JP3070833B2 - Battery level monitoring method for portable information terminals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for monitoring the remaining battery level of a portable information terminal, and more particularly to a method for monitoring the remaining battery level of a portable information terminal such as a palm-top pen input computer and a notebook personal computer.

[0002]

2. Description of the Related Art In a portable information terminal, an operation power supply having a limited power such as a battery is used. Therefore, it is important to monitor the remaining power of the operation power supply and to know the remaining power. As a conventional method of measuring the remaining battery level, when a coke-based lithium-ion battery is used as an operating power source, the battery voltage under a certain constant load is measured, and the remaining battery capacity is calculated from the voltage value. He was taking a guesswork. The measurement of the battery voltage is performed by, for example, A / D (Analog / Digi) as disclosed in the conventional example of Japanese Utility Model Laid-Open No. 5-47871.
tal) converter.

However, in the current portable information terminal,
A multitask OS (Op
A plurality of tasks are run on an erating system to simultaneously perform a plurality of processes. In such a multitask OS, since the amount of a task changes greatly every moment, a CPU (Central P
The processing amount at the processing unit also changes greatly with time. When running a multitasking OS,
Since the amount of tasks changes with time, it is difficult to make the power consumption of the CPU constant.

[0004] Therefore, in order to measure the remaining battery level, it is necessary to provide a multitask OS with a mode in which only one task that keeps the power consumption of the CPU constant is operated. This is because the CP that accounts for the majority of the power consumption of portable information terminals
This is because by making the power consumption of U constant, it is possible to make the load of the lithium ion battery which is the operation power supply constant, and to estimate the remaining battery level by measuring the voltage of the lithium ion battery at that time.

FIG. 4 is a circuit diagram of a main part showing an example of a conventional portable information terminal. This portable information terminal includes a lithium ion battery 1 as an operation power supply, a CPU 2 as a central processing unit, a peripheral circuit 3 for input / output such as communication, key input, and display, and an A / D converter for measuring a battery voltage. 6 and a main memory 7 in which a multitask OS (not shown), a battery remaining amount monitoring task 21 and the like are stored.

The CPU 2 is connected to the peripheral circuit 3 through a bus 10.
To exchange data with In particular, in the CPU 2, the multitask OS is running, and the processing greatly changes over time, and accordingly, the power consumption of the CPU 2 also greatly changes. Also, the power consumption of the peripheral circuit 3 greatly changes in accordance with the operation of the CPU 2. Since the power consumption other than the CPU 2 and the peripheral circuit 3 is not so large, the CPU 2
The change in the task causes a great change in the power consumption of the entire portable information terminal. The A / D converter 6 receives the voltage measurement request 17 from the CPU 2 through the bus 10,
The voltage of the lithium ion battery 1 supplied through a voltage measurement line 12 branched from the voltage supply line 11 is A / D converted, and the measurement result is transmitted to the CPU 2 through a measurement result line 13.

In such a conventional portable information terminal, the method of measuring the remaining battery power is as follows.
After all the tasks in which S is running are stopped, the battery remaining amount monitoring task 21 is started, whereby the power consumption of the CPU 2 is made constant and the load on the lithium ion battery 1 is made constant. Next, the battery remaining amount monitoring task 21 outputs a voltage measurement request 17 to the A / D converter 6 via the bus 10, and the A / D converter 6
In response, the D converter 6 measures the voltage of the lithium ion battery 1 through a voltage measurement line 12 branched from the power supply line 11 and outputs the measurement result on a measurement result line 13. The battery remaining amount monitoring task 21 operating on the CPU 2 includes:
The measurement result on the measurement result line 13 is input, and the remaining amount of the lithium ion battery 1 is estimated by comparing with the sample data measured in advance. After estimating the remaining amount of the lithium ion battery 1, the multitask OS on the CPU 2 terminates the remaining battery amount monitoring task 21 and then runs all the tasks stopped for the remaining battery amount measurement again.

