CA1145496A - Microcomputer controlled key telephone line circuit - Google Patents
Microcomputer controlled key telephone line circuitInfo
- Publication number
- CA1145496A CA1145496A CA000361162A CA361162A CA1145496A CA 1145496 A CA1145496 A CA 1145496A CA 000361162 A CA000361162 A CA 000361162A CA 361162 A CA361162 A CA 361162A CA 1145496 A CA1145496 A CA 1145496A
- Authority
- CA
- Canada
- Prior art keywords
- key
- signal
- line
- response
- signaling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M9/00—Arrangements for interconnection not involving centralised switching
- H04M9/002—Arrangements for interconnection not involving centralised switching with subscriber controlled access to a line, i.e. key telephone systems
- H04M9/005—Arrangements for interconnection not involving centralised switching with subscriber controlled access to a line, i.e. key telephone systems with subscriber controlled access to an exchange line
- H04M9/006—Exchange line circuits
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- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Telephonic Communication Services (AREA)
- Monitoring And Testing Of Exchanges (AREA)
Abstract
TITLE
MICROCOMPUTER ? PHONE
?
ABSTRACT OF THE INVENTION
A microcomputer controlled key telephone line circuit for use in a key telephone. A micro-computer is used to sequentially and alternately scan the ringing lead and tip and ring leads associated with connected line circuits and A leads associated with connected telephone stations. The microcomputer operates in response to changes in the status of these leads to control the normal key telephone functions such as line pickup, hold and ringing current detec-tion, lamp illumination and tone signalling.
MICROCOMPUTER ? PHONE
?
ABSTRACT OF THE INVENTION
A microcomputer controlled key telephone line circuit for use in a key telephone. A micro-computer is used to sequentially and alternately scan the ringing lead and tip and ring leads associated with connected line circuits and A leads associated with connected telephone stations. The microcomputer operates in response to changes in the status of these leads to control the normal key telephone functions such as line pickup, hold and ringing current detec-tion, lamp illumination and tone signalling.
Description
TITLE
MICROCOMPUTER CONTROLLED KEY TELEPHONE
LINE CIRCUIT
BACKGROUND OF T~E INVENTION
(1) Field of the Invention The present invention relates to key tele-phones and more particuarly to a microcomputer con-trolled key telephone line circuit for use in a key telephone system.
MICROCOMPUTER CONTROLLED KEY TELEPHONE
LINE CIRCUIT
BACKGROUND OF T~E INVENTION
(1) Field of the Invention The present invention relates to key tele-phones and more particuarly to a microcomputer con-trolled key telephone line circuit for use in a key telephone system.
(2) Description of the Prior Art Key telephone common circuits have tradi-tionally been electromechanical in nature however recently electronic versions of these circuits have been patented. U.S. Patent 3,952,169 issued on April 20, 1976 to O. W. Vincent discloses the use of discrete logic and solid state switches to perform the key telephone functions. U.S. Patent 4,057,693 issued on November 8, 1977 to R. J. Angner however is more representative of the recent prior art. Angner uses a custom large scale integration chip to replace the logic which per~orms the key telephone common functions.
However this chip only controls the functions for one line and is not suitable for use in a self-contained key telephone system such as the Applicants' key tele-phone system. Bell Telephone Laboratories has recentlydeveloped a Com-Key 416 key telephone system which is similar to the Applicants' key telephone system.
However, in the Bell Com-Key system the common func-tions are provided by multiple custom large scale ~ .
,~
L?J~ 59c96 integration chips designed specifically to perform their limited purpose. Also these chips provide only logic control and interrupt functions, while tone ringers and clock circuitry are external to the large 5 scale integration chips. Also many of the required timing functions are performed by resistor-capacitor networks. Thus the Com-Key 416 key telephone system uses a large number of balky components to perform the key telephone line circuit functions.
Accordingly, it is an object of the present invention to provide a novel, low cost, minimum com-ponent technique of performing the key telephone line circuit functions.
SUMMARY OF THE INVENTION
The microcomputer controlled key telephone line circuit of the present invention provides the standard key telephone functions such as line pickup, hold and ringing detection, lamp illumination and tone signalling. The use of microcomputer control 20 to provide these functions is a novel, low cost and ; highly efficient method of providing the standard key telephone functions associated with a line circuit.
This circuit can be housed in a standard key telephone and operates to control two lines and multiple stations.
