JPH0212417A - Microprocessor initialization guarantee system - Google Patents

Abstract

PURPOSE: To eliminate a watch dog timer by changing voltage on a reset terminal in a reset circuit and setting a micro processor to a resetting mode in response to the operation of a switch. CONSTITUTION: When a capacitor 17 is charged, the micro processor 11 becomes an initialization mode and the voltage of the input terminal 13 in the micro processor 11 is internally detected. Logic '0' in the input terminal 13 shows that a viewer operates the switch 24 or a television receiver is switched to an or off. Logic '1' in the input terminal 1 shows that the micro processor is in a mode state for waiting for the switch 24 to be turned off. When the switch 24 is turned off, the capacitor 17 discharges through a capacitor 19 and sets the micro processor 11 to the resetting mode during the time required for the capacitor 17 to execute recharging. Thus, the watch dog timer becomes unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates generally to the initialization of microprocessor microcomputers, and more particularly to a system that eliminates the need for separate and expensive watch timers. .

BACKGROUND OF THE INVENTION Microcomputer or microprocessor (hereinafter these terms are used interchangeably).

), bias voltages are applied to various components of the system, including the microprocessor or computer. The microprocessor enters an initialization routine in which the microprocessor's program counter is set to a calculated value of zero. The initialization routine defines and sets all initial conditions regarding the operation of the Mitalo processor. This initial condition involves resetting the microprocessor's internal logic circuitry to an initialized condition from which all further operations are performed. A common problem encountered with microprocessors is a lockout of normal operating functions that prevents complete completion of the initialization routine. Such lockouts can occur due to any one of several well-known causes. AC line glitches, software errors that create circular loops that the microprocessor cannot break out of, electrostatic discharge “ZAP”
) or an arc from the picture tube. The last problem frequently arises when microprocessors are used in television receivers.

The potential difficulty of lockouts has been recognized in the computer arts, and a proposed solution is the use of watchdog timers.

This type of timer monitors the state of the microprocessor and when the microprocessor is not properly initialized within a preselected maximum time period set by the watchdog timer, the watchdog timer initiates an initialization routine. Supplying power to start over makes the microprocessor work again to return to its previous state. If there is no permanent defect in the microprocessor or the device in which it is incorporated, the difficulties that caused the initial lockout generally no longer exist, and the microprocessor will be able to function properly with subsequent processing. Initialized.

Watchdog timers are very effective for this intended purpose. However, it suffers from a considerable disadvantage in that the large number of extra components required significantly increases the cost of the device containing the microprocessor.

This is particularly disadvantageous in highly competitive consumer products such as color television receivers, where reducing production costs is paramount. For these reasons, there is a need for an effective microprocessor initialization assurance system that eliminates the need for a watchdog timer, requires minimal additional components, and reduces cost. The present invention fulfills this need.

SUMMARY OF THE INVENTION A microprocessor initialization assurance system used in an electronic device including a microprocessor processor having a reset terminal 2 includes a switch. A reset circuit is provided between the reset terminal and the switch and changes the voltage on the reset terminal to place the microprocessor in a reset mode in response to actuation of the switch.

Embodiment In FIG. 1, a microprocessor initialization system 1
0 includes a microprocessor 111ft: having a reset terminal 12 and an input terminal 13. Oscillator 14
supplies a clock to the microprocessor 11. The first charge storage means includes a resistor 16 and a capacitor 17 connected in series between the + bias power supply and the ground. A reset terminal 12 of microprocessor 11 is responsive to a junction 18 of resistor 16 and capacitor 17. The second charge storage means includes a capacitor 1
9 and a resistor 21. An impedance such as resistor 22 is connected to junction point 2 between capacitor 19 and resistor 21.
3 and to ground via a normally open, momentarily closed switch 24.

Input terminal 13 of microprocessor 11 is connected to switch 24 by conducting means 26 through impedance means such as resistor 27 .

The switch 24 is provided in a keyboard (not shown) provided on the cabinet of the device in which the microprocessor initialization assurance system 10 is installed. When the invention is embodied in a television receiver, this key date is used by the viewer to provide various inputs such as turning the receiver on and off, channel selection, etc. In modern television sets, it is also used by the viewer to provide various interactive inputs that are provided to the microprocessor. In such a receiver, switch 24 acts as an on-off switch;
It is also identified as such on the key date. When the invention is embodied in a television set having remote control means, switch 24 can be operated as an on-off switch in response to a message from a hand-held remote control.

When power is applied to initialization system 10 and microprocessor 11, a bias voltage of V+ is applied to B+ bin 28 of microprocessor 11 and resistors 16 and 21. The reset terminal 2 of the microprocessor 11 is held in a reset state until the capacitor 17 is charged.

The charging time of capacitor 17 is as follows: resistor 16, capacitor 1
7. It is determined by the combination of resistor 21 and capacitor 19, and in the case of a television receiver, the entire photoelectric time can be selected to about 100 milliseconds. Once capacitor 17 is charged, microprocessor 11 enters an initialization mode and the voltage at input terminal 13 of microprocessor 11 is sensed internally. As will be explained below, the logic "'0#" at input terminal 13 indicates that the viewer can switch 24
indicates that the television receiver has been activated and that the television receiver is to be switched on or off. A logic "'1#" at input terminal 13 indicates that the microprocessor is in a mode waiting for switch 24 to close. When switch 24 closes, capacitor 17 discharges through capacitor 19 and capacitor 17 The microprocessor 11 is placed in reset mode for the time required for the microprocessor to recharge. Typically, the microprocessor resets in about 50 milliseconds.

