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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(X
IN
) = 20 MHz) and software Wait + Ready (f(X
IN
) = 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