Implementation of Dip Test In Microcontroller-Based Operations Control System |
Microcontrollersusually contain from several to dozens of general purpose input/output pins(GPIO). GPIO pins are software configurable to either an input or an outputstate. When GPIO pins are configured to an input state, they are often used toread sensors or external signals. Configured to the output state, GPIO pins candrive external devices such as LEDs or motors. Manyembedded systems need to read sensors that produce analog signals. This is thepurpose of the analog-to-digital converter (ADC).Since processors are built to interpret and process digital data, i.e. 1s and0s, they are not able to do anything with the analog signals that may be sentto it by a device. So the analog to digital converter is used to convert theincoming data into a form that the processor can recognize. A less commonfeature on some microcontrollers is a digital-to-analog converter (DAC) thatallows the processor to output analog signals or voltage levels. Inaddition to the converters, many embedded microprocessors include a variety oftimers as well. One of the most common types of timers is the Programmable Interval Timer (PIT). APIT may either count down from some value to zero, or up to the capacity of thecount register, overflowing to zero. Once it reaches zero, it sends aninterrupt to the processor indicating that it has finished counting. This isuseful for devices such as thermostats, which periodically test the temperaturearound them to see if they need to turn the air conditioner on, the heater on,etc. Time Processing Unit (TPU) is a sophisticatedtimer. In addition to counting down, the TPU can detect input events, generateoutput events, and perform other useful operations. Adedicated Pulse Width Modulation (PWM) block makes itpossible for the CPU to control power converters, resistive loads, motors,etc., without using lots of CPU resources in tight timer loops. Universal AsynchronousReceiver/Transmitter (UART) block makes it possible to receive and transmitdata over a serial line with very little load on the CPU. Dedicated on-chiphardware also often includes capabilities to communicate with other devices(chips) in digital formats such as I2C and Serial Peripheral Interface (SPI).