Electric boiler temperature
system
1.MCU
A microcontroller (or MCU) is a computer-on-a-chip. It is a type of
microprocessor emphasizing self-sufficiency and cost-effectiveness, in contrast to a
general-purpose microprocessor (the kind used in a PC).
The majority of computer systems in use today are embedded in other
machinery, such as telephones, clocks, appliances, vehicles, and infrastructure. An
embedded system usually has minimal requirements for memory and program length
and may require simple but unusual input/output systems. For example, most
embedded systems lack keyboards, screens, disks, printers, or other recognizable I/O
devices of a personal computer. They may control electric motors, relays or voltages,
and read switches, variable resistors or other electronic devices. Often, the only I/O
device readable by a human is a single light-emitting diode, and severe cost or power
constraints can even eliminate that.
In contrast to general-purpose CPUs, microcontrollers do not have an address
bus or a data bus, because they integrate all the RAM and non-volatile memory on the
same chip as the CPU. Because they need fewer pins, the chip can be placed in a
much smaller, cheaper package.
Integrating the memory and other peripherals on a single chip and testing them
as a unit increases the cost of that chip, but often results in decreased net cost of the
embedded system as a whole. (Even if the cost of a CPU that has integrated
peripherals is slightly more than the cost of a CPU + external peripherals, having
fewer chips typically allows a smaller and cheaper circuit board, and reduces the labor
required to assemble and test the circuit board). This trend leads to design.
A microcontroller is a single integrated circuit, commonly with the following
features:
central processing unit - ranging from small and simple 4-bit processors to
sophisticated 32- or 64-bit processors
input/output interfaces such as serial ports (UARTs)
other serial communications interfaces like I²C, Serial Peripheral Interface and
Controller Area Network for system interconnect peripherals such as timers and
watchdog RAM for data storage ROM, EPROM, EEPROM or Flash memory for
program storage clock generator - often an oscillator for a quartz timing crystal,
resonator or RC circuit many include analog-to-digital converters .
This integration drastically reduces the number of chips and the amount of
wiring and PCB space that would be needed to produce equivalent systems using