AT89C5132-ROTIL datasheet(94/182 Pages) ATMEL

94 / 182 page

4173E–USB–09/07

AT89C5132

Figure 16-17. Data Block Transmission Flows

16.6.4

Data Receiver

16.6.4.1

Configuration

To receive data from the card, the user must first configure the data controller in reception mode

by clearing the DATDIR bit in MMCON1 register.

Figure 16-18 summarizes the data stream reception flows in both polling and interrupt modes

while Figure 16-19 summarizes the data block reception flows in both polling and interrupt

modes, these flows assume that block length is greater than 16 Bytes.

16.6.4.2

Data Reception

The end of data frame (block or stream) reception is signalled by the EOFI flag in MMINT regis-

ter. This flag may generate an MMC interrupt request as detailed in Section "Interrupt", page 96.

When this flag is set, two other flags in MMSTA register: DATFS and CRC16S give a status on

the frame received. DATFS indicates if the frame format is correct or not: a valid End bit has

been received, and CRC16S indicates if the CRC16 computation is correct or not. In case of

data stream CRC16S has no meaning and stays cleared.

According to the MMC specification data transmission, the card starts after the access time

delay (formally NAC parameter) beginning from the End bit of the read command. To avoid any

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

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

Data Block

Transmission

Start Transmission

DATEN = 1

DATEN = 0

FIFO Empty?

F1EI or F2EI = 1?

FIFO Filling

Write 8 Data to MMDAT

No More Data

To Send?

FIFOs Filling

Write 16 Data to MMDAT

a. Polling Mode

Data Block

Initialization

Start Transmission

DATEN = 1

DATEN = 0

FIFOs Filling

Write 16 Data to MMDAT

Data Block

Transmission ISR

FIFO Filling

Write 8 Data to MMDAT

No More Data

to Send?

b. Interrupt Mode

FIFO Empty?

F1EI or F2EI = 1?

Mask FIFOs Empty

F1EM = 1

F2EM = 1

Unmask FIFOs Empty

F1EM = 0

F2EM = 0

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