现代热水器总存在热水管内残留热水变冷后不便于使用而造成水资源浪费的问题。针对该问题文中提出了一种以STC89C51单片机为核心控制器，DS18B20芯片为温度感应器，五线四相步进电机为控制活塞转向的动力装置，通过单片机控制五线四相步进电机正反转(180？)的运转，以达到控制水流分向的基于单片机的热水器用冷热分流水阀。通过Proteus进行电路的设计和仿真，仿真结果可以实现通过温度的变化来控制步进电机正反转的预期功能；实物化后，测试成功地实现预期目标。
Modern water heaters have the problem
that the residual hot water in the hot water pipe is not easy to use after
cooling, which results in the waste of water resources. This paper elaborates a
kind of Hot and Cold Shunt Water Valve for water heater based on single chip
microcomputer used to control the flow direction of water heater. We take
STC89C51 single chip microcomputer as the core controller, DS18B20 chip as the
temperature sensor and five-wire four-phase stepping motor as the controller of
piston steering. The operation of five-wire four-phase stepping motor (180？) is
controlled by single chip microcomputer. Using Proteus for the design and
simulation of the circuit, the simulation results can realize the expected
function of controlling the forward and backward rotation of the stepping motor
as the change of temperature; and after designing the real object, the test can
successfully achieve the expected goal.
