Method of self-diagnosing a mobile telephone set for use in a mobile telephone switching system and mobile telephone set being applied to the method

Abstract: The present invention relates to a self-diagnosing method which shortens the diagnosing time for a ROM which is provided within a mobile telephone set for use in a mobile telephone switching system and mobile telephone set being applied the method. When the power supply is turned ON, a complementary value which complements to set up the sum of data stored within all the addresses of the ROM as a certain specific value, ROMCHK, which is the content of the data stored within a specific address of the ROM, is compared with NVMCHK which is the content of data stored previously within a specific address of a non-volatile memory with the same value as the ROMCHK. If they do not coincide, then the content of the data within the entire area of the ROM is calculated for the diagnosis. In this case, the content stored within the specific address of the ROM is the sum of the data values within the entire area of the ROM, and the content stored within the specific address of the non-volatile memory is the same as this sum value.

Description: The present invention relates to a method of self-diagnosing a mobile telephone set for use in a mobile telephone switching system, and particularly to a method of self-diagnosing a read-only memory (hereinafter referred to as ROM) which is provided with the mobile telephone set, and to a mobile telephone set for employing the method. In mobile telephone sets, various self-diagnoses are carried out when the power supply is turned ON, and the reliability of mobile telephone sets is improved by preventing use unless the mobile telephone sets are determined to be normal as a result of self-diagnoses. The self-diagnoses, include a diagnosis for a ROM provided within the telephone sets, which must be carried out without fail. In this case, the contents of all the addresses of the ROM are read out to carry out operations such as summing up or logic calculus exclusive OR. If each operational result turns out to be a value calculated previously, then a content of the ROM is determined to be normal, while, if not, then it is determined that something abnormal exists within the content of the ROM and the user is informed of that fact. Incidentally, in recent mobile telephone sets, as the program size of the man-machine interface portion has been increased in order to achieve various functions, the capacity of ROM has been correspondingly increased from 512 kbits to 1 Mbit. As a result, there has arisen a problem in that it takes a long time for diagnosis if, each time the power supply is turned ON, the contents of all the addresses of ROM is read out for operation and the result of this operation is compared with a specific value to diagnose the ROM. For example, if a typical eight-bit microprocessor (hereinafter referred to as a CPU) takes about 1 to 2 seconds for the diagnosis, it takes about 1 to 2 seconds until the telephone set becomes operable after the power supply is turned ON, which irritates the user and results in a serious problem to impair the reputation of the mobile telephone switching system. In addition, also for the manufacturer, since the telephone set cannot be tested for about 1 to 2 seconds after the power supply is turned ON, the number of man-hours required for inspection is increased thereby resulting in an increase in manufacturing cost. Features of a method to be described below, are that the self-diagnosing time of a mobile telephone set is shortened, that the mobile telephone set is made available for use within a reduced period of time after the power supply is turned ON, and that the mobile telephone set is made available for inspection promptly after the power supply is turned ON at the inspection stage during manufacture. A particular method to be described below, as an example, includes the steps of comparing the content of the data stored within a specific address of a ROM with that stored within a specific address of a non-volatile memory when the power supply is turned ON, determining whether the ROM is normal or not by comparing whether the contents of the two data coincide with each other, and calculating the data stored within all the addresses of the ROM according to a predetermined calculus in order to compare the result of the calculation with the data stored within the non-volatile memory, when the contents of the two data do not coincide. The content of the data stored within the specific address of the ROM may be the sum of the data stored within all the areas of the ROM, the value complementing the sum as a certain specific value, and being the result of an exclusive logical OR of the data stored within all of the addresses of the ROM, or the sum of the cyclic redundancy codes for each data within all of the addresses of the ROM. There will also be described below, as an example a mobile telephone set employing a method of shortening the self-diagnosing time, and including first memory means having a plurality of memory locations in each of which data are to be stored, second memory means having a specific memory location in which data are to be stored, means for comparing first data stored in one of the plurality of memory locations with second data stored in the specific memory location, calculation means for making a calculation on all data stored in the plurality of memory locations when the first and second data do not coincide with each other, to produce a calculation result, means for comparing the calculation result with a predeter-mined value and means for indicating that the first memory means is abnormal when the calculation result differs from the predetermined value. Further, the calculation means for making a calculation on all data stored in the plurality of memory locations may be means for summing all data stored in the plurality of memory locations to produce the sum of all of the data as the calculation result, the first memory means may be a read only memory (ROM) and the second memory means may be a non-volatile memory in the mobile telephone set. The following description and drawings disclose, by means of an example, the invention which is characterised in the appended claims, whose terms determine the extent of the protection conferred hereby. In the drawings:- Fig. 1 is a flowchart of a specific embodiment of a self-diagnosing method for a mobile telephone set, and Fig. 2 is a block schematic diagram of a mobile telephone set to which the self-diagnosing method illustrated in Fig. 1 is applied. Referring to the drawings, Fig. 2 is a block schematic circuit diagram of the essential portion of a mobile telephone set to which a self-diagnosing method illustrated in Fig. 1 is applied. This mobile telephone set includes a CPU 1, a ROM 2 and a non-volatile memory 3. Any arbitrary content of the ROM 2 can be written into any arbitrary address within the non-volatile memory 3. The CPU 1 determines whether the content of the data stored within a specific address of the ROM 2 and that of the non-volatile memory 3 coincide by comparing them. Based on this circuit arrangement, the diagnosing method employed will now be described with reference to Fig. 1. At first, in step S1, the mobile telephone set is initialized. Next, in step S2, CPU 1 compares ROMCHK, which is data stored within a specific address of ROM 2, with NVMCHK which is data stored within a specific address of the non-volatile memory 3. The value of ROMCHK is the complementary data provided to set up the sum of the values of the data of all the addresses of ROM 2 as a certain specific value, for example, 0000H, which is assigned at the stage of factory inspection, while NVMCHK is the same value as that described above, which is stored within non-volatile memory 3. In this case, the content of NVCHK is previously written within the specific address of non-volatile memory 3. If both contents coincide, then ROM 2 is determined to be normal, after which the self-diagnosis proceeds to the next self-diagnosing operation step S7. If they do not coincide, the operation proceeds to step S3 deciding that some change has been added to the content of ROM 2. In step S3, the data values of all the addresses of ROM 2 are read out, and their sum is calculated as a checking sum (hereinafter referred to as CSUM). Step S4 is for determining whether the value of CSUM is equal to the value calculated and stored in another address of ROM 2 previously, for example, 00A0H and, if it is a value other than 00A0H, then it is determined that something abnormal exists in the content of ROM 2, and indicates to the user that ROM 2 is abnormal in step S5. On the other hand, if the value of CSUM is 00A0H, then it is determined that the content of ROM 2 is normal, and after revising the value of ROMCHK of ROM 2 and the value of NVMCHK of the non-volatile memory 3 in step 6, proceeds to carry out next self-diagnosing operation step 7. Incidentally, although in this embodiment, a complementary value, which complements the setting-up of the sum of the data of all of the areas of the ROM as a predetermined value, is compared in order to determine the validity of the ROM, the value may be that sum per se, the exclusive logical OR of the data within all of the addresses of the ROM 2, or the sum of the cyclic redundancy codes of the data within all of the addresses of the ROM 2. While certain representative embodiments have been described for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the protection sought by the appended claims.

