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OT-Proto1 Shield KIT .... < Requires Assembly >
-- "The Vulcan Proto Shield" --

  • download OT-Proto1 Schematics.
  • see Construction Info.

    Temporary Ordering: contact us via email at < othobbies@yahoo.com >

    OT-Proto1 Kits are for makers who like to build their own gear. The -MINIMUS Kit has minimal number of parts, and the -MAXIMUS Kit includes a full complement of parts.

  • OT-Proto1 - MINIMUS Kit, $20.95 USD - (60 parts total)
  • OT-Proto1 - MAXIMUS Kit, $28.95 USD - (90 parts total)
  • see -MINIMUS, -MAXIMUS Parts Lists

    OT-Proto1 Shield KIT - UNO-compatible header arrangement

  • 3.4" x 2.9" industrial-quality pcb - (heavy 50-mil buss traces).
  • big TO-220 1.5-Amp regulator, with heatsink - nominal 5V [adjustable 1.2-37V].
  • big DPAK 3.3V 1-Amp regulator.
  • standard Arduino-UNO stacking headers.
  • Extension Headers - 3-row male (signal-power-gnd) on all I/O pins, electrically separate from Arduino header pins (see below).
  • layout for series-protection Rs and voltage dividers on all I/O lines.
  • large prototyping area, over 300 pads, with power and ground busses.
  • RF - layouts for XBee socket, RFM12/22 (smt pads), header for nRF2401.
  • pre-wired socket for SPI SRAM or EEPROM.
  • LM386 audio amplifier layout.
  • misc - 3 Leds, 2 pushbutton switches.
  • see also Special Features below.
  • [OT-Proto1]
    + enlarge

    Use the prototyping area for signal-conditioning, opAmps, extra A/D or D/A converters, h-bridges, memory storage chips, even another ATmega328 chip. The next page shows some OT-Proto1 Example Projects which illustrate the versatility of the shield.
    Proto Shield Comparisons

    This table shows how the features of the OT-Proto1 Shield compare to several other popular proto shields - and what you get for your money. These are largely build-it-yourself boards, and most common proto shields include a few generic parts, and have little dedicated layout.

    With the OT-Proto1 Shields, you get much more on-board capability with most of the basic pcb circuitry laid out already, as well as most parts included with the kits, so a lot of time can be saved from having to build up common circuitry, and money can be saved from tracking down and ordering parts.

    p/n
    #parts
    Voltage
    Regulators
    Power
    Jack
    Extension
    Headers
    I2C Buss
    RF-capable (XBee, RFMxx, nRF2401)
    Audio
    Amp
    SRAM
    layout
    price
    OT-Proto1
    60,90
    5V, 3.3V
    Y
    3x20
    3x4
    Y, Y, Y
    Y
    Y
    $21-29
    PROTO SHIELDS WITH WIRELESS
    Arduino Wireless Proto Shield
    17
    - , 3.3V
    -
    -
    -
    Y, - , -
    -
    -
    $20-24
    Arduino Wireless/SD Proto Shield
    28
    - , 3.3V
    -
    -
    -
    Y, - , -
    -
    -
    $25-28
    sparkfun Xbee Shield
    24
    - , 3.3V
    -
    -
    -
    Y, - , -
    -
    -
    $25
    PLAIN PROTO SHIELDS
    Arduino Proto Shield
    7
    - , -
    -
    -
    -
    - , - , -
    -
    -
    $15
    adafruit 51
    15
    - , -
    -
    (1x15)
    -
    - , - , -
    -
    -
    $15
    adafruit 196 Screw Shield
    15
    - , -
    -
    (1x36)
    -
    - , - , -
    -
    -
    $16
    Maker Shed
    19
    - , -
    -
    1x12
    -
    - , - , -
    -
    -
    $17
    Tinkerkit
    25
    - , -
    -
    3x12
    1x4
    - , - , -
    -
    -
    $14
    sparkfun 7914
    15
    - , -
    -
    -
    -
    - , - , -
    -
    -
    $10
    - means not included.
    (.) means header strips are included, but no specific extension header layout.

    Summary of OT-Proto1 Shield Layouts

  • complete layouts for TO-220 and 3.3V DPAK regulators, with filter caps.
  • standard Arduino stacking-header layouts.
  • complete 3-row Extension Header layouts, for all 20 I/O pins - ready for customization.
  • extra 3-place I2C buss layout.
  • prototyping area layout, with ground and power busses.
  • jumpers for selection of buss voltages - inc proto area, analog+digital Extension Headers, I2C buss.
  • complete XBee module layout, with level-shifters & UART selection jumper header.
  • partial RFM12/22 transceiver module smt layout.
  • customizable nRF2401 transceiver module layout.
  • basic LM386 audio amp layout.
  • complete DIP8 SRAM/eeprom layout.
  • layouts for 3/ea Leds & current-limiting resistors.
  • layouts for 2/ea pushbutton switches.


