28123 Parallax Inc, 28123 Datasheet - Page 323

• Manufacturer Part Number: 28123
• Description: TEXT WHAT'S A MICROCONTROLLER
• Manufacturer: Parallax Inc
• Type: Programmingr

Specifications of 28123

• Style: Book
• Title: What's a Microcontroller?
• Contents: Whats a Microcontroller? Text
• Product: Microcontroller Accessories
• Core Processor: PIC16C57c
• Flash: 128 Bytes
• Operating Supply Voltage: 9 V
• Board Size: 31 mm x 16 mm
• Lead Free Status / RoHS Status: Not applicable / Not applicable

Appendix F: More about Electricity
What’s an Electron? An electron is one of the three fundamental parts of an atom; the
other two are the proton and the neutron. One or more protons and neutrons stick together
in the center of the molecule in an area called the nucleus. Electrons are very small in
comparison to protons and neutrons, and they orbit around the nucleus. Electrons repel
each other, and electrons and protons attract to each other.
What’s Voltage? Voltage is like electrical pressure. When a negatively charged molecule is
near a positively charged molecule, the extra electron on the negatively charged molecule
tries to get from the negatively charged molecule to the positively charged molecule.
Batteries keep a compound with negatively charged molecules separated from a compound
with positively charged molecules. Each of these compounds is connected to one of the
battery’s terminals; the positively charged compound is connected to the positive (+)
terminal, and the negative compound is connected to the negative (-) terminal.
The volt is a measurement of electric pressure, and it’s abbreviated with a capital V. You
may already be familiar with the nine volt (9 V) battery used to supply power to the Board of
Education or HomeWork Board. Other common batteries include the 12 V batteries found in
cars and the 1.5 V AA batteries used in calculators, handheld games, and other devices.
What’s an amp? An amp is the basic unit of current, and the notation for the amp is the
capital ‘A’. Compared to the circuits you are using with the BASIC Stamp, an amp is a very
large amount of current. It’s a convenient value for describing the amount of current that a
car battery supplies to headlights, the fan that cool a car’s engine, and other high power
devices.
What’s Resistance? Resistance is the element in a circuit that slows down the flow of
electrons (the current) from a battery’s negative terminal to its positive terminal.
The ohm is the basic measurement of resistance. It has already been introduced and it’s
abbreviated with the Greek letter omega (Ω).
What’s a Conductor? Copper wire has almost no resistance, and it’s called a conductor.
What’s Charge? The tendency for an electron to repel from another electron and attract to
a nearby proton is called negative charge. The tendency for a proton to repel from another
proton and attract an electron is called positive charge.
electrons than protons, it is said to be negatively charged. If a molecule has fewer electrons
than protons, it is said to be positively charged. If a molecule has the same number of
protons and electrons, it is called neutrally charged.
What’s Current? Current is a measure of the number of electrons per second passing
through a circuit. Sometimes the molecules bond in a chemical reaction that creates a
compound (that is neutrally charged).
charged molecule and joins the positively charged molecule by passing though a circuit like
the one you just built and tested. The letter most commonly used to refer to current in
schematics and books is capital ‘I’.
Other times, the electron leaves the negatively
When a molecule has more