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MICROPROCESSOR SIGNALING SCHEME WITH UNIQUE PUSH TO TALK

IP.com Disclosure Number: IPCOM000005464D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2001-Oct-10
Document File: 2 page(s) / 76K

Publishing Venue

Motorola

Related People

Larry Blair: AUTHOR

Abstract

Two-way moblle radlos today use mtcroprocessors to control radio functions. As shown in Figure 1 the control unit is often separated from the radio unit. Both units contain microprocessors. A scheme is needed to allow information to pass in both directions with the fewest possible wires and be compatible with existing push-to-talk schemes.

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Page 1 of 2

Volume 2 January 1982

@ mGtmR0i.A Technical Developments

MICROPROCESSOR SIGNALING SCHEME WITH UNIQUE PUSH TO TALK

By Larry Blair

   Two-way moblle radlos today use mtcroprocessors to control radio functions. As shown in Figure 1 the control unit is often separated from the radio unit. Both units contain microprocessors. A scheme is needed to allow information to pass in both directions with the fewest possible wires and be compatible with existing push-to-talk schemes.

   The signaling scheme requires three wires (see Figure 1). The data line transmits the information one bit at a time between the microprocessors. The clock line marks the beginning of each new data bit. The ground wire is the reference for the clock and data lines.

   As shown in Figure 2, the signaling scheme has a receive and a transmit mode. In the receive mode, three events occur. The data and clock lines are synchronized together. Eight bits of data are sent from the control unit to the mobile radio. Eight bits of data are sent from the radio to the control unit. The cycle repeats. In the transmit mode the data line is pulled low by the control unit microprocessor to start the data-clock synchronization, but the data line is held low by the control unit. After the time of three receive clock cycles, the radio begins transmittlng. The radio continues transmitting for as long as the data line is held low. When the control unit pulls the data line high, the radio dekeys and the radio microprocessor pull...