7721 datasheet(14/577 Pages) RENESAS

14 / 577 page

7721 Group User’s Manual

vii

Table of contents

CHAPTER 15 WATCHDOG TIMER

15.1 Block description .............................................................................................................. 15-2

15.1.1 Watchdog timer .......................................................................................................... 15-3

15.1.2 Watchdog timer frequency select register .............................................................. 15-3

15.2 Operation description ...................................................................................................... 15-4

15.2.1 Basic operation .......................................................................................................... 15-4

15.2.2 Stop period ................................................................................................................. 15-6

15.2.3 Operation in Stop mode ........................................................................................... 15-6

15.3 Precautions for Watchdog timer ................................................................................... 15-7

CHAPTER 16 APPLICATION

16.1 Memory connection .......................................................................................................... 16-2

16.1.1 Memory connection model ........................................................................................ 16-2

16.1.2 How to calculate timing ............................................................................................ 16-4

16.1.3 Example of memory connection ............................................................................ 16-20

16.1.4 Example of I/O expansion ...................................................................................... 16-40

16.2 Examples of using DMA controller ............................................................................. 16-43

16.2.1 Example of Centronics interface configuration .................................................... 16-43

16.2.2 Example of stepping motor control ....................................................................... 16-48

16.2.3 Example of dynamic lighting for LED ................................................................... 16-53

16.3 Comparison of sample program execution rate ...................................................... 16-56

16.3.1 Differences depending on data bus width and software Wait ........................... 16-56

16.3.2 Comparison between software Wait (f(XIN) = 20 MHz) and software Wait + Ready (f(XIN) = 25 MHz) .... 16-58

APPENDIX

Appendix 1. Memory assignment of 7721 Group ............................................................... 17-2

Appendix 2. Memory assignment in SFR area ................................................................... 17-3

Appendix 3. Control registers ................................................................................................. 17-9

Appendix 4. Package outline ................................................................................................ 17-40

Appendix 5. Examples of handling unused pins ............................................................. 17-41

Appendix 6. Machine instructions ....................................................................................... 17-42

Appendix 7. Hexadecimal instruction code table ............................................................. 17-56

Appendix 8. Countermeasure against noise ...................................................................... 17-59

Appendix 9. 7721 Group Q & A ........................................................................................... 17-65

Appendix 10. Differences between 7721 Group and 7720 Group ................................. 17-79

Appendix 11. Electrical characteristics .............................................................................. 17-80

Appendix 12. Standard characteristics ............................................................................. 17-107

GLOSSARY

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