[0008]

A problem with the above-mentioned prior art is that a multitasking OS is required to measure the remaining battery level while operating the multitasking OS on a portable information terminal.
Needs to be provided with a mode in which only the remaining battery level monitoring task for stabilizing the power consumption of the CPU is operated. The reason is that when a multitasking OS is run on a portable information terminal, the amount of tasks changes with time.
This is because it is difficult to stabilize the power consumption of the PU, so that the load of the lithium ion battery as the operation power source is not constant, and it is difficult to estimate the remaining battery level.

An object of the present invention is to provide a multitasking OS which is mounted on a portable information terminal without a special mode necessary only for operating a battery remaining amount monitoring task.
An object of the present invention is to provide a battery level monitoring method for a portable information terminal, which can easily mount S on a portable information terminal.

[0010]

SUMMARY OF THE INVENTION A portable information terminal battery level monitoring system according to the present invention uses a battery as a power source and uses a CPU capable of holding a bus. Bus hold request issuing means for issuing a bus hold request, and a voltage for outputting a voltage measurement trigger after a predetermined period of time has elapsed after the bus hold request issued by the bus hold request issuing means until the power consumption of the CPU becomes constant. Measurement trigger means, voltage measurement means for measuring the voltage of the battery in response to a voltage measurement trigger from the voltage measurement trigger means, and battery remaining quantity estimating means for estimating the remaining battery capacity from the measurement result by the voltage measurement means And characterized in that:

[0011] In the portable information terminal of the present invention, the battery remaining amount monitoring method is a method in which a battery is used as a power source and a bus can be held.
In the portable information terminal using U, a battery level monitoring task which is started up at regular time intervals, issues a voltage measurement request, inputs a measurement result and estimates the battery level, and A bus hold control circuit for issuing a bus hold request to the CPU based on the voltage measurement request and receiving a bus hold request acknowledgment from the CPU;
After receiving the bus hold request acknowledgment from U,
A voltage measurement start timer that outputs a voltage measurement trigger after a predetermined time or more elapses until the power consumption of U becomes constant, and receives a voltage measurement trigger from the voltage measurement start timer to measure the voltage of the battery, A / to output the measurement result
And a D converter.

In a portable information terminal battery monitoring method according to the present invention, in a portable information terminal using a CPU capable of holding a bus based on a DMA request by using a battery as a power source, a DMA request is issued to the CPU. And a DMA circuit that receives a DMA request acknowledgement from the CPU, and after a predetermined time equal to or longer than the time until the power consumption of the CPU becomes constant after receiving the DMA request acknowledgement from the CPU. A voltage measurement start timer that outputs a voltage measurement trigger, an A / D converter that measures the voltage of the battery in response to a voltage measurement trigger from the voltage measurement start timer, and outputs a measurement result; And a battery remaining amount monitoring task for inputting the measurement result and estimating a battery remaining amount.

[0013]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a main part circuit block diagram showing a configuration of a battery remaining amount monitoring system of a portable information terminal according to a first embodiment of the present invention. The battery level monitoring method for a portable information terminal according to the present embodiment includes a lithium ion battery 1 as an operating power supply, a CPU 2 as a central processing unit, and a peripheral circuit 3 for inputting and outputting communication, key input, display, and the like. A bus hold control circuit 4 for issuing a bus hold request, a voltage measurement start timer 5 for generating a battery voltage measurement timing,
An A / D converter 6 for measuring the battery voltage and a main memory 7 in which a multitask OS (not shown), a battery remaining amount monitoring task 21 (operating on the CPU 2 in the figure) and the like are stored. Its main part is configured.

The lithium-ion battery 1 is a coke-based lithium-ion battery, and has a discharge characteristic in which a discharge voltage gradually decreases according to a discharge time, as illustrated in FIG. The lithium-ion battery 1 is an operation power supply of the portable information terminal, and supplies power to each block constituting the portable information terminal other than itself through the power supply line 11.

