Wild Thumper Robot Controller
Contents
1. Wild Thumper Robot Controller 2A Current regulation circuitry CAUTION will get hot when recharging Do not touch Left Motor 15A slow blow wey 02 Servod me 4 Servo 1 ia Servo2 Py D8 Servo3 2A DC recharge socket ener ps Hend sAtmega ac is eels i Wa 168 2 Ba meets 44 12C SDA Peoes mt Em ee E meee AS 12C SCL fee oe a TA Bae Len SES j EE DO SerTX RC left power pehsh5hJ e S yen Se eee DI SerRX RC right steer USB port LEDS Battery good LED4 USB RX LED3 USB TX LED2 Power 5V LM1084 G oo S 2 gt SS 2 5V LDO o oo 9A regulator DU q i The Wild Thumper robot controller is an AVR Arduino compatible controller that offers enthusiast the ability to get their robot up and running quickly an easily Although relatively small in size this controller is packed with features Dual 15A continuous FET H bridges with individual fuse protection Current sensing for both H bridges Blown fuse can be detected by processor and indication LED 7 digital I O pins terminated with 3 pin male header allowing servos to plug in directly 5 analog inputs terminated with 3 pin male headers to supply power for sensors 5A LDO regulator to supply power for logic servos and sensors 2A DC power socket for testing programming and recharging SLA NiCd and NiMh batteries can be charged via onboard 2A current regulator Processor can monitor batt2. e from the Tools tab at the top of the window Choose the Nano w ATmega 168 as your board Wild Thumper Controller Arduino 0018 File Edit Sketch yim Help a j a D E Auto Format Ctrl T NS Archive Sketch Fix Encoding amp Reload Serial Monitor Ctrl Shift M include lt Servy include I0pi include Cons Arduino Duemilanove or Nano w ATmega328 Ny Arduino Diecimila Duemilanove or Nano w ATmegal68 Arduino Mega ies See ete ee Arduino Mini AE E NE AAE See eee ee Serer Arduino BT unsigned int Volts LilyPad Arduino w ATmega328 unsigned int LeftAmps LilyPad Arduino wi ATmegal6s unsigned int RightAmps unsigned long chargeTimer unsigned long leftoverload Arduino Pro or Pro Mini 3 3 8 MHz wi ATmega328 Arduino Pro or Pro Mini 3 3v 8 MHz wi ATmegal68 unsigned long rightoverload Arduino NG or older w ATmega168 int highVolts Arduino NG or older w ATmegas int startVolts ATmegas noxtal BMHz int Leftspeed 0 int Rightspeed 0 int Speed int Steer byte Charged 1 j O Flat battery 1l Charged battery int Leftmode 1 j O reverse l brake 2 forward int Rightmode 1 O reverse l brake 2 forward byte Leftmodechange 0 j Left input must be 1500 before brake or reverse can occur byte Rightmodechange 0 f Right input must be 1500 before brake or reverse can occur int LeftPWM PWM value for left motor speed brake int RightPWM PUM value for right motor speed brake
3. efine DServo6 default po The supplied software is programmed for a 7 2V NiCd or NiMh Sub C battery pack and will need changing if other batteries are used Do not use LiPo or Li ion batteries with this charger If you are not sure what batteries you are using then do not use the recharge feature on this board The battery monitoring circuit will report a value of approximately 65 for every volt measured across the battery The lowvolt value represents the voltage at which the controller shuts down to recharge so 410 65 gives a cutoff point of approximately 6 3V The batvolt value is the nominal battery voltage The program uses this to determine the minimum voltage at which delta V can occur As an alternative 6x NiMh or NiCd AA UM 3 batteries could be used Although the Charging circuit is designed to deliver 2A of current it is not recommended for these smaller batteries and can be reduced by reducing the voltage applied to the recharge socket Calibrating Motor Current Readings The controller uses 2 15A slow blow fuses to protect the H bridges These fuses double as current shunt resistors allowing the processor to monitor the current drawn by the motors and protect them from dangerously high stall currents The sample software will shut a motor down if a safe current level is exceeded This should also protect the fuse If a fuse does blow then an indicator LED near the fuse will light up and
4. ernal power is disconnected Using either a PC and the USB port or another processor connected to DO RX and D1 TX the sample software will support these basic serial commands FL flushes the buffer This occurs automatically on power up and if an invalid command is received AN request analog data 10 bytes will be received The high and low byte of analog inputs 1 5 SV followed by the high and low byte of 7 servo positions in uS 14 bytes must be sent HB followed by 4 bytes of data sets the mode 0 2 and power 0 255 of each H bridge Using the Arduino environment The included software also supports basic serial commands for controlling the motors servos and reading analog inputs These features can be accessed using the Arduino 0018 or later programming environment freely available from htip arduino cc The controller cannot be powered directly from the USB port The controller must be powered from batteries or a DC supply 6 12V If using the DC socket then current will be limited via the recharge circuit With the controller powered and connected to a PC via USB cable the program can be easily re configured or edited to suit your needs Download and install the Arduino environment Then open the Wild _ Thumper _Controller pde file To edit the supplied software or upload new software with the Arduino environment you must first select the correct serial port and board typ
5. ery voltage and control recharge circuitry Communicates via USB TTL serial and 12C Can also work with RC and analog inputs Atmega 168 processor with 16K flash memory Arduino AVR compatibility Program via USB or ISP interface Comes preloaded with Arduino boot loader and software This is a low voltage controller and was designed to be powered by a 7 2V sub C battery pack as commonly found in RC cars Higher battery voltages can be used maximum 18V DC but will reduce the maximum current output of the 5V regulator A small CPU fan may be mounted on the heat sink if required Included software The controller comes with the Arduino bootloader and basic software that allows it to be used the moment power is applied The default configuration is as a simple motor controller with a radio controlled receiver plugged into DO and D1 The receiver can be powered directly from the controller Note the signal wire is towards the processor 5V is the center pin and ground is to the outside This applies to all 3 pin headers If you battery voltage gets too low approximately 6V then the controller will shut down to prevent malfunction and the battery charging circuit will turn on With a DC voltage of 3 6V higher than your battery nominal voltage applied to the recharge socket your battery will begin charging until the voltage levels out for more than 5 minutes or peaks delta V at this point the charger will change to a trickle mode until ext
6. int data int servo 7 You will see three tabs at the top of the program labelled Wild_Thumper_Controller Constants h and lopins h The Wild_Thumper_Controller tab contains the main program This can be changed to suit your needs The controller can be the brains as well as the brawn of a robot The Constants h tab stores values such aS communications mode baud rate minimum battery voltage maximum allowable current draw etc The l Opins h tab tells the program which of the processors I O pins are used for what function Take care when modifying the contents of this tab as many functions are hard wired on the PCB Configuring the controller With a few simple modifications to the Constants h tab your controller can be adjusted to accept serial communications charge different batteries and protect different motors from overload For example changing Cmode to a value of 1 will change the communications mode to Serial Change Brate to your preferred baud rate 300 1200 2400 9600 14400 19200 28800 38400 57600 or 115200 Wild_Thumper_Controller Arduino 0018 File Edit Sketch Tools Help OO gt i Wild _Thumper_Controller define Cmode 0 define Brate 115200 define Mix define Leftcenter define Rightcenter define RCdeadband define scale define batvolt define lowvolt define chargetimeout 300000 define Leftmaxamps define Righ
7. the software will register a current level much higher than normal stall currents even at low PWM levels Calibrating the current sensors will require a Multimeter with a 10A range and a stable test load such as a light globe from a car or a high wattage resistor e g 10 ohm 5W or higher Left Motor 15A slow blow Right Motor 15A slow blow Connect the controller to a battery or DC supply by the battery terminals Connect to your computer with the USB cable Load and run the Wild_Thumper_Diagnostic pde program Click on the Serial Monitor icon and set the baud rate to 9600 You will see the load being measured by the processor If you remove the fuses then you will see the current readings jump above 700 This is the highest possible reading Replace the fuses and adjust VR1 or VR2 depending on which motor output you are calibrating Example Your multimeter is connected to the left motor and is reading 940mA You adjust VR1 until the processor reads 47 The left motor is now calibrated with a resolution of approximately 20mA 47x20mA 940mA Your motors have a stall current of 12Amps To protect you motors you decide 11A is the safe limit Set Leftmaxamps in the Constants h tab to 550 11000mA 20mA Set overloadtime to the number of mS required before the motor can restart after an overload occurs The default is 100mS 1 10 of a second
8. tmaxamps define overloadtime lOpins h MODE OF COMMUNICATIONS 222 S2S2S2S22S2SS2S2SSSSSSSSSS SSS SSS SSSSS2S2SSSSSSSSSSSSSSSSS2SSSSSSS2S2SSSESSE2SSSSE2S2 E 2 f Sets communication mode O RC l Serial 2 I2C f Baud rate for serial communications RC MODE OPTIONS ss22ssse2s2sssseseseseeseseseeeeseseseseesesssssessessssssssessseseseeseee e e Set to 1 if L R and F R signals from RC need to be mixed f when RC inputs are centered then input should be 1 5m5 f when RC inputs are centered then input should be 1 5m5 inputs do not have to be perfectly centered to stop motors f scale factor for RC signal to PIM BATTERY CHARGER SETTINGS ss2ssesesesssseseseseseesesesessesesssesessesssesesseseseseeeeee This is the nominal battery voltage reading Peak charge can only occur above this voltage f This is the voltage at which the speed controller goes into recharge mode f If the battery voltage does not change in this number of milliseconds then stop charging t set overload current for left motor set overload current for right motor f time in m5 before motor is re enabled after overload occurs f jJ 222222 2222n SERVO SETTINGS sHesassesssesesessesssessesesesssessesesesessesesssesessesesssesseseseeeee 2 define DServo0 j default pos define DServol default pos define DServo2 j default pos define DServo3 default pos define DServo4 default pos define DServos default pos d
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