Table of Contents
Advertisement
CHAPTER 28 SOUND GENERATOR
28.2.5
Decrement Grade Register (SGDRn)
The Decrement Grade Register (SGDRn) stores the reload value for the Decrement
counter. It automatically decrements the reload value of the Amplitude Data register to
reduce the frequency of interrupts. The register value is reloaded into the counter at
Decrement counter underflow and falling edge of tone signal.
■ Decrement Grade Register (SGDRn)
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 degradation 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", the decrement operation is performed every tone cycle.
718
7
6
5
4
3
2
1
D7 D6 D5 D4 D3 D2
D1 D0
R/W R/W R/W R/W
R/W
R/W
R/W R/W
MB96300 Super Series Hardware Manual
0
SGDR
Initial value
X X X X X X X X
B
Advertisement
Table of Contents
