Renesas F-ZTAT H8S/2132F, Руководство пользователя

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Section 4 Example Use of User System
Rev. 2.00 Dec 13, 2004 page 81 of 82
REJ05B0520-0200
4.1.2 Example I/O Port Switching Circuit
When writing with the H8S/2144F in boot mode, P90 to P92 must be set to High. Therefore, if the
user system uses P90 to P92 as input ports, the user system must switch the usage of these ports
between its own usage and their use as boot mode setting pins. If they are used as output ports,
P90 to P92 must be pulled up on the user system.
Table 4.2 shows example I/O port switching circuits. In these examples, P90 to P92 are set High
by the user system without their being connected to I/O0 to I/O2 on the adapter board. In the
example circuits for using P90 to P92 as input ports, P90 to P92 are set High if MD0 is Low. (To
reset and start boot mode, MD0 and MD1 are set Low and P90 to P92 are set High.) In the
example circuits for using P90 to P92 as output ports, P90 to P92 must be pulled up and set High.
Table 4.2 Example I/O Port Switching Circuits
Target Use of
P90 to P92
Example Circuit Description of Operation
Used as
input ports
by user
system
VCC VCC VCC VCC
H8S/2144F
HC126
User system I/O
Adapter board
connector
MD0
P91
P90
P92
MD0
Switches the target use of P90 to
P92 according to level of MD0 pin.
1. MD0 = High (normal operation)
P90 to P92 used as input ports.
2. MD0 = Low (boot mode)
P90 to P92 used as boot mode
setting pins.
P90 to P92 = High.
Used as
output ports
by user
system
VCC VCC VCC
H8S/2144F
User system I/O
Adapter board
connector
MD0
P90
P91
P92
MD0
1. Normal operation
P90 to P92 used as output
ports.
2. Boot mode
P90 to P92 used as boot mode
setting pins.
P90 to P92 = High
Note: The sample circuit above is for the case where the H8S/2144F is used in mode 3 in normal
operation. If using the H8S/2144F in mode 2 in normal operation, monitor the state of the
MD1 pin and switch the usage of P90 to P92.