Thus, an exemplary charging time of 100 milliseconds is long enough for a standard microprocessor to reset its internal counters, but short enough that the viewer will not notice it. Research has also shown that 100 milliseconds is approximately the amount of time the viewer holds the switch 24 closed, thus providing ample time for the microprocessor sensor 11 to reset. The ratio of capacitors 17 and 19 is therefore chosen such that capacitor 17 recharges before switch 24 opens again. Resistor 22 is switch 24
limit the flow of current through the Resistor 27 provides electrostatic discharge protection for input terminal 13 of microprocessor 11. This impedance is particularly important when the invention is used in television receivers where high energy discharges can occur.

Briefly, by supplying a + bias voltage, in operation when the television receiver is first turned on, the microprocessor 11 is in a reset state until the capacitor 17 is charged. When capacitor 17 is sufficiently charged, microprocessor 11 is initialized, input terminal 13 goes high, and microprocessor 1
1, preparations are made to close the switch 24. When the viewer closes switch 24, input terminal 13 goes low. This low condition is detected by the microprocessor 11 and indicates that the receiver should be turned on or off, both of which are the opposite of the current condition.

Also, when switch 24 is closed, capacitor 17 is discharged and microprocessor 11 is placed in a reset mode. Assuming the receiver is off, switch 24
When it opens again, the viewer releases the on-off key, so capacitor 17 is charged again and terminal 13 returns to its high state. Microprocessor 11 then enters an initialization routine.

Once microprocessor 11 successfully completes its initialization routine, a high condition at input terminal 13 is detected;
The microprocessor 11 turns on the television set. However, if one of the previously mentioned problems occurs and the microprocessor is unable to successfully complete its initialization routine, the high condition on input terminal 13 will not be detected and the television section will turn on. Not be left behind.

In this case, the viewer's typical reaction is to switch 24 again.
By pressing switch 24 again, capacitor 17 is discharged again, the microprocessor is placed in reset mode, and the initialization routine is repeated. Generally, if there are no permanent defects in the receiver, any problems that prevent the initialization routine from fully running will occur when the viewer presses switch 24 several times and the initialization routine runs completely and the television set is eliminated by the time it turns on. When the viewer closes switch 24 to turn off the television set, capacitor 17 discharges again and input terminal 13 goes low. A low condition on input terminal 13 is detected by microprocessor 11, which responds by turning off the television set. Meanwhile, the capacitor 17 is charged again, leaving the switch 24 closed again so that the Ii television set is then turned back on. Therefore, the combined operation of capacitors 17 and 19 and resistors 16 and 21 is the operation of a reset circuit that places the microprocessor in a reset mode in response to the closing of switch 24.

FIG. 2 is a flowchart showing how the present invention operates in a television receiver. In step 29, power is supplied, and in step 30, the microprocessor 11 and system node 1 in the system are connected.
- The wear point is set. At decision 31, the checksum is examined. The checksum is an 8-bit word stored in the microprocessor that is compared to an 8-bit word stored elsewhere in the system. An incorrect checksum indicates that power to the microprocessor has previously been lost and stored information has been lost or reduced. Judgment 31
If the checksum is incorrect, proceed to step 32, zero the power on-off bits, initialize the checksum and correct it for the next comparison, then proceed to steps 33 and 34, respectively, and step 36 The entire device is turned off and input from the keyboard is read until switch 24 is indicated to be pressed. If the receiver is turned off when the checksum is incorrect, the receiver will not turn on after a temporary interruption in power supply. Returning to decision 31, if the checksum is correct,
Proceed to decision 35 and check to see if the power bit is on. If it is on, step 33, 34
．． 36 and wait until switch 24 is closed again. If the power bit is not on in Stella 7'35, the process proceeds to step 37 to turn on the device, and then proceeds to step 38 to begin full execution of the main operating routine of the microprocessor 11.

In step 39, so that the comparison required in step 31 can be made when the system is reinitialized,
Checksum is remembered again.

The present invention has the advantage that it ensures that the microprocessor completely completes its initialization routine within a short period of time that is well tolerated by the viewer, and eliminates the need for expensive and complex watchdog timers. It is extremely useful.

[Brief explanation of the drawing]

FIG. 1 shows a preferred embodiment. FIG. 2 is a flowchart illustrating the operation of the preferred embodiment of FIG. 11...Microprocessor, 12...Reset terminal, 17...Capacitor, 19...Capacitor, 2
4...On-off switch. Figure 1

Claims (1)

[Claims] (1) A microprocessor initialization assurance system for an electronic operating device including a microprocessor having a reset terminal, the system comprising: an on-off switch; and a reset circuit disposed between the reset terminal and the switch. and includes a first charge storage means disposed between the reset terminal and the switch,
a reset circuit that maintains the reset terminal at a logic level necessary to operate the microprocessor; and a reset circuit that is disposed between the first charge storage means and the switch and temporarily places the microprocessor in a reset mode. a second charge storage means for discharging the first charge storage means when the switch is closed to set the microprocessor initialization assurance system.