Claims: A method of self-diagnosing a mobile telephone set for use in a mobile telephone switching system, the telephone set having a ROM, read only memory, (2), a non-volatile memory (3) and a microprocessor (1) and incorporating data, the content of which is the result of a calculation based on all of the data stored within specific locations in the ROM (2) and in the non-volatile memory (3) and made according to a predetermined formula, the method including the steps of comparing the content of the data stored in a specific location of the ROM (2) with the content of the data stored in a specific location of the non-volatile memory when the power supply is turned ON, and, when the content of the data stored in the specific locations of the ROM (2) and the non-volatile memory (3) do not coincide, calculating the sum of all of the data stored in the ROM (2) and, when the calculated result differs from the content of the data stored in the non-volatile memory (3), indicating the abnormality of the ROM (2). A method of self-diagnosing a mobile telephone set as claimed in Claim 1 wherein, when the content of the data stored within the specific location of the ROM (2), and the content of the data stored within the specific location of the non-volatile memory are the same, it is determined that the content of the ROM(2) is normal and that the next step in the self-diagnosing operation may be carried out. A method of self-diagnosing a mobile telephone set as claimed in Claim 1 which includes the steps of determining whether the content of the data stored within the specific location of the ROM (2) is the exclusive OR of the data stored within all of the address of the ROM (2), and whether the content of the data stored within the specific location of the non-volatile memory is the same as the exclusive OR. A method of self-diagnosing a mobile telephone set as claimed in Claim 1 wherein the content of the data stored in a specific location of the ROM (2) is the sum of the cyclic redundancy codes of the data stored in all of the locations of the ROM (2), which includes the step of determining whether the content of the data stored within a specific location of the non-volatile memory (3) has the same value as the sum of the cyclic redundancy codes of the data stored in all of the locations of the ROM (2). A method of self-diagnosing a mobile telephone set as claimed in Claim 1 wherein the content of the data stored in a specific location of the ROM (2) is a complementary value which complements that of the sum of the data stored in all of the locations of the ROM (2), and the content of the data stored in the specific location of the non-volatile memory (3) is the same as that of the complementary value. An apparatus for use in the self-diagnoses of a telephone set including a ROM, read-only memory, (2) having a plurality of memory locations in each of which data are to be stored, a non-volatile memory (3) having a specific memory location in which data are to be stored, a comparator (CPU1) for comparing first data stored in one of the plurality of memory locations in the ROM (2) with second data store in the specific memory locations of the non-volatile memory (3), a calculator (CPU1) for calculating the sum of the data stored in the plurality of memory locations of the ROM (2), when the first and second data do not coincide with each other, to produce a calculated result, a comparator (CPU1) for comparing the calculated result with a predetermined value, and an indicator for indicating that the ROM (2) is abnormal when the calculated result differs from the predetermined value. An apparatus as claimed in Claim 6, wherein the calculator (CPU1) includes means for summing all of the data stored in the plurality of memory locations in the ROM (2) to produce the calculated result.

Inventors: KOMODA MOTOYOSHI, KOMODA, MOTOYOSHI, KOMODA, MOTOYOSHI, C/O NEC CORPORATION
Applicants: NIPPON ELECTRIC CO, NEC CORPORATION
Application year: 1992
Main classification: G06F11
IPC codes: G11C29, H04B7, G06F11, G11C16, G06F12, G11C17, H04Q7