Hardware circuit microcontroller system consists of two parts: First, when the system is extended, i.e. MCU internal function units, such as ROM, RAM, I / O, timer / counters, interrupt system does not meet the requirements of the application system must be in the extended off-chip, chip select appropriate, the corresponding circuit design. Second, the configuration of the system, i.e. the system configuration according to the functional requirements of the peripheral devices, such as keyboards, monitors, printers, A / D, D / A converter, etc., to design a suitable interface circuit.
And expansion of the system configuration should follow the following principles:
1. Select a typical circuit as much as possible, and in line with SCM conventional usage. Standardized hardware systems, modular lay a good foundation.
2, disposed horizontally and peripheral system expansion should fully meet the functional requirements of the application system, and leave a suitable margin to the second development.
3, the hardware architecture should be combined with application software solutions to be considered. Hardware architecture and software programs are likely to affect each other, the principle consideration is: software that can be realized as far as possible by the software, to simplify the hardware structure. It must be noted, implemented by software and hardware features, the general response time is longer than the realization of hardware and CPU time.
4, the system associated device performance as closely as possible to do. Such as the choice of single-chip CMOS chip constitute low-power system, the system should all chip select low-power products as much as possible.
5, reliability and jamming design is an integral part of the hardware design, which includes a chip, device selection, decoupling filter, printed circuit board traces, channel isolation.
6, when many single-chip peripheral circuits, we must consider its drive capability. Insufficient driving capability, the system is not reliable, the bus load can be reduced through the addition of enhancing the driving capability of the line driver chip or reduce power consumption.
7, try to design hardware systems towards "chip" direction. The more system components, mutual interference between the device and the stronger, the power consumption increases, inevitably reduces the stability of the system. With the integrated microcontroller chip more powerful, true system-on-chip SoC been able to achieve, such as ST company recently introduced μPSD32 ×× products on a single chip integrates a 80C32 core, high-capacity FLASH memory, SRAM, A / D, I / O, two serial ports, watchdog, power-on reset circuit or the like.
(Zero-based electronic product design)
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