38K2 Datasheet, PDF (79/151 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

38K2 Group
b7
b0
Index =0116 : Transmit/Receive buffer register (RXBUF/TXBUF) [address 003416]
Bit symbol
RXBUF/
–
TXBUF
Bit name
Function
At reset _{R W}
H/W S/W
The data received from an external bus is written here 0 – O O
at the rise timing of external write signal.
The data transmitted to an external bus is written here
at the timing of internal CPU write or memory write.
The receive buffer register (RXBUF) contents can be read out by reading to this address with the CPU. The data which the
CPU has written to this address is stored in the transmit buffer register (TXBUF).
However, do not perform write operation with the CPU to this address if the memory channel direction control bits of
memory channel operation mode register is “102” (transmit mode) and the memory channel status bits of EXB interrupt
source register are “012” or “102” (memory channel being operating).
Fig. 116 Index01[low]; Structure of Transmit/Receive buffer register
b7
00000
b0
Index =0216 : Memory channel operation mode register (MCHMOD) [address 003416]
Bit symbol
Bit name
MC_DIR
[1:0]
Memory channel direction
control bit
BURST
Burst bit
b7:b3
Not used
Function
At reset _{R W}
H/W S/W
b1b0
0 – OO
0 0 : Operation disabled
0 1 : Receive mode
1 0 : Transmit mode
1 1 : Do not set.
0 : Cycle mode (each byte transfer according to 0 – O O
assertion or negation)
1 : Burst mode (continuous transfer till the terminal
count)
Write “0” when writing.
– – OO
“0” is read when reading.
–: State remaining
Fig. 117 Index02[low]; Structure of Memory channel operation mode register
b7
b0
Index = 0316 : Memory address counter (MEMADL) [address 003416]
Bit symbol
IM_A
–
[7:0]
Bit name
Function
At reset _{R W}
H/W S/W
Register to set the low-order address of memory 0 – O O
channel operation beginning.
This contents are increased each time one memory
access ends.
Fig. 118 Index03[low]; Structure of Memory address counter
Rev.3.00 Oct 15, 2006 page 79 of 147
REJ03B0193-0300