4.0 Schematic Diagram Of Arduino

CHAPTER 4
HARDWARE DESCRIPTION
4.0 Arduino:
The Arduino Uno is a microcontroller based on the ATmega328. It has 14 digital input/output pins in which 6 can be used as PWM, 6 analog inputs, a 16 MHz ceramic resonator, a USB port, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.[11]
The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter.
"Uno" means one in Italian and is named to mark the upcoming release of Arduino 1.0.[13]
The pin configuration is identicalon all three processors.[12]

4.0.2
Hence the output pin is normally low because, though the IR LED is continuously transmitting, due to no obstacle, nothing is reflected back to the IR receiver. The indication LED is off. When an obstacle is encountered, the output of IR receiver goes low, IR signal is reflected from the obstacle surface. This drives the output of the comparator low. This output is connected to the cathode of theLED, which then turns ON.
Tuned sensitivity of the sensors is limited to the surroundings. Once tuned for a particular surrounding, they will work perfectly until the IR illumination conditions of that region nearly constant. For example, if the potentiometer is tuned inside room/building for maximum sensitivity and then taken out in open sunlight, it will require retuning, since sun’s rays also contain Infrared (IR) frequencies, thus acting as a IR source (transmitter). This will disturb the receiver’s sensing capacity. Hence it needs to be returned to work perfectly in the new