The development of automotive electronic controllers (ECUs) and the development process of any electronic products are basically the same, and engineers in hardware, software, and testing are required to complete.

In the design process, it is generally divided into functional samples, test samples (generally two rounds or more), and mass production parts. The main tasks of the prototypes at different stages are different, and the focus of design and testing will be different.

If you have experience in hardware development, you can skip this paragraph and go straight to the end.

Hardware design flow of automotive electronic controller (ECU)

First, the hardware design

1. Project needs analysis

The analysis of project requirements is the first step in the design task. A complete project requirement generally includes the functions of the controller, MCU performance requirements, external electrical architecture, working environment, installation location, working environment, operating voltage range, and external load. Parameters, diagnostic requirements, target costs, etc. With this content, developers can design according to their own content, of course, project requirements are a thing that changes from time to time, and this change is also one of the sources of pain in hardware design.

2. Hardware overall design and device selection

According to the external load and interface requirements, the overall hardware solution can be determined: several ADCs, several digital inputs, several CANs, several LINs, several high and low side drivers, and so on. Then select the device according to the number of interfaces required. Here, factors such as cost, platform maturity, chip supplier cooperation, and supply cycle should be considered. In a mature company, there will be some mature platforms for different applications (similar to the platform of the whole vehicle). For example, the body controller selects 16 chips and the car selects 32 chips. If the project cost card is very strict, it may be necessary to play the creativity of the hardware engineer, and use the triode resistor and capacitor to make a powerful circuit.

3. Schematic design, structural design, PCB design

After the device selection is completed, the schematic design can be started after the components are completed. According to the project requirements and their own experience, the schematic and the peripheral circuits of the chip are refined. In addition to considering the function implementation, it is also necessary to pay attention to the fault. Diagnostics, electrical performance and electromagnetic compatibility related issues: anti-static, signal integrity, external load power, anti-reverse connection, anti-power failure, anti-abnormal voltage and many other details, this piece is to see the accumulation of experience.

At this stage, the structural engineer also needs to intervene to determine the material, size, internal structure of the controller casing according to the installation position, space, and waterproof rating requirements of the controller. The mechanical properties, waterproof and dustproof points are mainly considered according to environmental test requirements. .

After the schematic and structure are designed, the design outputs to the PCB engineer for PCB design. The PCB design focuses on layout and heat dissipation. At this point, you need to organize the BOM and arrange the preparation. Release production materials upon completion.

4. Function debugging

After the PCB is sampled, the software engineer intervenes to perform function debugging to ensure the most basic input and output functions and discover problems in the hardware design. The hardware engineer is now preparing for revision.

5. Design verification DV test

After the revision of the 1-3 steps, the DV test is started, and the test conditions are prepared according to the national standard and the test environment and equipment are prepared. Then continually modify to meet the criteria.

After the above five parts, the hardware work basically comes to an end, and the rest is mainly based on the requirements and software requirements to follow up and modify. Of course, sometimes the requirements of the main engine factory, may also need to do product approval test, issued some test reports, this is similar to DV, does not expand.

Add a little, for mass production projects, downline detection is also a very important step, the corresponding offline detection equipment and software are required, and the corresponding program is programmed when the line is offline, so the hardware engineer must design it. Pay attention to the quality and coverage of the test points, and support the development of offline detection equipment.

In general, the automotive electronic hardware development process is actually the same as the process in the consumer electronics field, but it takes a little more effort in the DV test. The focus of automotive electronics is on safety, and functional safety is also becoming popular. In order to meet these requirements, the test conditions for automotive electronics are becoming more stringent.

The complexity of the working environment of the car: the power supply voltage is unstable, the working temperature is wide, and the working environment is very disturbed. These need to be considered in the design and test. The specific situation will not be carried out for a while, and there will be opportunities to write electrical performance tests and Emc test related things.

It may be boring or less valued in many fields and company hardware engineers, but I feel that the hardware in the automotive electronics field may be more fun than the consumer electronics field. The quality of the peripheral circuits sometimes directly determines the reliability of the ecu. The high temperature characteristics of a diode in a controller of a company used to cause a batch of vehicles to recall. Therefore, the responsibility of hardware engineers in the automotive industry is also very heavy.

Of course, if the hardware engineer can understand the software, communication protocols, troubleshooting, etc., it is easier to carry out the work.

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