The CPU 2 controls the peripheral circuit 3 via the bus 10.
To perform processing as a portable information terminal on a multitask OS by multitasking. The CPU 2 is loaded with a program (a battery remaining amount monitoring task 21) for starting a process of measuring the remaining battery amount at intervals of about once every few minutes in the multitasking process.

When the bus hold control circuit 4 receives the voltage measurement request 17 from the CPU 2 via the bus 10, the bus hold request line 15 and the bus hold request
A bus hold request and a bus hold request acknowledgment are transmitted and received through the
To hold the bus 10. Further, when notified of the end of the voltage measurement from the voltage measurement start timer 5 via the measurement end line 18, the bus hold control circuit 4 sends the bus hold request line 15 and the bus hold request The CPU 2 receives the release and the bus hold request acknowledgment release, and causes the CPU 2 to release the hold of the bus 10.

When the voltage measurement start timer 5 receives the bus hold request and the bus hold request acknowledgment via the bus hold request line 15 and the bus hold request acknowledgment line 16, the bus 10 is held, and the operation of the CPU 2 is stopped. Is measured for a predetermined time or more until the current consumption becomes constant, and after the predetermined time, the voltage measurement trigger line 1 is measured.
A trigger of voltage measurement is applied to the A / D converter 6 via the terminal 4. Further, after a fixed time equal to or longer than the time until the voltage measurement in the A / D converter 6 ends, the voltage measurement start timer 5
Informs the bus hold control circuit 4 of the end of measurement via the measurement end line 18.

The A / D converter 6 inputs a voltage of the lithium ion battery 1 through a voltage measurement line 12 branched from a power supply line 11 to perform A / D conversion.
The value is held in response to the trigger of the voltage measurement from No. 4 and the measurement result is output on the measurement result line 13.

Next, the operation of the battery level monitoring system of the portable information terminal according to the first embodiment configured as described above will be described.

Normally, the CPU 2 performs multitask processing as a portable information terminal with the peripheral circuit 3 through the bus 10. Further, the CPU 2 activates the battery remaining amount monitoring task 21 for the multitask OS to measure the battery remaining amount at intervals of several minutes, and issues a voltage measurement request 17 to the bus hold control circuit 4.

When receiving the voltage measurement request 17 via the bus 10, the bus hold control circuit 4 issues a bus hold request to the CPU 2 and the voltage measurement start timer 5 via the bus hold request line 15.

When receiving the bus hold request, the CPU 2 holds the bus 10 and returns a bus hold request acknowledgment to the bus hold control circuit 4 and the voltage measurement start timer 5 via the bus hold request acknowledgment line 16.

When the CPU 2 holds the bus 10 for a certain period of time, if there is no large-capacity cache memory in the CPU 2, the processing code cannot be fetched. Task stops working. For this reason, the current consumption of the CPU 2 can be made constant, and when the current consumption of the CPU 2 is made constant, the current consumption of the entire portable information terminal also becomes constant, so that the load on the lithium ion battery 1 serving as the operation power source becomes a constant value. .

When the voltage measurement start timer 5 receives the bus hold request from the bus hold control circuit 4 and the acknowledgment of the bus hold request from the CPU 2, the voltage measurement start timer 5 waits for a predetermined time longer than the time when the operation of the CPU 2 is stopped after the bus 10 is held. (For example, several tens of clocks), and the CPU 2 stops the A / D converter 6 through the voltage measurement trigger line 14 to give a timing at which a certain load is applied to the lithium ion battery 1. Further, after a certain period of time equal to or longer than the end of the voltage measurement in the A / D converter 6, the voltage measurement start timer 5 causes the bus hold circuit 4 to end the measurement for releasing the hold of the bus 10 via the measurement end line 18. Notify.

When the A / D converter 6 is triggered by the voltage measurement via the voltage measurement trigger line 14, the A / D converter 6 A / D converts the voltage of the lithium ion battery 1 via the voltage measurement line 12 branched from the power supply line 11. The voltage value is held as a measurement result and output to the measurement result line 13.

