ISD-ES502 Datasheet, PDF (3/7 Pages) Winbond – Demonstration Board

Play Button - The Play Button is pressed to begin playing the recorded message, which will play until it
ends or the Pause button is pressed. To resume playing press the Play Button again.
Button 9 - Voice Prompting Control - The system uses voice prompts recorded in the ISD5008 to assist
the user in operating the unit. If you're familiar with the operation, or just prefer the "sounds of silence,"
you can turn off the prompting feature by pressing the "9" key on the keypad. The normal mode is
initialized with the Voice Prompts turned on.
Button 0 - Set Sample Rate - The ISD5008 supports four data sampling rates. The ES502 retains in
memory the sampling rates used to record the outgoing message, duplex messages, and telephone
answering messages. When these messages are played back, the original sampling rate is restored.
This allows one, for example, to use a high sampling rate for the best quality Outgoing Message (OGM)
combined with a low sampling rate for the incoming message (ICM) to extend available recording time.
To demonstrate the sound modification capability, the Voice Notes function does not retain the original
rate, but uses the most recently set value. A message can therefore be recorded at one rate and played
back at another. Utility Filter Mode routes an external signal through the internal low-pass filter. The
cutoff frequency of the filter is determined by the most recently selected sample rate. When button 0 is
pressed, the = sign appears. The second key push should be 8,6,5, or 4, after which the phrase "8 KHz,"
"6.4 KHz," "5.3 KHz," or "4 KHz," will be spoken if voice prompts are enabled. All recording operations
from this point until the next change will be made at the selected rate.
The table below shows the filter setting for each sample rate. It should be noted that a full record and
playback cycle routes the audio through the filter twice. The resulting filter function therefore will be 6 dB
down at the indicated frequency.
Sample Rate 8.0 KHz 6.4 KHz 5.3 KHz 4 KHz
Filter cut off (- 6dB) 3.4 KHz 2.7 KHz 2.3 KHz 1.7 KHz
Button 1 - Set Volume² - The current volume level (0 through 7) appears on the 7-segment LED display
with the decimal point illuminated to indicate volume (rather than mode). The desired volume level is
entered with the keypad (note keys 8 and 9 default to 7) and the phrase "Volume is set" is spoken at the
new volume. The volume level is also indicated with the yellow bar graph on the map.
Functions-
Button 2 - Outgoing Message (OGM) - This button sets the demo up to record or play the Outgoing
Message used in the Telephone Answering Device demo. When in this mode, if the Play Button is
pressed, the previously recorded outgoing message will be played at its originally selected sample rate
(this sample rate defaults to 8 KHz in this location in the first version of the software). If the Record
Button is pressed, the user can record a message (maximum length 50 seconds at 8 KHz sampling rate)
using the microphone. In both cases, the map LEDs on the board will show the path used in a real
application to make a local recording using the microphone. During playback, the path shown is the one
used in an application to playback the recorded message over the telephone line. However, in order that
the user is able to hear the message, it is also routed through the volume control and speaker amplifier.
The new OGM will be used in the Telephone Answering Device prompt. If the message exceeds the
maximum available space, the recording will be truncated.
2 _{The volume selection is effective for most operations- this demonstrates its function, but is also a convenience for}
using the board.
ISD-ES502.PDF
02/10/06