The circuit consists of a microcomputer connected between a ringing detection circuit, a line relay, loop relay, an A-lead detection gate, a lamp control gate and a common audible control gate for each of two lines. The microcomputer continuously 30 scans the ringing detection leads and the A-lead detec-tion leads to detect the presence of an incoming call or the origination of an outgoing call. The status of the A-lead indicates to the microcomputer either the operation of a line pickup key or the operation 35 of a hold key associated with one of the stations connected to the microcomputer. Upon detection of an incoming call the microcomputer will output a lamp flash signal to the lamp lead and a warble (two fre~
quency) tone to the common audible lead. Upon ' ~5~96 operation of a line pickup key the microcomputer will output a steady lamp signal to the lamp lead and re-move the warble tone from the common audible lead.
Upon operation of the hold key the microcomputer will output a lamp wink signal to the lamp lead and will apply a tone-on-hold signal to the tip and ring leads.
Thus the microcomputer provides the control ~unctions of the line circuit, and generates the timing signals and tone signals.
DESCRIPTION OE THE DRAWING
The single figure of the accompanying draw-ing is a circuit diagram of a microcomputer controlled key telephone line circuit in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the accompaning d~awing, the microcomputer controlled key telephone line circuit of the present invention is shown connected to line 1 and line 2. The common circuit includes the series combination of capacitor 101, resistor 102, zener diodes 103 and 104, and capacitor 105 connected across the tip and ring leads of line 1. Bridge 106 is also connected across the tip and ring leads of line 1 and is further connected to the series combination of line relay 107, contacts 12A and resistor 15.
Optical coupler 108 is connected across capacitor 105 and the base of phototransistor 108C is connected to the parallel combination of capacitor 109 and resistor 110. The emitter of phototransistor 108C
is connected to transistors 112 whose collector lead is connected to microcomputer 10. The emitter lead of transistor 112A is connected to microcomputer 10 via contact 107A. Similar circuitry is connected between line 2 and microcomputer 10. Loop relay 12 is connected to microcomputer 10 via gate 11. The A-lead associated with station one is connected to microcomputer 10 via gate 13 and a lamp associated with station one is connected to microprocessor 10 via gate 1~. The common audible lead, CAl, associated ~' .
59~
with station one is connected to gate 15 which is connected to microcomputer 10 via leads W and Cl.
Line relay 107 is further connected to microcomputer 10 via contacts 12B. Similar circuitry is connected between station two and microcomputer 10.
The operation of the microcomputer controlled key telephone line circuit o~ the present invention will be described with referenced to line 1 since line 2 operations are identical to those of line 1.
This circuit controls the standard key telephone func-tions such as line pickup, hold and ringing current detection, lamp illumination and tone signalling.
Microcomputer 10 sequentially and alternately scans the inputs from lines 1 and 2 every 10 milliseconds.
Thus it scans, for example, the A lead associated with line lt followed by the A lead associated with line 2, before scanning the next lead associated with line 1.
When an incoming call is connected to the line circuit, ringing current is applied to tbe tip and ring leads, Tl (CO) and Rl (CO). Zener diodes 103 and 104 breakdown to this ringing signal voltage and conduct current to optical coupler 108. Since there are dead periods, during the zero crossing transition, in a ringing cycle during which photo-diodes 108A and 108B do not conduct, capacitor 109 supplies t~e base current to phototransistor 108C
during these dead periods. Phototransistor 108C thus turns on in response to the ringing signal and causes transistors 112 to turn on and generate a logic 0 signal on lead Rl. Microcomputer 10 detects and validates this logic 0 signal and outputs a lamp ~lash signal (1 pulse per second, 50% duty cycle) to lead Ll via gate 14. Microcomputer 10 also applies a warble tone to lead W and enables gate 15 via lead Cl thereby applying the warble tone to common audible lead CAl. Upon operation of a line pickup key asso-ciated with station 1 an ~-lead signal will be applied to microcomputer 10 via gate 13. Microcomputer 10 ~5~
responds to the A-lead signal by outputting a steady lamp signal to lead Ll via gate 14. Microcomputer 10 also removes the common audible enable signal from lead Cl and the warble tone from lead W thereby re-moving the common audible signal from lead CAl. Line relay 107 operates in response to connection of the tip and ring leads, Tl (STA) and Rl (STA), to station 1. Line relay contacts 107A close in response to operation of relay 107 and apply a minus 24 volt signal (logic 0 to microcomputer 10 to indicate opera-tion of the line relay.
