Electronic control apparatus and memory apparatus for electronic control apparatus

• US 20040186866A1
• Filed: 01/27/2004
• Published: 09/23/2004
• Est. Priority Date: 01/27/2003
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Nishimura, Tadaharu, Koto, Kazuhiro
• Granted Patent: US 7,558,811 B2
• Time in Patent Office: Days
• US Class Current: 708/200
• CPC Class Codes: G01F 23/802 Particular electronic circuits for digital processing equipment
• CPC Class Codes: G06F 1/035 Reduction of table size G06F1/0314 takes precedence
• CPC Class Codes: H03M 7/24 Conversion to or from floating-point codes

Abstract

An electronic control apparatus has a memory which stores a map consisting of a set of map points and corresponding set of map values, with the map values representing respective physical quantity values, and at least one of the sets of map points and map values being stored as fixed-point representation data. When a map point is specified, the apparatus obtains a corresponding physical quantity value by converting fixed-point data of the map to floating-point representation, then using a floating-point arithmetic unit to perform an interpolation calculation using the converted data.

Claims

1. An electronic control apparatus which incorporates a floating-point arithmetic function and performs various types of calculation and control operations in accordance with a predetermined computer program, comprising

conversion means for operating on map data that comprise a set of map points and a set of map values respectively corresponding to said map points, to convert at least one of said set of map points and set of map values from fixed-point representation to floating-point representation.

2. An electronic control apparatus according to claim 1, wherein said map points are expressed in floating-point representation in said map data and said map values are expressed in fixed-point representation in said map data, and wherein data expressing said set of map values are of smaller amount that data which express said set of map points.

3. An electronic control apparatus according to claim 1, wherein said map points are expressed in fixed-point representation in said map data and said map values are expressed in floating-point representation in said map data, and wherein data expressing said set of map values are of greater amount than data which express said set of map points.

4. An electronic control apparatus according to claim 1, wherein said map data and said map values are both expressed in fixed-point representation in said map data, and wherein said conversion means performs conversion of both said map points and said map values from fixed-point representation to floating-point representation.

5. An electronic control apparatus according to claim 3 wherein said map values indirectly express respective physical quantity values, and comprising means for providing a LSB conversion value that is expressed in floating-point representation and represents a physical quantity value that has been predetermined as corresponding to a least significant bit of said fixed-point representation data, wherein

said map conversion means generates floating-point data expressing a value of a physical quantity corresponding to an interpolated value of said map values by using said data converted to floating-point representation in conjunction with said LSB conversion value.

6. An electronic control apparatus according to claim 5 wherein said conversion means derives said floating-point representation value of a physical quantity corresponding to an interpolated value of said map values, by successively

operating on said converted floating-point representation data expressing said map values to calculate an interpolated value of said map values, and

using said LSB conversion value to operate on said interpolated value, to obtain said physical quantity value corresponding to said interpolated value.

7. An electronic control apparatus according to claim 6 comprising means for providing data expressing an offset value that has been predetermined as corresponding to said map data, wherein said interpolated value is obtained as a logical value, and wherein conversion means

operates on said logical value with said LSB conversion value, to obtain a provisional value of said physical quantity corresponding to said interpolated value, and

adds said offset value to said provisional value, to obtain said floating-point representation value of a physical quantity corresponding to said interpolated value.

8. An electronic control apparatus according to claim 3, comprising means for providing a LSB conversion value that is expressed in floating-point representation and represents a physical quantity value that has been predetermined as corresponding to a least significant bit of said fixed-point representation data, wherein said conversion means utilizes said LSB conversion value and said map value data converted to floating-point representation to obtain a physical quantity value corresponding to said map point data and expressed in floating-point representation.

9. An electronic control apparatus according to claim 8, comprising means for providing data expressing an offset value that has been predetermined as corresponding to said map data, wherein said conversion means obtains said interpolated value as a logical value, and wherein conversion means

operates on said interpolated value with said LSB conversion value, to obtain a provisional value of said physical quantity corresponding to said interpolated value, and

adds said offset value to said provisional value, to obtain said floating-point representation value of a physical quantity corresponding to said interpolated value.

10. An electronic control apparatus according to claim 1, comprising means for providing ID data which express a type of said fixed-point representation data, wherein said conversion means performs conversion of said floating-point representation data to said fixed-point representation data based on said ID data.

11. An electronic control apparatus according to claim 1, wherein said conversion means executes said conversion by using a program that is written in assembler language.

12. An electronic control apparatus according to claim 1, comprising

means for providing ID (identifier) data which have been predetermined as corresponding to said map data and which indicate whether or not both said map points and said map values of said map data are expressed in floating-point representation, and

means for inhibiting said conversion operation of said conversion means when said ID data indicate that both said map points and said map values are expressed in floating-point representation.

13. A memory apparatus for an electronic control apparatus, said electronic control apparatus executing various types of calculation and control processing in accordance with a predetermined program and having a floating-point arithmetic function, and said memory apparatus having stored therein map data which are used in floating-point calculations,

wherein said map data include a set of map points and a set of map values that respectively correspond to said map points, with at least one of said set of map points and said set of map values being expressed by fixed-point representation data, and wherein said memory apparatus has stored therein, in conjunction with said map data, a LSB conversion value that is expressed in floating-point representation and represents a physical quantity value that has been predetermined as corresponding to a least significant bit of said fixed-point representation data.

14. A memory apparatus for an electronic control apparatus according to claim 13 wherein said memory apparatus has stored therein, in conjunction with said map data, an offset value that is a difference between a physical quantity value and a value that has been generated by converting said fixed-point representation data to floating-point representation data and using said LSB conversion value to operate on a result of an interpolation calculation performed on said converted floating-point representation data.

15. A memory apparatus for an electronic control apparatus according to claim 13, wherein said memory apparatus has stored therein, in conjunction with said map data, ID (identifier) data indicative of a type of said fixed-point representation data.

16. A memory apparatus for an electronic control apparatus according to claim 13, wherein said memory apparatus has stored therein said map data with both said map points and said map values being expressed by floating-point representation data and further has stored therein, in conjunction with said map data, ID (identifier) data indicative of the condition that said map points and map values are both expressed in floating-point representation data.