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22 HW Processor (HWP) and Sound
Output (SDAC2)
22.1 Overview
HWP is a functional block having the "Sound Play" and "Memory Check" functions. It can work without any CPU
resources by only issuing a command. SDAC2 converts the sound data generated by the HWP into PWM signals
and outputs them to an external audio amplifier or an external amplifier circuit composed of discrete parts. The fea-
tures of the HWP are listed below.
Sound Play function
• EPSON high quality and high compression algorithm (EOV: EPSON Original Sound Format)
- Sampling Frequency: 15.625 kHz
- Bitrate:
• Multi-channel mixer
• Playback speed conversion (channel 0)
- When using the speed conversion function alone, playback speed can be converted from 75% to 125% in 5%
steps.
- When using in combination with the pitch conversion function, playback speed can be converted from 85%
to 115% in 5% steps.
• Playback pitch conversion (channel 0)
- When using the pitch conversion function alone, playback pitch can be converted from 75% to 125% in 5%
steps.
- When using in combination with the speed conversion function, playback pitch can be converted from 90%
to 110% in 5% steps.
• A silent period is inserted between phrases. Gapless play can also be selected.
• Sequential playing of multiple sound files
• External QSPI-Flash* supported for storing sound data
Memory Check function
• Embedded RAM check (read/write check algorithm or March-C algorithm)
• Embedded Flash check (checksum or CRC algorithm)
• External QSPI-Flash* check (checksum or CRC algorithm)
* Supports only QSPI Flash memories with XIP (eXecute-In-Place) mode.
Figure 21.1.1 shows the HWP configuration.
Item
Sound Play function EOV play
Sound channel
Speed conversion
Pitch conversion
Simultaneous speed
and pitch conversion
Sound output circuit
Gapless play
Buzzer output
Memory Check function
S1C31D41 TECHNICAL MANUAL
(Rev. 1.1)
16/24 kbps
* See Table 21.1.1.
Table 22.1.1 HWP Channel Configuration of S1C31D41
Sampling frequency: 15.625 kHz
Bitrate:
2 channels
75% to 125% (5% steps)
75% to 125% (5% steps)
Speed: 85% to 115% (5% steps)
Pitch:
90% to 110% (5% steps)
* Channel 0 only
SDAC2
Available
Available
Available
Seiko Epson Corporation
22 HW Processor (HWP) and Sound Output (SDAC2)
* See Table 21.1.1.
S1C31D41
16/24 kbps
* Channel 0 only
* Channel 0 only
22-1
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