The AMT-based MC9S08DZ60 ECU handle design

    (Hefei University of Electrical Engineering and Automation, Hefei 230009)

 

    Abstract: The shift lever in the AMT car ECU hardware and software design, the use of MC9S08D260 MCU CAN module with the vehicle ECU AMT handle data communication between other systems. The handle ECU has a simple structure, low cost, powerful features.

 

    Keywords: Handle ECU; AMT; MC9S08D260; CAN bus

 

    CLC: TN92 Document code: A Article ID :1674 -7720 (2011) 07-0104-03

 

    Digital circuits can be implemented quickly and easily handle gear shift signal transmission, but the communication between the control unit reliability, timeliness, safety and other aspects of CAN bus technology is not good. In this design, the handle to the ECU via CAN bus pass a driver's intention AMT_ECU, AMT's ECU ECU under the handle packets of information that are passed for controlling transmission shift action. Simultaneously. AMT-ECU via CAN bus can also be the current state of the transmission gear f such a status and fault status sent to the shift lever circuits. By occupants shift lever to select the current expectations of the gear, handle ECU Hall sensor according to the received transmission lever position information, perform the input signal processing, and the gear after send information through the CAN bus AMT-ECU, passing the driver's driving intention. ECU ECU under the AMT handle the information conveyed by the control packet transmission shift movements. There microcontroller as due to their own processing units can be used CAN / LIN bus communication ways and TCU. Basically do not take the TCU interface resources. When the signal acquisition circuit m current problems, the microcontroller can be white line diagnostics, and even simple faults can replace TCU processing [l1. The design of the control circuit structure is simple, low cost, powerful.

 

A hardware design

 

    The design of the hardware circuit is MC9S08D260 microcontroller as the core, including chip peripheral circuits, power conversion circuits, switch the input m processing circuit and CAN communication circuit.

 

1.1 smallest single-chip system

 

    As a small but functional handle ECU whole system, so the use of Motorola's 8-bit microcontroller MC9S08D260. The microcontroller small size, low cost, powerful, full of resources, with high performance and low cost, suitable for car handle shifting functional requirements as well as automotive operating environment. Its main resources include: a CAN module, a serial peripheral interface SPI module, two serial communication interface SCI module, up to 24 channels of 12 bit A / D converter module, a basic clock module, 60 KB of on-chip Flash, 4 KB of on-chip RAM, 2 KB of E2PROM, watchdog timer (COP Watc, h - dog), in addition to the I2C bus module and a plurality of timers, counters, and so on. The mining weeks PLL PLL controller, capable of generating up to 40 MHz bus frequency. Its unique on-chip emulation / deep test module (BDC) is greatly simplifies the design, ensuring MC9S08D260 in this design application status [31. Its peripheral circuit shown in Figure l.

 

1.2 Power Module

 

    The module uses 7805 (UI) chip converts +12 V +5 V, MIC29510-3.3 (U2) chip +5 V +3.3 V. Conversion To meet the power of the whole system, including single-chip power supply. Its circuit shown in Figure 2.

 

1.3 digital processing module

 

    In order to make the switch input signal is more reliable. Each binary inputs go through the pull-up, current limiting and other processing into the microcontroller. When the handle to the desired gear selection into the Hall sensor within the magnetic grid, the sensor outputs a high level signal +3.3 V: the rest of the magnetic sensor input is not connected to the grid range, the output low-level signals jh is OV. This design uses a Hall sensor input voltage is +12 V.

 

1.4 CAN communication circuit

 

    The design of the vehicle as a node in a distributed control system. Communicate with other on-board controller using CAN network communications. The design of collection system state variables, and command messages via CAN uploaded to the vehicle controller T for, CAN transceiver PHILIPS company PCA82C250 transceiver. The hardware circuit shown in Figure 3.

 

2 Software Design

 

    System software design, including data acquisition and storage, and two CAN communication module. 2.1 CAN communication module MC9S08D260 integrated within the application CAN 2.OA / B protocol of the CAN controller. Contains five advanced receiver register first m, 3 using a local priority transmit register. In the ID recognition provides 64 bit mask register, can be divided into two 32 bit with the full value of the register, or four 16 bit, 8 个 8 bit registers, which makes the news on the bus addressing more flexible and convenient . To meet the low power requirements, this module provides sleep, power-down, and MSCAN Enable 3 God mode f 51.

 

    CAN bus data frame consists of seven different bit fields: start of frame, arbitration field, control field, data field, CRC field, the response field, the frame end. The length of the data field which can be 0, but the module encapsulation frame up no more than 8 bytes. According to the arbitration bits can be divided into standard frame (11 bit identifier) ​​and extended frame (29 bit identifier 1 extended frame format includes four ID register IRDO ~ IRD3.8 data registers DSRO and a data length register DLR of which the first is ID28.IRD3 IRDO bottom is IDO. still exists between the signal flag SRR, IDE and RTRc4i. 2.2 CAN communication protocol

 

    CAN bus communication using caller polling. As the CAN constraints, each child node within the network should not be more than 1 000. Take 10 bit here as the source and destination device ID. Because only 1 ID28. ID27 ~ ID18 defined here as the frame source ID, rather than a frame ID17 ~ ID8 purpose ID. Because communication need to transfer data more than 8 bytes. Here the DSRO transmit multiple frames as the total number of frames of data registers, the DSRI transmit multiple frame data as the current frame register. DSR2 as a frame function registers. DSR3 ~ DSR6 transmit data. DSR7 the checksum register.

 

2.3 Program Design

 

    Initializef) complete single-chip hardware initialization f handle ECU initialization, application initialization chips 1. After power-on initialization, the microcontroller began collecting I / O port gear voltage signal and stored on-chip storage unit. CAN communication with the host interrupt will be done in the form. Figure 5 is a system overall process.

 

    The gear position corresponds to the logic level as shown in Table l.

 

    After testing, CAN bus transmission gear change information shown in Figure 6. The test proved that the handle ECU can be achieved under laboratory conditions, data acquisition and network communications. And achieve shift targets. Using CAN bus technology can not only reduce costs handle ECU, data sharing, but also can improve the performance of AMT. The highest l Mb / s (40m or less so that the transmission speed of 1 ECU handle real-time, high reliability and good condition.