MSM66P54 datasheet(21/46 Pages) OKI

21 / 46 page

¡ Semiconductor

MSM6679AL-110 Voice Recognition Processor

Name Tag Recording

To facilitate SD recognition, the MSM6679AL-110 supports recording and playback of name tags.

Name tags are used to confirm correct responses in SD recognition. For example, in a phone

dialer application, the user associates a “name” (which is recorded into memory) with a phone

number. The MSM6679AL-110 then plays back the name tag so that the user can verify that the

recognized phrase is the correct one.

The VRP stores names tags in memory using an ADPCM compression algorithm with 28 kbps

of speech. The length of a name tag is controlled with a command from the users host MCU

program. The maximum number of name tags possible is 61, but the actual number is dependent

upon record time and memory available. See the section on memory interface for more detail.

Audio Input Interface

A critical item for high-accuracy speech recognition is correct design of the audio input circuit.

A circuit with appropriate gain and frequency responses must be placed between the microphone

and MSM6679AL-110’s A/D input. Oki recommends input gain and a band pass filter with the

following characteristics:

• Four pole Chebyshev high-pass filter, 3 dB point at 225 Hz

• Dual-pole low-pass filter, 3 dB point at 4250 Hz

• Midband gain of 46 dB at 1000 Hz

The above gain and filter characteristics are obtained by using a rail-to-rail quad CMOS op-amp

and one-half supply rail splitter to bias the input signal at 1/2 VDD nominal.

The MSM6679AL-110 uses multiple analog inputs to improve sampling quality. An on-chip

analogy to digital (A/D) conversion unit transforms the analog signal to a digital data stream.

Audio Output Interface

The MSM6679AL-110 also provides the VOICEOUT1 PWM output. The MSM6679AL-110 uses

ADPCM to generate voice or sound-effect output. ADPCM represents an improvement over

conventional PCM techniques in that it adaptively changes the quantizer step (scale factor) to suit

the waveform being encoded. The result is more efficient memory usage with no loss of quality.

Careful selection of the components for internal and external output filters and amplifiers is

recommended. An incorrect choice would impair the original quality. This consideration equally

includes:

• Careful separation of analog and digital lines

• Grounding of analog lines at both ends

• Further adequate separation from high-speed digital circuits to avoid distortions thereof

Memory Interface

The memory control section manages RAM and/or ROM devices in two 64-Kbyte memory

spaces, in conjunction with internal memory for voice templates and working memory. Some

versions work with no external memory, some have some external RAM, some use only external

EPROM, and some use external memory in conjunction with both internal ROM and RAM. The

MSM6679AL-110 requires a minimum of 32 Kbytes SRAM and 16 Kbytes ROM.

The following table shows vocabulary sizes and playback facilities for various configurations.

MSM66P54 数据表(PDF) 21 Page - OKI electronic componets

MSM66P54 数据表(HTML) 21 Page - OKI electronic componets

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

数据表下载