The bus hold control circuit 4 controls the measurement end line 1
When the end of the measurement is notified through 8, a bus hold request release is issued to the CPU 2 and the voltage measurement start timer 5 via the bus hold request line 15.

When receiving the bus hold request release, the CPU 2 releases the hold of the bus 10 and returns the bus hold request release to the bus hold control circuit 4 and the voltage measurement start timer 5 via the bus hold request confirmation line 16. .

When the CPU 2 releases the hold of the bus 10, the processing code can be fetched from the main memory 7, and all the stopped tasks including the battery voltage monitoring task 21 resume the operation.

Battery voltage monitoring task 21 resumed operation
Inputs the measurement result of the A / D converter 6 through the measurement result line 13 and compares the measurement result with sample data which has been measured in advance to obtain the lithium ion battery 1.
Estimate the remaining battery power. For example, as shown in FIG.
When a coke-based lithium-ion battery 1 that can be used for 5 hours at a minimum discharge current (270 mA) is used as an operating power source, if the measurement result is a, the discharge time is 2 hours, so the remaining battery charge is (5- 2) Estimate that ÷ 5 × 100 = 60%. If the measurement result is b, the discharge time is 3
Time, the remaining battery power is (5-3) ÷ 5 × 100 =
Estimate to be 40%. Furthermore, if the measurement result is c, the discharge time is 5 hours, so the remaining battery charge is (5-5)
It is estimated that ÷ 5 × 100 = 0%.

As described above, in the battery remaining amount monitoring method of the portable information terminal according to the first embodiment, even if a plurality of tasks are running on the multitask OS in the CPU 2, the lithium ion battery Since the load of the battery 1 can be kept constant, the remaining amount of the lithium ion battery 1 can be easily monitored.

FIG. 2 is a main circuit block diagram showing a configuration of a battery remaining amount monitoring method of a portable information terminal according to a second embodiment of the present invention. In the present embodiment, the portable information terminal itself periodically holds a DMA (Direct Mem) such that it holds the bus 10 of the CPU 2 at fixed time intervals.
3 shows an example in which a circuit for performing an access operation, for example, a video circuit 8 is provided. In this case, the bus hold control circuit 4 in FIG. 1 may be used in place of the video circuit 8, and the bus hold request line 15 and the bus hold request acknowledge line 16 may be replaced with the DMA request line 19 and the DMA request acknowledge line 20, respectively. . In addition,
The other circuits and the like are configured in the same manner as the corresponding circuits and the like in the battery level monitoring method of the portable information terminal according to the first embodiment shown in FIG. 1, and thus detailed description thereof will be omitted.

According to the battery level monitoring method for the portable information terminal according to the second embodiment, the video circuit 8 periodically performs DMA, so that the CPU 2 measures the voltage every few minutes. A / D without issuing request 17
The result of the measurement in the converter 6 is
Since it is updated every time the MA is performed, the battery remaining amount monitoring task 21 only needs to input the measurement result through the measurement result line 13 every few minutes, and the
, It is possible to estimate the remaining battery level. Therefore, compared to the first embodiment,
There is an advantage that the remaining battery level can be monitored with simpler hardware and software. It is needless to say that the circuit that periodically performs the DMA is not limited to the video circuit 8.

In each of the above embodiments, the battery used as the operating power source is the coke-based lithium-ion battery 1. However, the battery is not limited to this.
The present invention can be similarly applied to any battery as long as the battery has a characteristic such that the discharge voltage gradually decreases with respect to the discharge time as exemplified in (1).

In each of the above embodiments, the OS mounted on the CPU 2 is described as a multitask OS, but the present invention can be applied to a portable information terminal using a single task OS in the same manner. .

