38K2 Datasheet, PDF (71/151 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

38K2 Group
EXB Block Diagram
The block diagram of external bus interface (EXB) is shown below.
The external bus interface (EXB) consists of:
(1) External I/O interface part
(2) CPU interface part
(3) Internal memory interface part
(4) Transmit/Receive data buffer part
External MCU bus
P34/ExCS
P37/ExA0
P36/ExRD
P35/ExWR
P41/ExDACK/TxD
P42/ExTC/SCLK
P43/ExA1/SRDY
P33/ExINT
P40/ExDREQ/RxD
P10/DQ0/AN0–
P17/DQ7/AN7
External I/O interface
stt_sel
ExOE
Configuration
signal
Cch_WR
Cch_RD
TxB_RDY
RxB_RDY
CPU interface
External I/O
configuration
register
Index register
EXB interrupt
source enable register
CPU channel
controller
Decoder data selector
Memory channel
control
Memory channel
status
Mch_RD
Mch_WR
Mch_TC
Internal memory
interface
mRX_enb
mTX_enb
Memory channel
operation mode register
Memory address
counter
Memory address
Mch_req
FIFO_stt
Buf_WR
End address register
Memory channel
controller
MRDsel
Memory channel
transmit buffer control
Transmit/Receive data
buffer
Transmit buffer register
Receive buffer register
Request acknowledge
Memory read data
Memory write data
: Functions as normal ports just after reset.
Fig. 106 Block diagram of external bus interface (EXB)
Rev.3.00 Oct 15, 2006 page 71 of 147
REJ03B0193-0300