Patent Application
20080004762
The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides an application specific integrated circuit (ASIC) designed for a scan tool.
Memory card reader 110 can be a single type card reader, such as a compact flash card, floppy disc, memory stick, secure digital, flash memory or other types of memory. The memory card reader 110 can be a reader that reads more than one of the aforementioned memory such as a combination memory card reader. Additionally, the card reader 110 can also read any other computer readable medium, such as CD, DVD, UMD, etc.
The connector interface 112 allows the scan tool 100 to connect to an external device, such as an ECU (electronic control unit) of a vehicle, a computing device, an external communication device (such as a modem), a network, etc. through a wired or wireless connection. Interface 112 can also include a USB, FIREWIRE, modem, RS232, RS48J, and other connections to communicate with external devices, such as a hard drive, USB drive, CD player, DVD player, UMD player or other computer readable medium devices.
The power supply module 202 provides power to the ASIC and the rest of the scan tool. The power supply module can be powered by the internal device battery 204 (for example, 4 AA batteries) or from the vehicle battery 206, when the scan tool 100 is connected to the ECU of the vehicle. In one embodiment, the power supply module can include three regulators (not shown) and one regulator controller (not shown). However, as many regulators and regulator controllers can be utilized as required and are not limited to the amount disclosed herein. A 7.5V regulator and 5V charge pump are used to provide voltage swings and input references for the vehicle interface transceivers. The 3.3V supplier is used in tandem with an external pass FET to allow for higher current requirements. For example, the 3.3V can supply the microcontroller, external Flash memory, and the display circuits. A second 3.3 regulator (unswitched) can be powered and is used to provide power to the external battery-backed SRAM. A 5V supply can power the vehicle interface or the CAN (control area network) transceiver (discussed below).
The power supply module also include a low battery detect circuit used to digitally signal the microcontroller that the tool power has reached an unsafe voltage level so that appropriate action can be taken by the microcontroller to signal a shut down is imminent or for the user to plug the scan tool into another battery source, such as the vehicle's battery. Additionally, the power supply module can include the power key 108 that includes a momentary external switch that when pressed for the first time, powers the scan tool on and when pressed a second time will interrupt the microcontroller. The power supply module can provide a digital power-on-reset to hold the processor reset during power up and down cycles.
The keyboard interface 210 supports a keyboard connector 208, which is connected to the user interface or keyboard 106. The keyboard may have a matrix of 4×4, for example, or any configuration desired including an alpha-numeric keyboard. The keyboard 106 can include function keys, arrow keys or any other type of keys that can manipulate the scan tool 100 in order to operate the software. Other input device, such as a stylus, touch-screen, mouse or other pointing devices are also contemplated in this embodiment.
An oscillator 212 can include a clock module and provide all the necessary clocks for the internal digital circuits, including the input clock for the microcontroller 214 (discussed below). Additionally, the oscillator 212 can provide the clock for the CAN bit processing (discussed below). In one embodiment, the oscillator clock runs at 16 MHz and can be used to provide the CAN bit processing timing to achieve the 1 Mbit maximum data rate. Other clock speed and data rates are also contemplated within this disclosure.
The microcontroller 214 can be any controller or microprocessor that is capable of computing and controlling the scan tool and its function. For examples, the microcontroller can be a R80515 RISC (Reduced-Instruction Set), 8-bit microcontroller clocked at 8 Mhz. The microcontroller can be in communication with an SRAM (static random access memory) and a boot ROM (read only memory) that contains the program that boots the ASIC upon being powered. The memory interface 230 communicates with the memory card reader 110, which can store additional memory, such as a battery backed SRAM 228 and/or a flash memory 226, for use by the microcontroller.
The microcontroller 214 can include the standard set of 8051 compatible peripherals plus a second data pointer to speed up memory move instructions. The internal and external peripherals for the R80515 reside in the SFR (special function registers) memory space and can be accessed using 8051 direct memory instructions. SFRs are bit, byte, or word-sized registers that are used to control timers, counters, serial I/O, port I/O, and peripherals.
The ASIC also includes an on-chip instrumentation interface (OCI) 220 that communicates with the microcontroller 214. The OCI includes a start/stop control, unlimited number of software breakpoints, assembly level single-step, and hardware breakpoints. Each hardware breakpoint includes one address/data value and one memory space modifier.
The vehicle data link controller 216 and vehicle digital interface logic 218 interact with the connector interface 112, which connects to the vehicle's ECU in order for the scan tool 100 to interact with the vehicle. The CAN (controlled area network) transceiver 222 also communicates with vehicle data link controller 216, the connector interface 112, and the vehicle digital interface logic 218. The vehicle data link controller 216 possess all the necessary encoder and decoder and all transmitters and receivers for the various communication protocols. The scan tool 100 communicates with the ECU through various communication protocols, such as CAN (ISO 11898), GM 80/160 Baud, GM 8192 ALDL, Chrysler SCI, KOEO (Ford), KOER (Ford), DCL (Ford), ISO 9141, J1850 VPW, J1850 PWM, and J1708. Aperson skilledinthe art will recognize that the ASIC described herein is capable of communicating in other any communication protocol with little or no modifications.
Data can be written into the TxRAM 310 by the microcontroller to form a frame for transmission. The TxRAM, for example, can be 16 bytes deep and will be written and read sequentially. If a frame loses arbitration during transmission, the address to the RAM is automatically reset allowing for two additional transmission retries without the microcontroller having to reload the frame into RAM again. Once transmission is enabled, the data in the TxRAM is converted from parallel to serial, encoded and provided to the vehicle interface for transmission. As bits are received from the vehicle interface, they are decoded, converted from serial to parallel and loaded into the RxFIFO 312, where they can be read by the microcontroller. The RxFIFO 312, for example, can be 32 bytes deep and allows the reception of multiple frames. This allows concurrency between the reception of a second frame while the microcontroller is still processing the first. The serial transmit path can select multiple digital outputs to be asserted allowing programmability for the vehicle interface drivers. The receive path can be selected from one of multiple sources allowing different receivers to be used to meet the various vehicle interface standards. The selected receive path is first routed to the “no-glitch” filter on the vehicle interface logic 328 to eliminate any small glitches that may occur during frame reception.
By using a customable ASIC, the scan tool can be manufactured to the specification required by using fewer number of vendors. Additional communication protocols can be readily added or removed due to common pathways that are used to communicate between the vehicle and the ECU. Other components can also be readily added or removed from the ASIC due to a dynamic power supply module that can provide power at different voltages.
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
