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Browse Prior Art Database

ENHANCED TIME DOMAIN OPTION RECOGNITION SCHEME

IP.com Disclosure Number: IPCOM000007725D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2002-Apr-17
Document File: 3 page(s) / 133K

Publishing Venue

Motorola

Related People

Joseph PatiƱo: AUTHOR

Abstract

One line Recognition schemes that use a peri- odic time base to determine an option select type are presently limited in their use because ofthe need to quickly determine the option type and because of all the part tolerances involved. A typical applica- tion of this would be an astable 555 timer in the accessory that is being monitored by the radio to determine its distinct duty cycle and therefore its distinct option type. In order for the option select scheme to be useful, it is preferable that the worst option type be repeated at least six times per sec- ond, so that the microprocessor can read at least two successive duty cycles within one third second.

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MO7VROLA Technical Developments

8

ENHANCED TIME DOMAIN OPTION RECOGNITION SCHEME

by Joseph Patitio

  One line Recognition schemes that use a peri- odic time base to determine an option select type are presently limited in their use because ofthe need to quickly determine the option type and because of all the part tolerances involved. A typical applica- tion of this would be an astable 555 timer in the accessory that is being monitored by the radio to determine its distinct duty cycle and therefore its distinct option type. In order for the option select scheme to be useful, it is preferable that the worst option type be repeated at least six times per sec- ond, so that the microprocessor can read at least two successive duty cycles within one third second.

This is fast enough that recognition is transparent to the user and is therefore acceptable. Because of

the tolerances involved with the associated resistors and capacitor, this approach realistically allows for five distinct option types (refer to Table 1). This inven- tion allows the radio the expanded capability to select up to nine option select types (refer to Table 2) or roughly a 2X improvement without sacrificing any functionality. This is accomplished by not just monitoring the total duty cycle but the separate rise and fall times associated with that duty cycle. By accomplishing this expanded option select capabil- ity with one line this invention replaces the stand- ard 2 I/O pin connections on the universal connec- tor and therefore eliminates one of the universal connector I/O and its associated static protection and filtering.

TABLE 1 existing capability by counting total cycle time = 5 distinct states

Cl fixed at0.1 !J f +I- 20%

Rb t2min 12 t2ma.x Ra Urnin 11 t1max ~(tl+qllax seconds seconds seconds n+i-5% seconds seconds seconds seconds seconds

10,000 0.001 0.001 0.001 100,000 0.006 0.006 0.010 0.010 10,000 0.001 0.001 0.001 270,000 0.015 0.019 0.024 0.025 10,000 0.001 0.001 0.001 550,000 0.029 0.039 0.049 0.050 10,000 0.001 0.001 0.001 1,030.000 0.055 0.072 0.091 0.092 10,000 0.001 0.001 0.001 1.630,000 0.097 0.126 0.161 0.162

TABLE 2 Proposed capability by counting rise and fall cycle times separately = 9 distinct states

Cl fixed atl.0 pf+/- 20%

Rb R +I- 5%

12 -%5 seconds

12 t2 +5% seconds seconds

Ra R +I- 5%

11 -5% 11 seconds seconds

11 +5% seconds

Z(tl+t2)max seconds

7,000 0.004 0.005 0.006 500 0.004 0.005 0.007 0.013 7,000 0:004 0.005 0.006 36,000 0.024 0.031 0.039 0.045 7,000 0.004 0.005 0.006 100,0b0 0.056 0.074 0.093 0.100 20,000 0.011 0.014 0.017 500 0.011 0.014 0.016 0.035 20,000 0.011 0.014 0.017 36,000 0.031 0.040 0.051 0.066 20,000 0.011 0.014 0.017 100,000 0.063 0.063 0.105 0.122 42,000 0.022 0.02s 0.037 500 0.022 0.029 0.037 0.074 42,000 0.022 0.029 0.037 36,000 0.042 0.055 0.070 0.107 42,000 0.022 0.0...