Specifications
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UV Erasable Programmable ROM (UV EPROM). Both the manufacturing process and characteristics of this
memory are completely identical to OTP ROM. However, the package of this microcontroller has a
recognizable “window” on the upper side. It enables the surface of the silicon chip inside to be lit by an
UV lamp, which effectively erases and program from the ROM.
Installation of this window is very complicated, which normally affects the price. From our point of view,
unfortunately- negative...
Flash memory. This type of memory was invented in the 80s in the laboratories of INTEL and were represented as the successor to the UV
EPROM. Since the contents of this memory can be written and cleared practically an unlimited number of times, the microcontrollers with Flash
ROM are ideal for learning, experimentation and small-scale manufacture. Because of its popularity, the most microcontrollers are manufactured
in flash versions today. So, if you are going to buy a microcontroller, the type to look for is definitely Flash!
Random Access Memory (RAM)
Once the power supply is off the contents of RAM (Random Access Memory) is cleared. It is used for temporary storing data and intermediate
results created and used during the operation of the microcontroller. For example, if the program performs an addition (of whatever), it is
necessary to have a register representing what in everyday life is called the “sum”. For that purpose, one of the registers in RAM is called the
“sum” and used for storing results of addition.
Electrically Erasable Programmable ROM (EEPROM)
The contents of the EEPROM may be changed during operation (similar to RAM), but remains permanently saved even upon the power supply goes
off (similar to ROM). Accordingly, an EEPROM is often used to store values, created during operation, which must be permanently saved. For
example, if you design an electronic lock or an alarm, it would be great to enable the user to create and enter a password, but useless if it is lost
every time the power supply goes off. The ideal solution is the microcontroller with an embedded EEPROM.
Interrupt
The most programs use interrupts in regular program execution. The purpose of the microcontroller is mainly to react on changes in its
surrounding. In other words, when some event takes place, the microcontroller does something... For example, when you push a button on a
remote controller, the microcontroller will register it and respond to the order by changing a channel, turn the volume up or down etc. If the
microcontroller spent most of its time endlessly a few buttons for hours or days... It would not be practical.
The microcontroller has learnt during its evolution a trick. Instead of checking each pin or bit constantly, the microcontroller delegates the “wait
issue” to the “specialist” which will react only when something attention worthy happens.
The signal which informs the central processor about such an event is called an INTERRUPT.
Central Processor Unit (CPU)
As its name suggests, this is a unit which monitors and controls all processes inside the microcontroller. It consists of several smaller subunits, of
which the most important are:
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