The operation of the microcomputer controlled key telephone line circuit is the same, as above de-scribed, for placing an outgoing call. In this case however ringing current is not initially detected and microcomputer 10 is in a scanning mode and ini-tially responds to operation of a line pickup key associated with station one, as detected on the Al lead via gate 13.
If the hold button associated with station 1 is depressed it will initially cause the Al lead to become deactivated. Microcomputer 10 will detect this state of the Al lead via gate 13 and apply a lamp wink signal to lead Ll via gate 14. The lamp wink signal is a 500 millisecond signal with a 90~
duty cycle providing a 450 millisecond period during which the lamp is on and a S0 millisecond period during which the lamp is off.
Microcomputer 10 als~ operates in response to deactivation of the Al lead to operate loop relay 12. Contacts 12A are closed in response to operation of loop relay 12 thereby connecting resistor 115 in shunt across the tip and ring leads. Resistor 115 provides a holding bridge across the tip and ring leads to present a loop to the central office via line 1 when complete depression of the hold key dis-connects sl:ation 1 from the tip and ring leads.
Operation of loop relay 12 also causes contacts 12 to close thereby connecting a tone on hold source _ ; ~
~s~
from microcomputer 10 to a winding of line relay 107.
Microcomputer 10 generates a continuous tone burst for 100 milliseconds every 10 seconds to provide a tone on hold signal. Since this signal is applied to a winding of loop relay 12 it is coupled on to the tip and ring winding of relay 12 thereby providing the tone on hold signal to line 1. If the hold condi~
tion of station 1 is removed by depressing a line pickup key, microcomputer 10 will detect the presence of an active A-lead via a gate 13 and release relay 12 therey removing the bridge resistor from the tip and ring leads and also disconnecting the tone on hold lead from line relay 107. Microcomputer 10 will further remove the lamp link signal from lead Ll and apply a steady lamp signal via gate 14. Also, if a call on-hold is abandoned by the held party, micro-computer 10 will detect the absence of loop current and after 450 milliseconds will remove the hold bridge thus dropping the connection.
Microcomputer 10 has 5 modes of operation, idle (on-hook), a lead timing, off-hook, on-hold, and ringing. During the idle mode microcomputer 10 scans A leads, Al and A2, and ringing leads, Rl and R2. Microcomputer 10 scans these leads once every 10 milliseconds and upon detection of an active A-lead it will operate in the A-lead timing mode while upon detection of an active ringing lead it will operate in the ringing mode. From the ringing mode of operation, the idle mode can be entered if the ringing signal was invalid and the A-lead timing mode can be entered if an A-lead becomes active in the ringing mode. From the A-lead timing mode the idle mode will be entered if the active A-lead was invalid while the off-hook mode will be entered upon detection of a valid A-lead signal. If the A-lead becomes in-active while in the off-hook mode of operation the on-hold mode will be entered and if the tip and ring leads become inactive while the A-lead is inactive microcomputer 10 will return to the idle mode of 5~9~i operation. If the A-lead becomes active in the on-hold mode of operation microcomputer 10 will return to the A-lead timing mode of operation.
A detailed description of these five modes of operation follows. The idle mode of operation is a supervisory state during which ringing leads and A-leads are continuously scanned once every 10 milliseconds to detect an incoming call via the ring-ing leads and origination of an outgoing call via the A-leads. As stated previously upon detection of an active A-lead representing an outgoing call origination, the A-lead timing mode will be entered while upon detection oE an active ringing lead repre-senting an incoming call the ringing mode of operation will be entered.
In the ringing mode of operation microcom-puter 10 will scan the active ringing lead once every 10 milliseconds and upon detection of a valid ringing signal represented by 125 milliseconds of continuous ringing signal microcomputer 10 will output a lamp flash signal to lead Ll. It will also output a warble tone to common audible lead CAl. If an invalid ring-ing signal had been detected as represented by less than 125 milliseconds of continuous ringing signal microcomputer 10 will reenter the idle mode of opera-tion. Thus the A-lead timing mode of operation is entered via detection of an active A-lead in the idle mode of operation in response to origination of an outgoing call and it is also entered via detection of an active A-lead in the ringing mode of operation.
The A-lead becomes active in either case in response to operation of a line pickup key which is operated either for call origination, or in response to lamp flash and common audible tone for an incoming call. -Xn the A-lead timing mode of operation micro-computer 1() continuously scans the A-lead once every 10 milliseconds and upon detection of a valid A-lead as represented by 50 milliseconds of a continuously active A-lead, microcomputer 10 will output a steady ~.~
, - ~-. : :
s~
lamp signal, remove the warble tone from the common audible lead and then enter the off-hook mode of operation. If the A-lead had been invalid as repre-sented by les~ than 50 milliseconds of a continuously active A-lead signal microcomputer 10 will reenter the idle state.
