RM2C. Understanding Connections on the Robot Control Board (RCB). In the following slides, The RCB components will be documented in detail so that the intended purpose of each part is understood. The Black SPDT switch is used to cut on and cut off the power to the board.
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Understanding Connections on the Robot Control Board (RCB).
The GREY stripe on the DIODE is the NEGATIVE side or “CATHODE”. The POSITIVE side of the DIODE is called the ANODE.
You can see in this photo that I marked the power connector with a + and - sign to be sure I didn’t incorrectly connect power to the circuit. Be sure to screw the terminals down snug to hold the wire in place. Also, be sure that the wires are pushed completely into the sockets with NO insulation showing!
The DISC CAPACITORS in the circuit are used to keep the power source stable so that the voltage doesn’t fluctuate greatly when big loads such as servo motors are powered.
The value of these capacitors is .1 uF. These are SMALL capacitor values designed to handle high frequency shifts.
The power source stable so that the voltage doesn’t fluctuate greatly when big loads such as servo motors are powered. 5 Volt Regulator steps the voltage from the power source down to 5 volts to power most of the essential motors, sensors, relays and actuators that are necessary.
The 5 Volt Regulator can handle 5 AMPS of current and so a HEAT SINK is required to help keep the part cool.
The CENTER ROW of all the header pins is connected to the 5 Volt regulator!
5 volt regulator
The 3.3 Volt Regulator can handle up to 3 AMPS of current and it also requires a HEAT SINK to keep it cool. This regulator gets its power from the 5 volt regulator.
Each set of three header pins is organized with the Propeller Pin Closest to the chip, +5 V in the middle row and Ground in the outside row.
+ 5 Volt
Header Pins are provided on EACH side of the ULN2803 A to allow connections to the chips INPUT and OUTPUT Pins.
A RELAY is an Electromechanical switch that uses a SMALL voltage to control a LARGE voltage. The use of the relay can allow the user to use the 3.3 v output of the PROPELLER CHIP to control devices of 12 Volts and higher.
5 Volt Solid State RELAY
The four 1K RESISTORS shown here are to provide current limiting to pins 12 – 15 where the PS2 Controller is to be connected.
The 10K RESISTOR is being used to provide ISOLATION between the connection on PIN 12 and POSITIVE Voltage.
The XBEE WIRELESS NETWORK CONTROLLER is the device which sends the wireless signal from the PS2 controller to the receiver which is on the ROBOT.
Generally used to control signals in a wireless computer network, the XBEE has its own internal software and can be programmed separate from the Propeller.
The YELLOW (RX) and GREEN (TX) LED’S, beside the XBEE, are used to indicate data transfer.
The XBEE is directly connected to PIN 4 and PIN 3 on the Propeller Chip. These two pins are affected in Propeller Programming and open the communication channel between the two XBEE’s.
The sends the wireless signal from the PS2 controller to the receiver which is on the ROBOT. PROPELLER CHIP shown below is a MICROCONTROLLER that can be programmed to perform many electronics processes at the same time. Although the CHIP itself is NOT labeled, the sticker below the chip shows the actual PIN connections on the PROPELLER CHIP.
This CHIP is the CORE of the ROBOT CONTROL BOARD (RCB). This chip enables the operation of all the robotic parts through computer programming.
The PROP PLUG connects to the 4 PIN HEADER with the silver USB connection faced UPWARD (As Shown)
The last part we will discuss is the 24LC256 EEPROM memory chip. Its purpose is to SAVE the programs that you download onto the Propeller chip for reuse , even if you remove power from the board.
This chip is a FLASH MEMORY device which saves the code you download to the Propeller WHEN you use the F11 key!