HD64570 HITACHI [Hitachi Semiconductor], HD64570 Datasheet - Page 181

• Manufacturer Part Number: HD64570
• Description: Serial Communications Adaptor
• Manufacturer: HITACHI [Hitachi Semiconductor]

Table 5.8
Read Mode
Word read
Byte read
Notes: 1. Data byte count in the receive buffer is reflected by the CDE1 and CDE0 bits of current
TRB write operation: Data is written to the transmit buffer at TRB write in the procedure as
listed in table 5.9 to table 5.11.
2. TRBH and TRBL are simultaneously accessed in word read mode, and either TRBH or
3. Data 0 and 1 are arranged in the order shown in figures 5.8 (a) and (b). The serial unit
4. If undefined data is read, subsequent operation is not guaranteed. Undefined data is
status registers 1 and 0 (CTS1 and CTS0).
TRBL is accessed in byte read mode.
sends data 0 and data 1 to the receive buffer in that order.
not read in a built-in DMA transfer.
TRB Read Operation in CPU Modes 2, 3
Accessed Register*
TRBH
TRBL
TRBH
TRBL
(a) 2 Bytes of Data
Figure 5.8 Data Arrangement in Receive Buffer
in RX FIFO
Data 0
Data 1
2
2 or More Bytes
Data 0*
Data 1*
Data 0*
Data 0*
3
3
3
3
Data Byte Count in Receive Buffer*
(b) 1 Byte of Data
in RX FIFO
Data 0
Rev. 0, 07/98, page 165 of 453
1 Byte
Data 0*
Undefined*
Data 0*
Data 0*
3
3
3
4
None
Undefined*
Undefined*
Undefined*
Undefined*
1
4
4
4
4