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Analogue output
The analogue output is on Pin 17 and 18 where the speaker is connected
Power
The 3V is supplied on Pin 19 and Ground on pin 20
Barcode scanner (optional)
Whenever the barcode scanner has a valid information a BEEP information will be generated
by the scanner and send via pin4 of CN501 and forwarded to pin 24 of IC 302 this BEEP will
be transferred to the speaker in the SpeechMike
Where the customer will here this information
Digital Mute Circuit
IC 303 is managing the MUTE function on the Digital output of the IC 302.
The MUTE output is triggered whenever a key button is pressed.
Important is that MUTE should only be activated after a complete Byte is transferred. The
length of a byte is defined by the Frame Clock so the Frame Clock signal (positive edge) on
pin 2 will be used to activate deactivate the MUTE (H) which is supplied to pin 1 of IC303.
This results than to a (H) signal on the output (Pin4) of the IC.
TS 301 on the output of IC 303 gets a (H) signal on the basis which leads to a (L) signal on
the collector and MUTE the signal via resistor R342.
Barcode scanner (optional)
Whenever the barcode scanner has a valit information a BEEP information will be generated
by the scanner and send via pin4 of CN501
10.3 Micro controller IC101
The Micro controller IC101 is managing the complete SpeechMike the required Firmware is
stored in the EE-Prom IC102.
Power on
Connecting the device to the USB port the device is powered.
The Reset IC101 (pin 9) is triggered by R105 and C104 to guarantee a regular start up of the
SpeechMike.The tact frequency is made out of the 6MHz Crystal connected to pin46 and pin
47.During start-up of the SpeechMike the Firmware is transferred via the IIC bus into the
micro controller. Micro controller checks by the help of a checksum the validity of the FW.
FW Update Mode
The firmware update mode is using above procedure in the following way.
Te Firmware is transferred via the IIC bus into the micro controller IC101. Micro controller
checks first id the 2 FW upgrade buttons are pressed if this is the case the Software will
destroy the Checksum, which leads to an invalid checksum. In case the Micro controller has
an invalid checksum it switches over to get a valid FW via the USB.
Once the set has started the main activity is to receive the audio streams from IC102 via pin
36 CDATI and format them to a valid USB information which will be send via the USB bus to
the PC
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