A quantum leap in microcontroller measurement technology

Innovative ECU measurement concept - maximizes measurement data rate with minimal impact on CPU runtime

As the complexity of ECUs increases, the amount of ECU data is increasing, and the number of measurement and calibration parameters is increasing. The limitations of the measurement, calibration and Flash flashing solutions previously used in data bandwidth have become increasingly obvious. It is against this background that Robet Bosch began to seek more powerful and future-competitive new measurement solutions to meet the needs of the development of the next generation of ECUs, especially the development of a new generation of long-range radar sensors. The long-range

radar sensor LRR3 (Long-Range Radar) developed by Bosch can operate at a frequency of up to 77 GHz, which provides signal input for many safety systems and driver assistance systems in the car, including various versions of the Predictive Safety System (PPS) and Adaptive Cruise Control (ACC). These smallest radar sensors in the automotive electronics industry have been used in automobile production since the beginning of 2009, and have attracted much attention for their advantages of a long-range acquisition range of up to 250 meters and a wide aperture angle of up to 45°. At the same time, its price advantage makes it have a very wide range of applications covering luxury cars, mid-range cars and commercial vehicles. However, Bosch engineers encountered trouble in the measurement and calibration process of this research and development process. In addition to data measurement and recording, calibration and Flash writing all need more efficient solutions, requiring low latency and extremely high data transfer rate characteristics.

From a technical perspective, modularization of the measurement system and the use of standardized PC interfaces are necessary. The development of product ECU prototypes can easily transition from research and development to later stage production. In order to obtain a large number of measurement signals (up to 100,000) and ensure the accuracy of the data, the data rate must reach at least 4 MB/s, while ensuring that the impact on the processor runtime is as small as possible.

Existing solutions: low data rate, high CPU load

When using standardized measurement and calibration protocols CCP or XCP-on-CAN, FlexRay, JTAG or SPI solutions, the protocol driver integrated in the ECU is responsible for cyclically reading, copying and uploading the measurement and calibration signal values. Due to the large amount of measurement data, the memory resources required by the driver will also be relatively large, while the RAM resources of the ECU are very limited. In addition, the bus load will increase, which will have a negative impact on the ECU software. The current data measurement solutions can cover an effective rate range from 50 KB/s based on the CAN bus to a maximum of 400 KB/s based on FlexRay, JTAG and SPI.

High-performance debugging interfaces on microprocessors offer new possible solutions

Bosch decided to work with Vector's technical experts to design a completely new measurement and calibration system. The measurement interface will use the debugging data trace interface that is now increasingly available on mid-range microprocessors. Taking the standard Nexus Class 3 interface as an example, it can transmit information about internal changes in the ECU to the outside world with minimal processor load.

The basic principle of this method is to obtain data from the ECU via the debugging interface and then transmit the data to an external measurement adapter via a specific high-speed cable. The data transmission follows a specific serial communication protocol, while the external measurement adapter can transmit the actual measurement data to an application on a PC independent of the ECU via the standardized XCP-on-Ethernet protocol.

In this project, the ECU interface is connected to a connection piece (POD), which is very compact and easy to install on the ECU. The POD contains all the electronic components required to obtain and transmit the measurement data. In order to ensure normal operation, the POD is fully compatible with the electromechanical working environment of all current ECUs. For example, the POD can be installed in a strategic position in the engine compartment to work, which is also an important requirement of Bosch's R&D project. [page]

Measurement adapter with mirror memory

A 5-meter high-speed serial link (HSSL) cable connects the POD to the VX1110 base module (measurement adapter) in the Vector VX1000 system. The module consists of a FIFO buffer, DPRAM and the XCP driver stored in the RAM. When the host computer has write access to the parameters in the two ECU memory areas defined in advance, the parameters are uploaded to the FIFO buffer in the base module via the HSSL connector and the debug interface. The parameter values ​​are then modified and written to the DPRAM. Logically, the DPRAM always mirrors the current values ​​in the ECU memory area, since the data is identical to the data stored in the ECU. An important feature of this approach is that all measurement processes take place via this mirror memory. To initialize the measurement data, it is only necessary to have the ECU write the event sequence number to the memory address where the measurement data is located. At this point, the FIFO is disconnected from the DPRAM, "freezing" the memory map at the trigger time. This ensures that the data remains unchanged during the measurement period and the XCP driver can process the data according to the protocol.

The XCP-on- Ethernet measurement and calibration protocol is used between the VX1100 and the measurement and calibration tools on the PC, with a transmission rate of up to 5 MB/s. The stable, high-temperature resistant HSSL cable ensures error-free data transmission in the engine compartment, and even if errors occur in the data transmission, the retransmission mechanism will quickly provide a copy of the data packet.

The performance of the system is very valuable. The most impressive thing about the VX1000 measurement system is that it can measure data at a rate of up to 5 MB/s, calibrate at a rate of about 1 MB/s, and handle 100,000 Bosch application parameters with ease. The accuracy of the timestamp is up to 1 microsecond, and the cycle time of the Bypass can be as low as 300 microseconds.

From lab simulation to rapid prototyping

These features make the system ideal for two main applications at Bosch. The first application is bit-accurate vision simulation in the lab, simulating real car driving vision. The second application is bypass, which is used to run and test new functions of ECU extensions. The

above measurement system fully meets all requirements of LRR development and is also being used in other projects of Bosch. Compared with traditional measurement methods, the use of VX1000 solution can improve the measurement performance by 10-100 times. The CPU load of data measurement can be reduced to less than 1%, which is much less than traditional measurement methods. The modular structure of the VX1000 system ensures its reusability in other projects and can even be applied to different microcontrollers, thus effectively saving costs.

The best solution for systems with high data measurement rate requirements

The VX1000 system, as Vector's high-performance measurement and calibration tool, can complete Vector's product line. Because it can achieve unprecedented high data measurement rates, it can meet all the needs of the Bosch project. More importantly, it is precisely because of the good cooperation between the two companies that the comprehensive measurement, calibration and diagnosis tool CANape has played a vital role in the successful completion of the project. CANape is mainly used for calibration work to optimize ECU parameters. In the development and calibration process of driver assistance systems such as ACC, CANape's advanced multimedia options can provide more professional technical support. In addition, it can also display the targets detected by the system in the image window of CANape in video mode, thereby ensuring the reliability of target recognition algorithm verification.

Other applications and prospects

The standard XCP-on-Ethernet protocol can be applied to the VX1000 series products and can also be used for other measurement and calibration tools. In the measurement and calibration tasks of the engine compartment, VX1000 may not be used directly. The harsh working conditions and compact installation space require adaptive modifications to the connection between VX1000 and ECU. In this regard, according to different project requirements, Vector can provide personalized solutions according to the specific needs of customers. Currently, in addition to supporting the Freescale PowerPC processor series, VX1000 also supports the TMS570 series processors produced by TI and the Infineon TriCore series processors with DAP interface widely used in EMS. The solution using the DAP interface is connected to the ECU through a pluggable mini-PC-board. Its measurement and calibration rate can reach 50 microseconds, which is suitable for occasions such as the ECU development of hybrid vehicles.

Given that the VX1000 system is widely recognized by the automotive industry, including vehicle manufacturers and suppliers, it will continue to expand its functions and add new features in the future. Including plans to increase the types of supported processors. Many well-known semiconductor manufacturers have also begun to seek advice from Vector on improving processor architecture to optimize the measurement functions of their products.