In the off-hook mode of operation microcom-puter 10 will continuously scan the A-lead and upon detection of an inactive A-lead for greater than 50 milliseconds while the tip and ring leads remain active, microcomputer 10 will enter the on-hold mode of operation. If the call becomes abandoned as repre-sented by the tip and ring leads becoming inactive within 50 milliseconds of the A-lead becoming inactive microcomputer 10 will reenter the idle mode of operation.
In the on-hold mode of operation if the A lead becomes active again for 20 milliseconds micro-computer 10 will reenter the A-lead timing mode of operation while if the tip and ring leads become in-active for 450 mllliseconds the microcomputer willreenter the idle mode of operation since the call was abandoned.
The microcomputer controlled key telephone line circuit of the present invention is controlled by microcomputer 10 in accordance with a program stored in its memory. A representative example of a microcomputer which can be adapted to the present invention is the Intel 8048. Microcomputers are well known and other comparable microcomputers could be adapted to the pxesent invention by those skilled in the art.
The microcomputer controlled key telephone line circuit of the present invention thus performs the standard key telephone functions of line pickup, hold detection, ringing current detection, lamp illu-mination and tone signalling under control of a micro computer. While the microcomputer controlled key telephone line circuit of the present invention can be connected to numerous stations only 2 stations . . .
.
~ ~ .
~S~6 g - were shown in the preferred embodiment since micro-computer 10 is shown connected to only 2 lines.
Additional lines and stations could be connected to microprocessor 10 since the capacity of such a system can be increased through use of microcomputers with additional processing capability.
It will be obvious to those skilled in the art that numerous modificatic>ns of the present inven-tion can be made without departing from the spirit of the invention which shall be limited only by the scope of the claims appended hereto.
- .
However this chip only controls the functions for one line and is not suitable for use in a self-contained key telephone system such as the Applicants' key tele-phone system. Bell Telephone Laboratories has recentlydeveloped a Com-Key 416 key telephone system which is similar to the Applicants' key telephone system.
However, in the Bell Com-Key system the common func-tions are provided by multiple custom large scale ~ .
,~
L?J~ 59c96 integration chips designed specifically to perform their limited purpose. Also these chips provide only logic control and interrupt functions, while tone ringers and clock circuitry are external to the large 5 scale integration chips. Also many of the required timing functions are performed by resistor-capacitor networks. Thus the Com-Key 416 key telephone system uses a large number of balky components to perform the key telephone line circuit functions.
Accordingly, it is an object of the present invention to provide a novel, low cost, minimum com-ponent technique of performing the key telephone line circuit functions.
SUMMARY OF THE INVENTION
The microcomputer controlled key telephone line circuit of the present invention provides the standard key telephone functions such as line pickup, hold and ringing detection, lamp illumination and tone signalling. The use of microcomputer control 20 to provide these functions is a novel, low cost and ; highly efficient method of providing the standard key telephone functions associated with a line circuit.
This circuit can be housed in a standard key telephone and operates to control two lines and multiple stations.
The circuit consists of a microcomputer connected between a ringing detection circuit, a line relay, loop relay, an A-lead detection gate, a lamp control gate and a common audible control gate for each of two lines. The microcomputer continuously 30 scans the ringing detection leads and the A-lead detec-tion leads to detect the presence of an incoming call or the origination of an outgoing call. The status of the A-lead indicates to the microcomputer either the operation of a line pickup key or the operation 35 of a hold key associated with one of the stations connected to the microcomputer. Upon detection of an incoming call the microcomputer will output a lamp flash signal to the lamp lead and a warble (two fre~
quency) tone to the common audible lead. Upon ' ~5~96 operation of a line pickup key the microcomputer will output a steady lamp signal to the lamp lead and re-move the warble tone from the common audible lead.
Upon operation of the hold key the microcomputer will output a lamp wink signal to the lamp lead and will apply a tone-on-hold signal to the tip and ring leads.
Thus the microcomputer provides the control ~unctions of the line circuit, and generates the timing signals and tone signals.
