DAGU - Rover 5 Explorer PCB w/ 4A Motor Drivers, Encoder Support

DAGU - Rover 5 Explorer PCB

The explorer kit provides the perfect interface between your Rover 5 2WD chassis and your micro-controller with all the hardware you need so you can start programming right away.

It features 2 FET H bridges rated at 4A with current sensing , 5V and 3.3V regulators for Powering Micro Controllers and Sensors and a Servo power supply to power small Servos (for a Pan&Tilt Set up for example).
In addition it includes 4x IR Analog Sensors in the corners, a Charge Circuit for NiMh and NiCd batteries and support for the Rover 5 (2WD) Encoders.

The Explorer PCB includes 4A Motor Controllers with Encoder Support, onboard +5V and +3.3V regulators, 4x IR Sensors and NiMH/NiCd Battery charger. Spacers and Mounting Holes are in place that can fit multiple controllers (Arduino, Arduino MEGA) and Breadboards (not included). The Pan&Tilt Mechanism and IR Compound Eye shown in the picture are Optionally Available.

Power
The Explorer PCB provides 4 different voltage levels for powering your robot.

1. Battery voltage: 7.2V when using NiMh or NiCd batteries is used to power the motors and can also be used to power other motors or circuits.
    
2. Servo Power: Servo’s typically have a voltage rating of 4.5V – 6V. As the battery voltage is too high we use 3x diodes in series to drop the battery voltage to approximately 5.4V. The Diodes are rated at 3A and may get hot when servos are working under heavy loads.
    
3. +5V (Vcc): This voltage is supplied by a Low Drop Out (LDO) regulator which can provide up to 1A even when the battery voltage gets as low as 5.5V. As many development PCB’s need at least 7.5V for their built in regulator you may need to power your processor directly from this regulator. By adding a larger heatsink you can increase the output of this regulator to 1.5A maximum.
    
4. +3.3V: Many newer processors and sensors require a 3.3V supply. We have included a low dropout regulator with a 500mA rating to support these devices. Because some devices such as the encoders require +5V all Vcc connections on the PCB are +5V.
   Motor control and IR LEDs can be driven by 3.3V signals.

 
Motor Control Circuitry

The built in motor control circuitry consist of 2x FET “H” bridges. Each motor control circuit can drive a motor forwards or backwards as well as controlling the speed of the motor using Pulse Width Modulation (PWM).

The motor control circuits each have a maximum continuous rating of 4A and a current sensing circuit that gives an output of approximately 1V per amp. This output can be monitored using a processors analog to digital (ADC) inputs to determine how much load the motor is under and if the motor has stalled.

Each motor is controlled by two digital pins. The Direction pin changes the direction of the motor between forward and reverse. The PWM Speed pin controls the speed of the motor.

    
Encoder Connectors
If your Rover 5 chassis includes encoders then the encoder can be read from the encoder socket. The encoders are powered from the PCB so you only need to read the outputs A and B. Swapping the connections to A and B will reverse the encoders sense of direction.

The output of the encoders consist of 2 square waves that are 90 degrees out of phase. The pattern generated by these outputs can be used to measure speed, direction and distance travelled. A tutorial on how to use these encoders can be found here: http://letsmakerobots.com/node/2403.

  
Infrared Corner Sensors

The explored PCB includes 4 infrared (IR) sensors on the corners which can be used to detect objects or edges depending on the orientation of the sensors.

These sensors are numbered 1 to 4 for easy identification. Each sensor consist of an IR LED and an IR phototransistor. Because you cannot see IR with your eyes a small green LED is connected to each IR LED so you can see when it is on.
To get the maximum range from these sensors, the IR LED and IR phototransistor must be parallel to each other. If you aim the IR LED and phototransistor downward then they can be used to detect the edge of a table or the top of the stairs. Aim the sensors outward for object detection.

These sensors can be used with analog or digital inputs and are intended for indoor / night use only (not under direct sunlight)

 
V1 and V2
 
Power rails V1 and V2 are typically connected to the servo power (5.4V) allowing servos to plug directly into the PCB. These power rails can be disconnected from the 5.4V supply by removing the jumpers on J9 and J18. They can then be connected to the other voltages using J21 and J22.
 

Battery Charging

When the power switch is in the “Off” position the battery is internally connected to a simple trickle charge circuit. When power is connected to the battery charging socket the orange LED will light up.

The Rover 5 includes a 6x AA battery Holder. If you use NiCd or NiMH Rechargeable batteries, these can be recharged by connecting a 9V power supply to the recharge socket.

 
Feature List and Compatibility:

• 2x FET “H” bridge motor drivers rated at 4A with current sensing.
• 5V LDO regulator rated up to 1.5A with suitable heatsinking.
• 3.3V LDO regulator rated at 500mA.
• Servo power supply – 5.4V rated at 3A assuming the use of 7.2V battery.
• 4x IR analog/digital sensors mounted on the corners.
• 2x individual power rails (V1, V2) that can be connected to any voltage.
• Built in trickle charge circuit for NiMh or NiCd batteries. (DO NOT use with LiPo.)
• Mounting holes for hardware including Arduino and Arduino Mega PCBs.
• Compatible with Rover 2WD models only (models with and without encoders)
  

• 1x Explorer PCB for Rover 5
• 1x Set of Hex Brass Spacers
  (for fitting additional boards and accessories such as Arduino, Breadboards, etc.)
   
• Explorer PCB Instructions Manual

*The Pan&Tilt Mechanism with Servos and IR Compound Eye shown in the picture are Optionally Available (not included in the kit).

Please note this is the Explorer PCB only. The Rover 5 and Microcontroller (such as Arduino, Arduino MEGA, PIC or other) much be purchased separately.