[0036]

As described above, according to the present invention,
A bus hold request issuing unit for issuing a bus hold request to the CPU at the time of measuring the remaining battery level, and a voltage after a predetermined period of time has elapsed after the bus hold request issued by the bus hold request issuing unit until the power consumption of the CPU becomes constant. Voltage measurement trigger means for outputting a measurement trigger, voltage measurement means for receiving a voltage measurement trigger from the voltage measurement trigger means to measure the voltage of the battery, and battery remaining for estimating the remaining battery level from the measurement result by the voltage measurement means. By providing the amount estimating means, the multitask OS mounted on the portable information terminal can be easily mounted on the portable information terminal without adding a special mode necessary only for measuring the remaining battery level. There is an effect that can be. As a result, the implementation of the OS is simplified, so that more types of OS can be loaded on the portable information terminal.

[Brief description of the drawings]

FIG. 1 is a main part circuit block diagram showing a configuration of a battery remaining amount monitoring method of a portable information terminal according to a first embodiment of the present invention.

FIG. 2 is a main part circuit block diagram showing a configuration of a battery remaining amount monitoring method of a portable information terminal according to a second embodiment of the present invention.

FIG. 3 is a graph showing discharge characteristics of a coke-based lithium ion battery.

FIG. 4 is a main part circuit block diagram showing an example of a conventional battery level monitoring method for a portable information terminal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lithium ion battery 2 CPU 3 Peripheral circuit 4 Bus hold control circuit 5 Voltage measurement start timer 6 A / D converter 7 Main memory 8 Video circuit 10 Bus 11 Power supply line 12 Voltage measurement line 13 Measurement result line 14 Voltage measurement trigger line 15 Bus hold request line 16 Bus hold request acknowledgment line 17 Voltage measurement request 18 Measurement end line 19 DMA request line 20 DMA request acknowledgment line 21 Battery level monitoring task

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G06F 1/26-1/32 H01M 10/00-10/34 H02J ^7/ 00-7/12

Claims (4)

(57) [Claims] A portable information terminal using a battery as a power supply and a CPU capable of holding a bus, a bus hold request issuing means for issuing a bus hold request to the CPU when measuring the remaining battery charge, Voltage measurement trigger means for outputting a voltage measurement trigger after a predetermined period of time elapses from the bus hold request by the issuing means until the power consumption of the CPU becomes constant, and receiving a voltage measurement trigger from the voltage measurement trigger means A battery level monitoring method for a portable information terminal, comprising: voltage measuring means for measuring the voltage of the battery; and battery level estimating means for estimating the remaining level of the battery from the measurement result by the voltage measuring means. 2. A portable information terminal using a battery as a power supply and using a CPU capable of holding a bus is activated at regular time intervals, issues a voltage measurement request, inputs a measurement result, and estimates the remaining battery level. A battery level monitoring task, a bus hold control circuit that issues a bus hold request to the CPU based on a voltage measurement request from the battery level monitoring task, and receives a bus hold request acknowledgment from the CPU; A voltage measurement start timer that outputs a voltage measurement trigger after a predetermined period of time elapses from the reception of the bus hold request acknowledgment until the power consumption of the CPU becomes constant, and a voltage measurement trigger from the voltage measurement start timer. And an A / D converter for measuring the voltage of the battery in response to the signal and outputting the measurement result. Method. 3. A portable information terminal that uses a battery as a power supply and uses a CPU capable of holding a bus based on a DMA request. The mobile information terminal periodically issues a DMA request to the CPU, and acknowledges the DMA request from the CPU. A DMA circuit for receiving, and C after receiving a DMA request acknowledge from the CPU.
A voltage measurement start timer that outputs a voltage measurement trigger after a predetermined period of time or more elapses until the power consumption of the PU becomes constant, and receives a voltage measurement trigger from the voltage measurement start timer to measure the voltage of the battery, A portable information terminal comprising: an A / D converter that outputs a measurement result; and a battery remaining amount monitoring task that is started at regular time intervals and inputs the measurement result to estimate a remaining battery amount. Quantity monitoring method. 4. The method according to claim 3, wherein the DMA circuit is a video circuit that periodically performs DMA.