DESCRIPTION OE THE DRAWING
The single figure of the accompanying draw-ing is a circuit diagram of a microcomputer controlled key telephone line circuit in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the accompaning d~awing, the microcomputer controlled key telephone line circuit of the present invention is shown connected to line 1 and line 2. The common circuit includes the series combination of capacitor 101, resistor 102, zener diodes 103 and 104, and capacitor 105 connected across the tip and ring leads of line 1. Bridge 106 is also connected across the tip and ring leads of line 1 and is further connected to the series combination of line relay 107, contacts 12A and resistor 15.
Optical coupler 108 is connected across capacitor 105 and the base of phototransistor 108C is connected to the parallel combination of capacitor 109 and resistor 110. The emitter of phototransistor 108C
is connected to transistors 112 whose collector lead is connected to microcomputer 10. The emitter lead of transistor 112A is connected to microcomputer 10 via contact 107A. Similar circuitry is connected between line 2 and microcomputer 10. Loop relay 12 is connected to microcomputer 10 via gate 11. The A-lead associated with station one is connected to microcomputer 10 via gate 13 and a lamp associated with station one is connected to microprocessor 10 via gate 1~. The common audible lead, CAl, associated ~' .
59~
with station one is connected to gate 15 which is connected to microcomputer 10 via leads W and Cl.
Line relay 107 is further connected to microcomputer 10 via contacts 12B. Similar circuitry is connected between station two and microcomputer 10.
The operation of the microcomputer controlled key telephone line circuit o~ the present invention will be described with referenced to line 1 since line 2 operations are identical to those of line 1.
This circuit controls the standard key telephone func-tions such as line pickup, hold and ringing current detection, lamp illumination and tone signalling.
Microcomputer 10 sequentially and alternately scans the inputs from lines 1 and 2 every 10 milliseconds.
Thus it scans, for example, the A lead associated with line lt followed by the A lead associated with line 2, before scanning the next lead associated with line 1.
When an incoming call is connected to the line circuit, ringing current is applied to tbe tip and ring leads, Tl (CO) and Rl (CO). Zener diodes 103 and 104 breakdown to this ringing signal voltage and conduct current to optical coupler 108. Since there are dead periods, during the zero crossing transition, in a ringing cycle during which photo-diodes 108A and 108B do not conduct, capacitor 109 supplies t~e base current to phototransistor 108C
during these dead periods. Phototransistor 108C thus turns on in response to the ringing signal and causes transistors 112 to turn on and generate a logic 0 signal on lead Rl. Microcomputer 10 detects and validates this logic 0 signal and outputs a lamp ~lash signal (1 pulse per second, 50% duty cycle) to lead Ll via gate 14. Microcomputer 10 also applies a warble tone to lead W and enables gate 15 via lead Cl thereby applying the warble tone to common audible lead CAl. Upon operation of a line pickup key asso-ciated with station 1 an ~-lead signal will be applied to microcomputer 10 via gate 13. Microcomputer 10 ~5~
responds to the A-lead signal by outputting a steady lamp signal to lead Ll via gate 14. Microcomputer 10 also removes the common audible enable signal from lead Cl and the warble tone from lead W thereby re-moving the common audible signal from lead CAl. Line relay 107 operates in response to connection of the tip and ring leads, Tl (STA) and Rl (STA), to station 1. Line relay contacts 107A close in response to operation of relay 107 and apply a minus 24 volt signal (logic 0 to microcomputer 10 to indicate opera-tion of the line relay.
The operation of the microcomputer controlled key telephone line circuit is the same, as above de-scribed, for placing an outgoing call. In this case however ringing current is not initially detected and microcomputer 10 is in a scanning mode and ini-tially responds to operation of a line pickup key associated with station one, as detected on the Al lead via gate 13.
If the hold button associated with station 1 is depressed it will initially cause the Al lead to become deactivated. Microcomputer 10 will detect this state of the Al lead via gate 13 and apply a lamp wink signal to lead Ll via gate 14. The lamp wink signal is a 500 millisecond signal with a 90~
duty cycle providing a 450 millisecond period during which the lamp is on and a S0 millisecond period during which the lamp is off.
Microcomputer 10 als~ operates in response to deactivation of the Al lead to operate loop relay 12. Contacts 12A are closed in response to operation of loop relay 12 thereby connecting resistor 115 in shunt across the tip and ring leads. Resistor 115 provides a holding bridge across the tip and ring leads to present a loop to the central office via line 1 when complete depression of the hold key dis-connects sl:ation 1 from the tip and ring leads.
Operation of loop relay 12 also causes contacts 12 to close thereby connecting a tone on hold source _ ; ~
~s~
from microcomputer 10 to a winding of line relay 107.
