Rainbow Electronics AT89C5132 - Manual (Page 91)

91
AT8xC5132
4173A–8051–08/02
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 65. Data Line Controller Block Diagram
FIFO Implementation The 16-byte FIFO is based on a dual 8-byte FIFO managed using two 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 93. Figure 66 summarizes the data modes configuration flows.
Table 93. Block Length Programming
MCBI
MMINT.1
DATFS
MMSTA.3
CRC16S
MMSTA.4
F2FI
MMINT.3
F2EI
MMINT.1
DFMT
MMCON0.2
MBLOCK
MMCON0.3
DATDIR
MMCON1.3
Data Converter
// -> Serial
BLEN3:0
MMCON1.7:4
DATEN
MMCON1.2
DATA Line
Finished State Machine
Data Converter
Serial -> //
DTPTR
MMCON0.6
DRPTR
MMCON0.7
TX Pointer
RX Pointer
8-byte
FIFO 1
8-byte
FIFO 2
16-byte FIFO
MMDAT
F1EI
MMINT.0
CRC16 and Format
Checker
F1FI
MMINT.2
EOFI
MMINT.4
CBUSY
MMSTA.5
CRC16
Generator
MDAT
BLEN3:0 Block Length (Byte)
BLEN = 0000 to 1011 Length = 2 BLEN : 1 to 2048
> 1011 Reserved: do not program BLEN3:0 > 1011