Data Line Controller
The data line controller is based on a 16-Byte FIFO used both by the data transmitter
channel and by the data receiver channel.
Figure 95. Data Line Controller Block Diagram
MMINT.0
MMINT.2
MMSTA.3
MMSTA.4
F1EI
F1FI
DATFS CRC16S
CRC16 and Format
Checker
Data Converter
Serial -> //
8-Byte
TX Pointer
FIFO 1
MCBI
MMINT.1
CBUSY
MMSTA.5
MDAT
DTPTR
MMCON0.6
16-Byte FIFO
MMDAT
Data Converter
// -> Serial
CRC16
Generator
RX Pointer
DRPTR
MMCON0.7
8-Byte
FIFO 2
MMINT.4
DATA Line
Finished State Machine
EOFI
DFMT
MBLOCK DATEN DATDIR BLEN3:0
MMCON0.2 MMCON0.3 MMCON1.2 MMCON1.3 MMCON1.7:4
F2EI
MMINT.1
F2FI
MMINT.3
FIFO Implementation
The 16-Byte FIFO is based on a dual 8-Byte FIFOs managed using 2 pointers and four
flags indicating the status full and empty of each FIFO.
Pointers are not accessible to user but can be reset at any time by setting and clearing
DRPTR and DTPTR bits in MMCON0 register. Resetting the pointers is equivalent to
abort the writing or reading of data.
F1EI and F2EI flags in MMINT register signal when set that respectively FIFO1 and
FIFO2 are empty. F1FI and F2FI flags in MMINT register signal when set that respec-
tively FIFO1 and FIFO2 are full. These flags may generate an MMC interrupt request as
detailed in Section “Interrupt”.
Data Configuration
Before sending or receiving any data, the data line controller must be configured accord-
ing to the type of the data transfer considered. This is achieved using the Data Format
bit: DFMT in MMCON0 register. Clearing DFMT bit enables the data stream format
while setting DFMT bit enables the data block format. In data block format, user must
also configure the single or multi-block mode by clearing or setting the MBLOCK bit in
MMCON0 register and the block length using BLEN3:0 bits in MMCON1 according to
Table 144. Figure 96 summarizes the data modes configuration flows.
Table 144. Block Length Programming
BLEN3:0
BLEN = 0000 to 1011
> 1011
Block Length (Byte)
Length = 2BLEN: 1 to 2048
Reserved: do not program BLEN3:0 > 1011
144
AT8xC51SND2C
4341D–MP3–04/05
ATMEL [ ATMEL ]
