Chapter 17 Sound Generator; Sound Generator Function - NEC mPD780852 Series Preliminary User's Manual

17.1 Sound Generator Function

The sound generator has the function to sound the buzzer from an external speaker, and the following signal
are output.
• Basic cycle output signal
The signal is a buzzer signal with a variable frequency. By setting bits 0 to 2 (SGCL0 to SGCL2) of the sound
generator control register (SGCR), the signal in a range of 0.12 to 4.0 kHz can be output (when f
The amplitude of the 7-bit-resolution PWM signal can be varied to enable control of the buzzer sound volume.
Figure 17-1 shows the sound generator block diagram and Figure 17-2 shows the concept of basic cycle output
signal SGO.
SGCL0
f 1/2
X
PWM amplitude
4
SGBR3 SGBR2 SGBR1 SGBR0
Sound generator buzzer
control register (SGBR)
Figure 17-2. Concept of Basic Cycle Output Signal SGO
Basic cycle output SGO

CHAPTER 17 SOUND GENERATOR

Figure 17-1. Sound Generator Block Diagram
Internal bus
TCE SGCL2 SGCL1 SGCL0
f f
SG1 SG2
5-bit counter
Comparator
S
Q
Comparator R
7
SGAM6 SGAM5 SGAM4 SGAM3 SGAM2 SGAM1 SGAM0
Sound generator amplitude
register (SGAM)
Internal bus
Preliminary User's Manual U14581EJ3V0UM00
Sound generator control register (SGCR)
2
Clear
1/2
P61 output
latch
= 8.38 MHz).
X
SGO/P61
PM61
Port mode
register 6 (PM6)
223