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Fire Bird V ATMEGA2560 Hardware Manual
3. 5V System
“5V System” is used to power various modules of the robots which does not require high
current and where voltage stability is very important. It is used to power logic supply of the
ICs, Sharp sensors , LCD etc. It is the most stable source of the supply on the main board. It
can source 400mA current for the external load.
4. 3.3V Sensor
“3.3V Sensor” is used to power 8 IR proximity sensors, up to 7 white line sensors. In fully
loaded Fire Bird V robot this supply should not be used to power external load having current
requirement more than 100mA.
5. 3.3V Wireless module
3.3V Wireless module supply is used to power XBee wireless module.
6. 3.3V Batt Mon supply
Batt Mon Supply provides 3.3V to the Smart battery monitoring and charger circuit.
Note:
Apart from these four voltage regulators Fire Bird V ATMEGA2560 has two voltage
regulators for powering microcontrollers and servo motors on the microcontroller adapter socket.
3.3.3 Current sensing.
Fire Bird V robot can sense its current consumption using optional Hall Effect current sensor
ACS712 / ACS714.
Figure 3.12: Current sensing in Fire Bird V
Sensor’s current sensing element is located between battery's positive terminal and robot's
electronics. When no current is flowing through the sensor, it gives 2.5V output. This output
value reduces by 185mV per ampere of current flow if 5 Ampere current sensor is installed. If 20
Ampere current sensor is installed then value is reduced by 100mV per ampere. This sensor is an
optional accessory. When this sensor is absent, the sensing path is shorted with 0 ohm resistor or
with a wire. For more information on the sensor operation, refer to its datasheet which is located
in the “Datasheets” folder of the documentation CD.
3.3.4 Battery low indication
Fire Bird V uses smart battery monitoring system based on IC BAT901. When battery voltage
goes below 8V, buzzer starts giving one long beep followed by 2 short beeps with delay of half
second. At the same time red led marked in figure 3.14 starts flashing.
© NEX Robotics Pvt. Ltd. and ERTS Lab, CSE, IIT Bombay, INDIA 22