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Application Board Overview

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A tour through the features of the Application Board.

Overview

An introduction to the Application Board.
The Make Application Board provides a robust interface between the Controller Board and real world devices. It offers a variety of I/O and connectivity options:

  • 8 analog inputs - 10-bit resolution and circuit protection.
  • 8 high current outputs - up to 1A each. Can be combined to drive DC and/or stepper motors.
  • 4 servo motor outputs - control up to 4 standard hobby servos.
  • 4 status LEDs - provide visual output for your programs.
  • DIP switch and trimpot - for simple manual configuration.

The green screw connectors are slip-on, which means they can be lifted off the board by hand. Devices can be left screwed into the connectors, and removed and replaced without unscrewing. Labels for each of the connectors are printed on the board under the connectors.

appboard_overview.png

Analog Inputs

The Make Controller has 8 10-bit analog inputs.
The Application Board provides 8 analog inputs, to read values from sensors and other input devices. Each input reads voltages from 0 - 3.3V, and converts them to digital values with 10 bits of resolution, giving values from 0 - 1023.

appboard_ains.png
Analog input 7 is normally connected to the trimpot, but you can disconnect the trimpot jumper in order to connect an external input device.


Analog Input Power

Each bank of analog inputs has a voltage/ground pair (VIn and Gnd) on the connector to provide power for input devices you connect to the board. By default, the board is set to provide 3.3V at VIn, but can be easily changed by configuring the voltage select jumper. The voltage for each bank of inputs can be set independently to one of three values: 3.3V, 5V, or V+. The selected voltage will be available at the VIn connector - VIn1 for the first bank and VIn2 for the second.

vselect_in.png

To change the jumper, lift it off the board and replace it facing the label of the voltage you'd like. One side of the jumper must always cover the middle pin.


Set to 3V
 Set to 5V Set to V+
voltage_in_3V.jpg voltage_in_5V.jpg voltage_in_Vplus.jpg

Input Voltages

As the Controller Board runs at 3.3V, each of these inputs accept a 0-3.3V signal. Although the inputs are protected against higher voltages being applied, it's best to avoid applying voltages outside this range. The inputs are rated as 5V tolerant, so you're not likely to damage the board, but the inputs are only sensitive in the 0-3.3V range.

For resistive sensors, this does not pose a huge problem, as you can power your sensor from the 3.3V supply on the board. For devices that explicitly output 5V however, you may need to provide some additional circuitry to arrive at the appropriate voltage.

The circuit below shows a voltage divider that will convert a 5V signal to a 3.3V signal. R1 and R2 are resistors, and must maintain a ratio of 5 to 3.3 to arrive at the correct voltage. For the most precision, R1 should be 20K and R2 should be 39K. Because these values are not so common for resistors, 10K and 15K will also work quite well.

Circuit to convert a 5V signal to 3.3V
5to3divider.png

Digital Outputs

Description of the 8 digital outputs available on the Application Board.
The Application Board provides 8 digital outputs. Digital outputs are capable of sending only two signals - on and off. This kind of control is well suited to devices like relays, lights, valves, and solenoids, to name but a few.

There are 2 banks of 4 digital outs on the Application Board, each driven through a dual half H-driver, with a current rating of 1A per channel. This means you can use the 8 outputs to drive reasonably powerful devices in several different configurations:

Each individual output can control a solenoid, valve, relay, light, or fan.
Adjacent outputs can be paired to control up to 4 DC motors.
Groups of 4 adjacent outputs can be used to control up to 2 stepper motors.

Note: Any combination of these configurations is acceptable. For example, you could mix and match 2 individual outputs, one DC motor, and a stepper motor to make use of all 8 digital outs. Be sure not to try to use outputs for more than one device at a time - a single output cannot, as you might guess, be used simultaneously to drive a DC motor and a stepper motor.

appboard_douts.png

PWM

There are 4 PWM devices on the Controller Board. Each PWM signal is duplicated on adjacent outputs on the Application Board:

  • PWM 0 - digital outs 0 and 1
  • PWM 1 - digital outs 2 and 3
  • PWM 2 - digital outs 4 and 5
  • PWM 3 - digital outs 6 and 7
Each individual output can be independently configured to output the direct PWM signal or the inverted signal.  To control each output completely independently, use it as a Digital Out, instead of a PWM. 