Microcomputer 10 generates a continuous tone burst for 100 milliseconds every 10 seconds to provide a tone on hold signal. Since this signal is applied to a winding of loop relay 12 it is coupled on to the tip and ring winding of relay 12 thereby providing the tone on hold signal to line 1. If the hold condi~
tion of station 1 is removed by depressing a line pickup key, microcomputer 10 will detect the presence of an active A-lead via a gate 13 and release relay 12 therey removing the bridge resistor from the tip and ring leads and also disconnecting the tone on hold lead from line relay 107. Microcomputer 10 will further remove the lamp link signal from lead Ll and apply a steady lamp signal via gate 14. Also, if a call on-hold is abandoned by the held party, micro-computer 10 will detect the absence of loop current and after 450 milliseconds will remove the hold bridge thus dropping the connection.
Microcomputer 10 has 5 modes of operation, idle (on-hook), a lead timing, off-hook, on-hold, and ringing. During the idle mode microcomputer 10 scans A leads, Al and A2, and ringing leads, Rl and R2. Microcomputer 10 scans these leads once every 10 milliseconds and upon detection of an active A-lead it will operate in the A-lead timing mode while upon detection of an active ringing lead it will operate in the ringing mode. From the ringing mode of operation, the idle mode can be entered if the ringing signal was invalid and the A-lead timing mode can be entered if an A-lead becomes active in the ringing mode. From the A-lead timing mode the idle mode will be entered if the active A-lead was invalid while the off-hook mode will be entered upon detection of a valid A-lead signal. If the A-lead becomes in-active while in the off-hook mode of operation the on-hold mode will be entered and if the tip and ring leads become inactive while the A-lead is inactive microcomputer 10 will return to the idle mode of 5~9~i operation. If the A-lead becomes active in the on-hold mode of operation microcomputer 10 will return to the A-lead timing mode of operation.
A detailed description of these five modes of operation follows. The idle mode of operation is a supervisory state during which ringing leads and A-leads are continuously scanned once every 10 milliseconds to detect an incoming call via the ring-ing leads and origination of an outgoing call via the A-leads. As stated previously upon detection of an active A-lead representing an outgoing call origination, the A-lead timing mode will be entered while upon detection oE an active ringing lead repre-senting an incoming call the ringing mode of operation will be entered.
In the ringing mode of operation microcom-puter 10 will scan the active ringing lead once every 10 milliseconds and upon detection of a valid ringing signal represented by 125 milliseconds of continuous ringing signal microcomputer 10 will output a lamp flash signal to lead Ll. It will also output a warble tone to common audible lead CAl. If an invalid ring-ing signal had been detected as represented by less than 125 milliseconds of continuous ringing signal microcomputer 10 will reenter the idle mode of opera-tion. Thus the A-lead timing mode of operation is entered via detection of an active A-lead in the idle mode of operation in response to origination of an outgoing call and it is also entered via detection of an active A-lead in the ringing mode of operation.
The A-lead becomes active in either case in response to operation of a line pickup key which is operated either for call origination, or in response to lamp flash and common audible tone for an incoming call. -Xn the A-lead timing mode of operation micro-computer 1() continuously scans the A-lead once every 10 milliseconds and upon detection of a valid A-lead as represented by 50 milliseconds of a continuously active A-lead, microcomputer 10 will output a steady ~.~
, - ~-. : :
s~
lamp signal, remove the warble tone from the common audible lead and then enter the off-hook mode of operation. If the A-lead had been invalid as repre-sented by les~ than 50 milliseconds of a continuously active A-lead signal microcomputer 10 will reenter the idle state.
In the off-hook mode of operation microcom-puter 10 will continuously scan the A-lead and upon detection of an inactive A-lead for greater than 50 milliseconds while the tip and ring leads remain active, microcomputer 10 will enter the on-hold mode of operation. If the call becomes abandoned as repre-sented by the tip and ring leads becoming inactive within 50 milliseconds of the A-lead becoming inactive microcomputer 10 will reenter the idle mode of operation.
In the on-hold mode of operation if the A lead becomes active again for 20 milliseconds micro-computer 10 will reenter the A-lead timing mode of operation while if the tip and ring leads become in-active for 450 mllliseconds the microcomputer willreenter the idle mode of operation since the call was abandoned.
The microcomputer controlled key telephone line circuit of the present invention is controlled by microcomputer 10 in accordance with a program stored in its memory. A representative example of a microcomputer which can be adapted to the present invention is the Intel 8048. Microcomputers are well known and other comparable microcomputers could be adapted to the pxesent invention by those skilled in the art.
