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541
CHAPTER 25 SOUND GENERATOR
25.2.4
Decrement Grade Register
The Decrement Grade register stores the reload value for the Decrement counter. They
are prepared to automatically decrement the stored value in the Amplitude Data
register. The register value is reloaded into the counter at Decrement counter underflow
and falling edge of tone signal.
■
Decrement Grade Register
When the DEC bit is "1" and the Decrement counter counts the number of tone pulses up to the reload
value, the stored value in the Amplitude Data register is decremented by 1(one) at the end of the tone cycle.
This operation realizes automatic de-gradation of the sound with fewer number of CPU interventions.
It should be noted that the number of the tone pulses specified by this register equals to "register value +1".
When the Decrement Grade register is set to "00
H
", the decrement operation is performed every tone cycle.
7
6
5
4
3
2
1
0
Initial value
X X X X X X X X
B
R/W R/W R/W R/W
R/W
R/W
R/W
R/W
H
003548
SGDR
D7 D6 D5 D4 D3 D2
D1 D0
bit
Address:
Summary of Contents for MB90390 Series
Page 2: ......
Page 4: ......
Page 17: ...xiii APPENDIX D List of Interrupt Vectors 690 INDEX 695 ...
Page 18: ...xiv ...
Page 132: ...104 CHAPTER 5 CLOCKS ...
Page 152: ...124 CHAPTER 6 CLOCK MODULATOR ...
Page 210: ...182 CHAPTER 11 TIME BASE TIMER ...
Page 218: ...190 CHAPTER 12 WATCHDOG TIMER ...
Page 264: ...236 CHAPTER 14 16 BIT RELOAD TIMER WITH EVENT COUNT FUNCTION ...
Page 274: ...246 CHAPTER 15 WATCH TIMER ...
Page 306: ...278 CHAPTER 17 DTP EXTERNAL INTERRUPTS ...
Page 338: ...310 CHAPTER 18 8 10 BIT A D CONVERTER ...
Page 364: ...336 CHAPTER 19 UART0 UART1 ...
Page 398: ...370 CHAPTER 20 UART2 UART3 Figure 20 5 2 ORE Set Timing Receive data RDRF ORE ...
Page 432: ...404 CHAPTER 20 UART2 UART3 ...
Page 482: ...454 CHAPTER 22 SERIAL I O ...
Page 560: ...532 CHAPTER 24 STEPPING MOTOR CONTROLLER ...
Page 582: ...554 CHAPTER 27 ROM MIRRORING MODULE ...
Page 632: ...604 CHAPTER 29 EXAMPLES OF SERIAL PROGRAMMING CONNECTION ...
Page 722: ...694 APPENDIX ...
Page 723: ...695 INDEX The index follows on the next page This is listed in alphabetic order ...
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