16 SOUND GENERATOR (SNDA)
S1C17M20/M21/M22/M23/M24/M25
Seiko Epson Corporation
16-11
TECHNICAL MANUAL (Rev. 1.0)
Bit 2
SINV
This bit selects an output pin drive mode.
1 (R/W): Normal drive mode
0 (R/W): Direct drive mode
For more information, refer to “Output Pin Drive Mode.”
Bits 1–0
MOSEL[1:0]
These bits select a sound output mode.
Table 16.6.3 Sound Output Mode Selection
SNDSEL.MOSEL[1:0] bits
Sound output mode
0x3
Reserved
0x2
Melody mode
0x1
One-shot buzzer mode
0x0
Normal buzzer mode
SNDA Control Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
SNDCTL
15–9 –
0x00
–
R
–
8
SSTP
0
H0
R/W
7–1 –
0x00
–
R
0
MODEN
0
H0
R/W
Bits 15–9 Reserved
Bit 8
SSTP
This bit stops sound output.
1 (W):
Stop sound output
0 (W):
Ineffective
1 (R):
In stop process
0 (R):
Stop process completed/Idle
The SNDCTL.SSTP bit is used to stop buzzer output in normal buzzer mode. After 1 is written, this
bit is cleared to 0 when the sound output has completed. Also in one-shot buzzer mode/melody mode,
writing 1 to this bit can forcibly terminate the sound output.
Bits 7–1
Reserved
Bit 0
MODEN
This bit enables the SNDA operations.
1 (R/W): Enable SNDA operations (The operating clock is supplied.)
0 (R/W): Disable SNDA operations (The operating clock is stopped.)
SNDA Data Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
SNDDAT
15 MDTI
0
H0
R/W –
14 MDRS
0
H0
R/W
13–8 SLEN[5:0]
0x00
H0
R/W
7–0 SFRQ[7:0]
0xff
H0
R/W
This register functions as a sound buffer. Writing data to this register starts sound output. For detailed information
on the setting data, refer to “Buzzer output waveform configuration (normal buzzer mode/one-shot buzzer mode)”
and “Melody output waveform configuration.”
Bit 15
MDTI
This bit specifies a tie or slur (continuous play with the previous note) in melody mode.
1 (R/W): Enable tie/slur
0 (R/W): Disable tie/slur
This bit is ignored in normal buzzer mode/one-shot buzzer mode.