Digital Out Power

Each bank of digtial outs has a voltage/ground pair (VOut and Gnd) on the connector to provide power for output devices you connect to the board. By default, the board is set to provide 5V at VOut, but can be easily changed by configuring the voltage select jumper. The voltage for each bank of outputs can be set independently to one of three values: 5V, V+, or VExt (External Voltage). VExt can be supplied by an external power supply that can be connected at either of the 2-position external power connectors.

The selected voltage will be available at the VOut connector - VOut1 for the first bank and VOut2 for the second.



The output voltage select jumpers.
vselect_out.png



To change the jumper, lift it off the board and replace it facing the label of the voltage you'd like. One side of the jumper must always cover the middle pin.

Set to 5V Set to V+ Set to VExt
voltage_out_5V.jpg voltage_out_Vplus.jpg voltage_out_Ext.jpg

Note: if you don't have a main power supply connected to the board, ie you're running off USB power, there will be no voltage available at the V+ connector.

Servos

A description of the 4 servo controls available on the Application Board.
The Make Application Board can control up to 4 standard servo motors. The servo connectors are marked on the board with the labels Srv0 - Srv3. The 3-spot connectors from hobby servo motors can be plugged directly onto these connectors - be sure that the ground wire on the connector (usually black) is connected to the pin marked Gnd on the board.

appboard_servos.png

Servo Power

Normally, servo motors run on 5V. The Application Board is set by default to power the servos from the 5V line on the board. If you need more power than is available from the power supply on the board, you can configure the servo jumper to power the servos from an external supply. The voltage on the VSrv line is determined by the position of the servo power select jumper - it will either be the 5V line on the board, or the voltage from an external power supply.

To use an external supply, make sure the board is unplugged, and switch the servo jumper so that it is closest to the VExtS ("Voltage External Servo") label on the board. Then connect your external supply to the 2-position external power connector, making sure the polarity is correct. This can be nice as it keeps the 5V line on the board clear from potential noise created by the servos.

Note - the Make Controller Kit cannot draw very much current over a USB connection (about 500 mA at most), so trying to drive servo motors with the board powered only by USB is not a very good idea.

Power

An overview of the flexible power system on the Application Board.

Power can provided to the Application Board from either the main power connector, or the USB connector. Generally, the power from the USB connector is only enough for powering the board itself (great for programming and testing), but not for driving devices more powerful than an LED. To drive anything more than the smallest devices, it is a better idea to power the Application Board from the main power connector using a 9V wall adapter. The board can be run on anywhere from 6 - 12V, but higher voltages mean that the board is doing extra work to produce the 3.3V and 5V lines needed by the onboard electronics.

Be sure that your power supply provides enough current to drive the devices you have connected to the board. Almost all devices and power supplies list a current rating - be sure the combined current of your devices does not exceed the rating of your supply.



appboard_power.png

Serial Port

A 3.3V TTL serial port.
The Make Controller's serial port can be found on the Application Board, just below the JTAG connector.  It consists of 6 pads, spaced 0.1" apart:
  • 3.3V - a connection to the board's 3.3V supply voltage
  • 0V - a ground connection
  • TX - the transmit line from the Make Controller
  • RX - the receive line to the Make Controller
  • RTS - request to send (flow control)
  • CTS - clear to send (flow control)
The Make Controller's serial port provides 3.3V TTL signals.  You'll need a step-up circuit if you want to communicate with RS-232 devices.  Check the how-to here.

User Interface

Several components allow for manual configuration of the Make Controller Kit.

Status LEDs

4 green status LEDs are available to provide visual feedback from your programs.

appboard_leds.png

Dip Switch & Trimpot

The 8-position DIP switch provides up to 256 different values that can be manually selected to alter how your programs behave.

The trimpot provides a single continuous value that can be turned by hand to modify the behavior of your programs.

appboard_trim_dip.png