eChook GPT Documentation
  • Welcome to the eChook nano documentation
  • System Overview
  • The eChook Nano Kit
    • Versions
  • Build Instructions (Kit V1.x)
    • Build Steps Photos
    • First Power On
  • Build Instructions (Kit V2+)
  • Programming the Arduino
    • Install Arduino IDE
    • Arduino Drivers
    • Download the eChook Arduino Code
    • Programming the Arduino
  • Setting up the Bluetooth
    • Pairing with a phone
  • Connecting the eChook to the Car
    • Power and Voltage
    • Current Sensor
    • Throttle Input
    • External Buttons and Brake
    • Temperature Sensors
    • Wheel and Motor RPM
    • PWM Output
  • Calibrating the eChook
    • Wheel Speed and Motor RPM
    • Temperature
    • Voltage
    • Current
  • Using the App
    • Pair eChook to Phone
    • Setting up the App
    • Logging Data
    • Lap Counting
  • Telemetry (Live Data)
    • eChook Live Data
    • Node-Red Integration
    • DIY Web Dashboard
  • Using the Data
  • Circuit Schematics
    • 12 and 24v Inputs
    • Temperature Inputs
    • Bluetooth Module
    • Throttle Input
    • Current Input
    • Button Inputs
    • RPM Inputs
    • PWM Output
    • Power Regulator
    • Expansion Port
  • All about the Arduino nano
    • The eChook nano Code
  • Bluetooth Communication
    • Bluetooth Packet Encoding
    • Bluetooth Packet Decoding
  • Experimental Section
    • GUI Calibration
  • eChook Accessories
  • DIY eChook
  • Spare Parts
  • Troubleshooting
  • Contributing
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  1. Circuit Schematics

12 and 24v Inputs

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Last updated 6 years ago

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Each of the battery voltages need to be stepped down so that in worst case the voltage seen at the arduino won’t exceed 5v. To achieve this a potential divider was chosen to step 30v down to 5v. Each voltage input uses the same component values.

Resistors R1 and R2 above form the potential divider.

C3 is a ceramic capacitor forming a low pass filter with R1 and R2 to remove any high frequency component from the voltage signal. On a greenpower car the motor will produce small high frequency voltage spikes as the brushes connect and disconnect from the commutator, the low pass filter removes these from the signal reaching the arduino.

BattTotalVTP represents the multimeter test point on the back of the PCB, giving easy access to check the voltage output from the potential divider with a multimeter or oscilloscope.

The circuit to the right is identical, but takes the lower battery voltage as an input.