Current Sensor - NEX ROBOTICS Fire Bird V ATMEGA2560 HEXAPOD User Manual

Fire Bird V ATMEGA2560 Hexapod Robot User Guide
Figure 4.1 Servo Control Board
4.4.1 Servo connection and supply
Each servo motor requires Vcc, Ground and position data encoded in the form of PWM. Servo
comtrol card can interface 20 servo motors at a time. Power given to these servo motors can be
turned on/off by controlling relay which is connected to the PD0 of the ATMEGA2560
microcontroller. When relay is turned on, "RLY PWR" LED is also turns on. "SEVRO PWR"
LED indicates power across servo motors.
4.4.2 Smart Battery Protection Circuit
Smart Protection Circuit board shows battery level in 4 steps and gives audio warning if battery
is discharged below critical level.
Indications on Smart Protection Circuit Board:
Battery voltage above 7.41V: Blue LED on
Battery voltage between 7.4V and 6.8V: Blue LED blinks
Battery voltage between 6.8 and 6.6V: Red LED blinks
Battery voltage below 6.6V: Red LED blinks and Buzzer beeps

4.4.3 Current sensor

ACS714, 20Amp Hall Effect current sensor is used to measure current consumed by the 18 servo
motors. It is an optional accessory. It gives out 100mV per ampere of current. Analog output of
the current sensor is connected to the PORTF 5 (ADC5) pin of the microcontroller. ADC5 is also
connected to IR Proximity sensor 2. In order to sense the current sensor's output you need to
nd
disconnect IR Proximity sensor 2 from the ADC5. This can be done by removing 2 jumper
from the left of the J2 on the microcontroller adaptor board. For location of the J2 refer to figure
3.58 in the Hardware Manual.
© NEX Robotics Pvt. Ltd. and ERTS Lab IIT Bombay, INDIA 19