The microcomputer controlled key telephone line circuit of the present invention thus performs the standard key telephone functions of line pickup, hold detection, ringing current detection, lamp illu-mination and tone signalling under control of a micro computer. While the microcomputer controlled key telephone line circuit of the present invention can be connected to numerous stations only 2 stations . . .
.
~ ~ .
~S~6 g - were shown in the preferred embodiment since micro-computer 10 is shown connected to only 2 lines.
Additional lines and stations could be connected to microprocessor 10 since the capacity of such a system can be increased through use of microcomputers with additional processing capability.
It will be obvious to those skilled in the art that numerous modificatic>ns of the present inven-tion can be made without departing from the spirit of the invention which shall be limited only by the scope of the claims appended hereto.
- .
Claims (15)
1. A method of controlling the connection of a plurality of lines to a plurality of key tele-phones, including a visual signaling device, a plu-rality of line pickup keys associated with said plu-rality of lines, and a plurality of control leads employed to indicate the operation of said line pickup keys, said method comprising the steps of:
scanning each control lead in a predeter-mined periodic time;
detecting operation of said line pickup key;
signaling said visual signaling device in a first manner, in response to detection of operation of said line pickup key.
scanning each control lead in a predeter-mined periodic time;
detecting operation of said line pickup key;
signaling said visual signaling device in a first manner, in response to detection of operation of said line pickup key.
2. The method of claim 1, wherein said lines are employed to transmit a ringing signal, said key telephones further including an audible signaling device, a hold key, said control leads further em-ployed to indicate the operation of said hold key, said method further comprising the steps of:
scanning each line in a predetermined peri-odic time;
detecting said ringing signal;
signaling said audible signaling device in response to detection of said ringing signal;
signaling said visual signaling device in a second manner, in response to detection of said ringing signal; and inhibiting said signaling of said audible signaling device in response to detection of operation of said line pickup key.
scanning each line in a predetermined peri-odic time;
detecting said ringing signal;
signaling said audible signaling device in response to detection of said ringing signal;
signaling said visual signaling device in a second manner, in response to detection of said ringing signal; and inhibiting said signaling of said audible signaling device in response to detection of operation of said line pickup key.
3. The method of claim 2, wherein: said lines further employed to transmit a loop signal, said method further employed the steps of:
detecting operation of said hold key;
detecting said loop signal;
signaling said visual signaling device, in a third manner, in response to detection of said loop signal and operation of said hold key; and maintaining said loop current during the duration of the operation of said hold key in response to detection of said loop signal and operation of said hold key.
detecting operation of said hold key;
detecting said loop signal;
signaling said visual signaling device, in a third manner, in response to detection of said loop signal and operation of said hold key; and maintaining said loop current during the duration of the operation of said hold key in response to detection of said loop signal and operation of said hold key.
4. The method of claim 3 further including the steps of:
detecting release of said hold key;
inhibiting said signaling in said third manner in response to detection of release of said hold key; and inhibiting maintaining of said loop current, in response to detection of release of said hold key.
detecting release of said hold key;
inhibiting said signaling in said third manner in response to detection of release of said hold key; and inhibiting maintaining of said loop current, in response to detection of release of said hold key.
5. The method of claim 3 further including the step of:
signaling said line in response to detection of said loop signal and operation of said hold key.
signaling said line in response to detection of said loop signal and operation of said hold key.
6. The method of claim 4 further including the step of:
inhibiting the signaling of said line in response to said detection of release of said hold key.
inhibiting the signaling of said line in response to said detection of release of said hold key.
7. The method of claim 2 further including the step of:
determining validity of said ringing signal by timing duration of said ringing signal for a pre-determined time.
determining validity of said ringing signal by timing duration of said ringing signal for a pre-determined time.
8. The method of claim 1 further including the step of:
determining validity of operation of said line pickup key by timing duration of operation of said line pickup key for a predetermined time.
determining validity of operation of said line pickup key by timing duration of operation of said line pickup key for a predetermined time.
9. The method of claim 1 further including the steps of:
detecting release of said line pickup key;
and inhibiting said signaling of said visual signaling device in said first manner, in response to detection of release of said line pickup key.
detecting release of said line pickup key;
and inhibiting said signaling of said visual signaling device in said first manner, in response to detection of release of said line pickup key.