    Special Features

    1. Non-interference with Arduino board metal USB connector. With some shields, there is an interference problem in that the USB connector metal shell on the Arduino board sticks up and shorts out circuitry on the shield. You cannot push the shield down all the way into the stacking header pins. In contrast, the OT-Proto1 Shield was designed so there is no circuitry directly over the USB connector to short out.

    2. Big Voltage Regulators. Most Arduino boards have dinky surface-mount (smt) voltage regulators, that will quickly overheat if Vin is more than about 7V and the load currents are more than 200 mA or so. Also, many Arduino boards can supply only about 50 mA of current at 3.3V. In contrast, the OT-Proto1 Shield has its own 5V [adjustable] & 3.3V regulators that can provide upwards to 1 Amp of current without overheating.

    For added heat dissipation, a heatsink can be installed beneath the TO-220 regulator. Likewise, the 3.3V DPAK smt regulator has top and bottom pcb areas for heatsinking. See the regulator power dissipation page for details.

    The output voltage of the TO-220 voltage regulator on the OT-Proto1 Shield can be adjusted to different levels. See the regulator hacking page for details.

    3. Arduino I/O Pin Protection. The single point on Arduino chips most susceptible to accidental damage are the 20 or so I/O pins. Application of voltage > 5V to a chip with Vcc=5V can permanently damage the chip. And people do this all the time.

    The simplest way to safeguard against this is to use small-valued Rs in series with the I/O pins, eg 150-330 ohms - these work in conjunction with the internal clamping diodes on the Arduino chip pins to limit overvoltage damage. The series-Rs actually protect against voltages > Vcc and < 0V, and also short-circuits on the pins. The OT-Proto1 Shield allows series-Rs to be easily wired to all Arduino I/O pins.

    4. SPI SRAM or EEPROM Chip. Arduino program sketches most commonly run out of SRAM before anything else, such as code space. The ATmega328 chip on the Arduino-UNO has only 2 KByte of RAM. The OT-Proto1 Shield has a socket to mount an SRAM chip (23LC1024) that will provide an additional 128 KBytes of SRAM, and which can be accessed at upwards to 500 KBytes/sec using SPI commands.

    Alternatively, a 128 KByte SPI EEPROM chip (25LC1024) can be plugged in. Both chips will run at either 5V or 3.3V, and there are Arduino libraries available for both - see Arduino Playground.

    5. RF Transceiver Mounting. The OT-Proto1 Shield can directly mount many types of XBee-compatible transceivers, as well as NordicSemi nRF2401 and HopeRF RFM12/RFM22 transceivers. There is a 2mm socket layout for the XBee devices, surface-mount pads for the RFMxx devices, and an 8-pin header for the nRF2401 devices.

    These devices all operate at 3.3V only, and cannot be powered from 5V. Many host Arduino boards cannot supply enough current at 3.3V for the higher power XBee devices, but the 1A regulator on the OT-Proto1 Shield can easily power any of these devices.

    The RFMxx and nRF2401 devices interface to the Arduino SPI peripheral, while the XBees connect to the Arduino Rx/Tx pins. There is a special jumper-block, as well as built-in level-shifters, on the Proto1 board to interface XBees. See the OT-Proto1 schematic and RF Module Info page for more details.

    6. Audio Amplifier. The OT-Proto1 Shield includes the basic layout for an LM386 audio amp chip, as well as associated Rs and Cs, plus a 2-pin 3.5mm terminal block to connect an external speaker. The LM386 inputs can be jumpered to Arduino I/O pins or other audio sources.


    Interfacing

    Arduino Stacking-Headers. The OT-Proto1 Shield has standard Arduino-UNO style female stacking-headers, so other Arduino shields can be mounted on top.

    In addition, the 300 pad prototyping area is available for adding just about any circuitry desired for custom applications, including signal-conditioning, opAmps, D/A or extra A/D converters, h-bridge chips, MOSFET switches, etc.

    Extension Headers. The additional 3-row 0.1" male headers allow up to 20 external devices, such as sensors, sonars, R/C servos, and other devices to directly plugged into, and powered from, the OT-Proto1 Shield - (note that: Arduino-UNO libraries support only up to 12 servos). And of course, additional headers and connectors can be wired into the proto area.

    The Extension Headers use an industry-standard signal-power-ground arrangement. The middle-row "power" busses allow the OT-Proto1 Shield to power external devices from the onboard 5V [adjustable] and 3.3V regulators; there are also extra header pins so external voltage sources, such as batteries, can be used to power the middle rows.

    The Arduino stacking-headers and 3-row Extension Headers are electrically separate from each other, and can be wired together in different ways, eg via series-Rs or voltage-dividers (see diagram at right, and OT-Proto1 schematic for complete details). This makes it easy to: (a) protect the Arduino I/O pins, (b) interface to voltage levels other than 0..5V, and (c) interpose circuitry between the two sets of headers, such as opAmps wired into the proto area.

    Several vendors sell cables and/or special receptacles for plugging into 0.1" male headers. For more info,
    see the
    3-Row Header Interfacing page.

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    © OT-Hobbies, April 2013, updated May 2013