AT80SND1C-ROTIL datasheet(117/210 Pages) ATMEL

117 / 210 page

117

AT8xC51SND1C

4109E–8051–06/03

User may abort command loading by setting and clearing the CTPTR bit in MMCON0

Figure 82. Command Transmission Flow

Command Receiver

The end of the response reception is signalled to you by the EORI flag in MMINT regis-

ter. This flag may generate an MMC interrupt request as detailed in Section "Interrupt",

page 124. When this flag is set, 2 other flags in MMSTA register: RESPFS and CRC7S

give a status on the response received. RESPFS indicates if the response format is cor-

rect or not: the size is the one expected (48 bits or 136 bits) and a valid End bit has been

received, and CRC7S indicates if the CRC7 computation is correct or not. These Flags

are cleared when a command is sent to the card and updated when the response has

been received.

User may abort response reading by setting and clearing the CRPTR bit in MMCON0

According to the MMC specification delay between a command and a response (for-

mally N

CR parameter) can not exceed 64 MMC clock periods. To avoid any locking of

the MMC controller when card does not send its response (e.g. physically removed from

the bus), user must launch a time-out period to exit from such situation. In case of time-

out user may reset the command controller and its internal state machine by setting and

clearing the CCR bit in MMCON2 register.

This time-out may be disarmed when receiving the response.

Command

Transmission

Load Command in

Buffer

MMCMD = index

MMCMD = argument

Configure Response

RESPEN = X

RFMT = X

CRCDIS = X

Transmit Command

CMDEN = 1

CMDEN = 0

AT80SND1C-ROTIL Datasheet(PDF) 117 Page - ATMEL Corporation