INPUT/OUTPUT PINS
3–4
7751 Group User’s Manual
3.1.2 Port register
Data is input/output to/from externals by writing/reading data to/from the port register. The port register
consists of a port latch which holds the output data and a circuit which reads the pin state. Each bit of the
port register corresponds one for one to each pin of the microcomputer. Figure 3.1.3 shows the structure
of the port Pi (i = 0 to 8) register.
●
When outputting data from programmable I/O ports set to output mode
➀
By writing data to the corresponding bit of the port register, the data is written into the port latch.
➁
The data is output from the pin according to the contents of the port latch.
By reading the port register of a port set to output mode, the contents of the port latch is read out,
instead of the pin state. Accordingly, the output data is correctly read without being affected by an
external load. (Refer to Figures 3.1.4 and 3.1.5.)
●
When inputting data from programmable I/O ports set to input mode
➀
The pin which is set to input mode enters the floating state.
➁
By reading the corresponding bit of the port register, the data which is input from the pin can be
read out.
By writing data to the port register of a programmable I/O port set to input mode, the data is only
written into the port latch and is not output to externals. The pin retains floating.
3.1 Programmable I/O ports
Содержание 7700 FAMILY
Страница 2: ...MITSUBISHI 16 BIT SINGLE CHIP MICROCOMPUTER 7700 FAMILY 7751 SERIES 7751 Group User s Manual...
Страница 11: ...Table of Contents viii 7751 Group User s Manual MEMORANDUM...
Страница 12: ...CHAPTER 1 DESCRIPTION 1 1 Performance overview 1 2 Pin configuration 1 3 Pin description 1 4 Block diagram...
Страница 48: ...CHAPTER 3 INPUT OUTPUT PINS 3 1 Programmable I O ports 3 2 I O pins of internal peripheral devices...
Страница 157: ...TIMER B 6 28 7751 Group User s Manual 6 5 Pulse period pulse width measurement mode MEMORANDUM...
Страница 245: ...7751 Group User s Manual 8 36 A D CONVERTER Precautions when using A D converter MEMORANDUM...
Страница 246: ...CHAPTER 9 WATCHDOG TIMER 9 1 Block description 9 2 Operation description 9 3 Precautions when using watchdog timer...
Страница 254: ...CHAPTER 10 STOP MODE 10 1 Clock generating circuit 10 2 Operation description 10 3 Precautions for Stop mode...
Страница 260: ...CHAPTER 11 WAIT MODE 11 1 Clock generating circuit 11 2 Operation description 11 3 Precautions for Wait mode...
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Страница 289: ...CONNECTION WITH EXTERNAL DEVICES 12 4 Hold function 7751 Group User s Manual 12 24 MEMORANDUM...
Страница 290: ...CHAPTER 13 RESET 13 1 Hardware reset 13 2 Software reset...
Страница 302: ...CHAPTER 14 CLOCK GENERATING CIRCUIT 14 1 Oscillation circuit example 14 2 Clock...
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Страница 359: ...ELECTRICAL CHARACTERISTICS 7751 Group User s Manual 15 52 MEMORANDUM 15 15 Testing circuit for ports P0 to P8 1 and E...
Страница 360: ...CHAPTER 16 STANDARD CHARACTERISTICS 16 1 Standard characteristics...
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Страница 366: ...CHAPTER 17 APPLICATIONS 17 1 Memory expansion...
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Страница 406: ...CHAPTER 18 PROM VERSION 18 1 EPROM mode 18 2 Usage precaution...
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Страница 418: ...CHAPTER 19 FLASH MEMORY VERSION 19 1 Parallel input output mode 19 2 Serial input output mode...
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Страница 489: ...APPENDIX 7751 Group User s Manual 20 38 Appendix 6 Hexadecimal instruction code table...
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Страница 536: ...GLOSSARY...
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