving the MISO pin
bra MmcCmd1 ; "
movlw 8 ;Make sure the MMC card is ready for a command
movwf X0 ; by clocking up to 8 bytes to get an 0xFF
MmcCmd0 movlw 0xFF ;Clock a byte out of the MMC card while keeping
@ -1840,17 +1846,26 @@ MmcCmd1 clrf X0 ;Start the CRC7 register out at 0
;TODO for CMD12, it is necessary to clock and throw away a stuff byte?
movlw 8 ;Try to get status as many as eight times
movwf X0 ; "
movf M_CMDN,W ;If this is a CMD0, the bus may not be driven
xorlw 0x40 ; until the first clock, so we may get an all-
btfsc STATUS,Z ; ones response where the MSB reads as 0; set a
bsf X0,7 ; flag so we can respond to that
MmcCmd2 movlw 0xFF ;Clock a byte out of the MMC card while keeping
movwf SSP1BUF ; MOSI high
btfss SSP1STAT,BF ; "
bra $-1 ; "
incf SSP1BUF,W ;Read the received byte; if it's anything but
btfss STATUS,Z ; 0xFF, that's a result so skip ahead
bra MmcCmd3 ; "
decfsz X0,F ;Decrement the attempt counter until we've
bra MmcCmd2 ; tried eight times; if card hasn't responded
bsf M_FLAGS,M_FAIL ; by the eighth attempt, signal failure
MmcCmd3 decf WREG,W ;Decrement W so it reflects the last byte read
xorwf SSP1BUF,W ;Set Z flag if the received byte is all ones
btfsc X0,7 ;If this is the first byte from a CMD0, ignore
andlw 0x7F ; the MSB when checking for all ones
btfss STATUS,Z ;If the byte read is not all ones, it's a
bra MmcCmd3 ; result, so skip ahead
bcf X0,7 ;Clear the special CMD0 flag if it was set
decfsz X0,F ;Decrement attempt counter; if card hasn't
bra MmcCmd2 ; responded by eighth attempt, signal failure
bsf M_FLAGS,M_FAIL ; "
MmcCmd3 xorlw 0xFF ;Complement W so it reflects the last byte read
btfsc X0,7 ;If we're returning the first byte from a CMD0,
andlw 0x7F ; we should assume that the first bit was a 0
movlb 0 ;Restore BSR to 0 and return
return ; "