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Home > Control / MCU > Analysis of the solution of automobile MCU instrument

Analysis of the solution of automobile MCU instrument

Published time: 2019-12-20 11:00:15

Renesas technology was founded in April 2003 by the merger of Hitachi manufacturing and the semiconductor division of mitsubishi electric to provide semiconductor solutions for mobile communications, automotive electronics and PC/AV(digital home appliances).In the global automotive semiconductor market, renesas has 7.1% of the market share, ranking the fourth;It occupies the first place in the Japanese market, with a market share of 22.3%.Its automotive semiconductor solutions cover five areas: safety, information, powertrain, chassis, and bodywork, each with multiple solutions.

Automotive instrumentation solutions

The characteristics of instrument MCU are as follows:

1. Embedded stepper motor PWM controller: it can directly control and drive 4-6 stepper motors without external driver IC, so it can save cost and layout space, and has excellent EMI/EMC performance;

2. Embedded LCD controller: 28/32 segment 4 common pin can directly control LCD, and no external drive IC is needed, so it can save cost and layout space, and has excellent EMI/EMC performance;

3. High-speed CPU: single instruction cycle, the minimum instruction execution time of H8S at 20 MHz is 50ns, while the minimum instruction execution time of H8SX at 40 MHz is 25ns;

4. Powerful timer: the on-chip 16-bit timer pulse unit has three 16-bit timer channels, including input capture, output comparison, PWM and phase calculation.

H8S/228X special module basic functions, including three parts: timer pulse unit (TPU);Stepper motor PWM controller and LCD controller.

TPU is composed of 3 16-bit timer channels, including up to 8 pulse input/output channels.Input capture function;Counter reset operation;Synchronous operation;Timer counter can write at the same time;Can compare match and input capture simultaneously clear zero;Simultaneous input/output of register is realized by synchronous counter operation;Maximum 7 phase PWM output combined with synchronous operation.

Stepping motor PWM functions include: maximum 16 pulse output, including two 10-bit PWM channels, each channel has 8 output, can be directly independent control of 4 stepping motor;0% to 100% duty cycle;5 operating clocks;High-speed access can be achieved through the 16-bit bus interface;Two interrupt sources;You can set the module stop mode.

For LCD controller/driver, its important functions are: 28/32 segment 4 common pin;Segment output pins can be used as 4 groups of ports for 11 frame frequencies.A or B waveforms can be selected by software;Built-in power supply separation resistor;In addition to standby mode and module stop mode, there is operation mode display.

Dashboard application solutions

1. Micro-stepping motor solution

The micro-stepping motor has the advantages of low cost, simple structure, high reliability, no maintenance and no feedback components.But the resonance effect often occurs at low speeds, and the torque decreases as the speed increases.Figure 1 shows the internal structure of the VID stepping motor, where the left is the rotor, the middle is the gear, and the right is the motor output.

2. Motor drive mode

Motor drive mode has step drive mode and micro - step drive mode.FIG. 2 shows the time-series diagram driven by steps. It can be seen that a cycle is composed of six steps.Conversely, if the pulse train is from right to left, the pointer rotates counterclockwise.Figure 3 shows the timing diagram of micro-step driving mode, where the blue line represents the current of the left coil and the red line represents the current of the right coil.There are 24 micro-steps in a cycle, and the current waveform on the coil is similar to the sine wave pattern.

Renesas dashboard solutions

FIG. 4 shows the solution block diagram of renesas H8S/228X dashboard. On the left is the voltage input, including fuel, temperature and so on.Pulse input, including the tachometer and speed, the block diagram gives each functional module.On the right side of the picture are 4 step motor, PWM dimmer, CAN and LCD.

Figure 5 shows a block diagram of the H8SX/1544 dashboard solution.On the left side of the diagram is the voltage input, including fuel, temperature, etc.There are pulse inputs, including tachometers and speeds, E2PROM and PC.Block diagram gives each functional module;On the right side of the picture are 4 step motor, speaker, 2 step motor, PWM dimmer, CAN1, CAN2 and LCD.

The development tools for H8S/228X include compilers, assemblers and linkers, as well as debuggers and simulators;Hardware includes emulator, JTAG emulator, evaluation board and CPU board.



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