10. A microcomputer controlled key telephone line circuit for use with a key telephone system in-cluding a plurality of lines, a plurality of key tele-phones, said lines employed to transmit a ringing voltage and a loop signal, said key telephones in-cluding a visual signaling device, an audible signal-ing device, a hold key, a plurality of line pickup keys associated with said plurality of lines, a plu-rality of control leads employed to indicate operation and release of said associated line pickup key and said hold key, said line circuit comprising:
ringing detection means connected to said plurality of lines operated in response to said ring-ing signals to generate a ringing signal;
scanning means connected to said ringing detection means, to said lines and to said control leads, said scanning means operated to scan said lines and said control leads in a predetermined periodic time, said scanning means further operated to detect said ringing signal, said loop signal, operation of said line pickup key and said hold key;
signaling means connected to said scanning means, to said visual signaling device, said audible signaling device and said line, operated in response to detection of operation of said line pickup key to signal said visual signal device, in a first man-ner, further operated in response to said detected ringing signal to signal said visual signaling device, in a second manner, and to signal said audible signal-ing device, and further operated in response to detec-tion of operation of said hold key to signal said visual signaling device in a third manner and to generate a bridging signal; and bridging means connected to said line and said signaling means, operated in response to said bridging signal to bridge said line.
ringing detection means connected to said plurality of lines operated in response to said ring-ing signals to generate a ringing signal;
scanning means connected to said ringing detection means, to said lines and to said control leads, said scanning means operated to scan said lines and said control leads in a predetermined periodic time, said scanning means further operated to detect said ringing signal, said loop signal, operation of said line pickup key and said hold key;
signaling means connected to said scanning means, to said visual signaling device, said audible signaling device and said line, operated in response to detection of operation of said line pickup key to signal said visual signal device, in a first man-ner, further operated in response to said detected ringing signal to signal said visual signaling device, in a second manner, and to signal said audible signal-ing device, and further operated in response to detec-tion of operation of said hold key to signal said visual signaling device in a third manner and to generate a bridging signal; and bridging means connected to said line and said signaling means, operated in response to said bridging signal to bridge said line.
11. A microcomputer controlled key telephone line circuit as claimed in claim 10, wherein there is further included:
line signaling means connected to said lines and to said signaling means; said signaling means further operated in response to detection of operation of said hold key to generate a hold signal, and said line signaling means operated to couple said hold signal to said line.
line signaling means connected to said lines and to said signaling means; said signaling means further operated in response to detection of operation of said hold key to generate a hold signal, and said line signaling means operated to couple said hold signal to said line.
12. A microcomputer controlled key telephone line circuit as claimed in claim 10, wherein there is further included:
timing means connected to said scanning means operated in response to detection of said ring-ing signal, said loop signal, operation of said line pickup key and operation of said hold key, to deter-mine the validity of said signals by timing the dura-tion of said signals for predetermined times.
timing means connected to said scanning means operated in response to detection of said ring-ing signal, said loop signal, operation of said line pickup key and operation of said hold key, to deter-mine the validity of said signals by timing the dura-tion of said signals for predetermined times.
13. A microcomputer controlled key tele-phone line circuit as claimed in claim 10, wherein:
said scanning means comprise a microcomputer.
said scanning means comprise a microcomputer.
14. A microcomputer controlled key tele-phone line circuit as claimed in claim 10, wherein:
said signaling means comprise a microcomputer.
said signaling means comprise a microcomputer.
15. A microcomputer controlled key tele-phone line circuit as claimed in claim 12, wherein:
said timing means comprise a microcomputer.
said timing means comprise a microcomputer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US8158279A | 1979-10-03 | 1979-10-03 | |
| US81,582 | 1979-10-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1145496A true CA1145496A (en) | 1983-04-26 |
Family
ID=22165069
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000361162A Expired CA1145496A (en) | 1979-10-03 | 1980-09-26 | Microcomputer controlled key telephone line circuit |
Country Status (3)
| Country | Link |
|---|---|
| BE (1) | BE884368A (en) |
| CA (1) | CA1145496A (en) |
| IT (1) | IT1132808B (en) |
-
1980
- 1980-07-18 BE BE2/58656A patent/BE884368A/en not_active IP Right Cessation
- 1980-09-26 CA CA000361162A patent/CA1145496A/en not_active Expired
- 1980-09-29 IT IT24996/80A patent/IT1132808B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| IT1132808B (en) | 1986-07-09 |
| IT8024996A0 (en) | 1980-09-29 |
| BE884368A (en) | 1980-11-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |