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Electronics and Robotics LLC www.ootbrobotics.com
Epiphany DIY Users Manual v2.0
Last Updated January 25, 2013
Electronics and Robotics LLC www.ootbrobotics.com
Electronics and Robotics LLC www.ootbrobotics.com
WARNING READ BEFORE USE !!!
1) DO NOT OVERLOAD OR SHORT POWER RAILS. out of the Box is not responsible
for any damage to personal property through the use of the uTinkerer development platform.
Use at your own risk. ALWAYS check for power and ground connectivity on all power rails before
powering the Epiphany DIY robotics platform. Short circuits on any of the power rails can result in
irreversible damage to the Epiphany DIY as well as any device connected to it, this includes a
personal computer connected over USB. In addition to checking for short circuits the user should
also consult the electrical specifications portion of this manual before interfacing any device with the
Epiphany DIY robotics platform.
2) DO NOT BEND THE BOARD. The Epiphany DIY robotics platform should never be bent or
exposed to ANY bending force. The Epiphany DIY consists of a 6 layer PCB. Bending can cause
undue strain on the copper traces of the PCB. This strain can result in unpredictable behavior and or
failure of the device.
3) Do not touch the switching regulator @U?. This component generates the 3.3V power rail used my
many of the components. Touching the regulator U? can result in the 3.3V becoming unstable, which
may cause irreversible damage to the Epiphany DIY. Heat shrink insulation may be applied, to
isolate the regulator
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Table of Contents WARNING READ BEFORE USE !!!...................................................................................................... 3
Use of This Document .............................................................................................................................. 6
Basic Features ........................................................................................................................................... 7
Analog ................................................................................................................................................... 8
Configuring the Epiphany for 5V Analog Signals ............................................................................ 8
Analog Input Voltage Level Selection .............................................................................................. 8
Character LCD Port .............................................................................................................................. 9
Table 1 LCD Pinout .................................................................................................................. 9
USB Serial Port ................................................................................................................................... 10
Programming Via the USB Bootloader .......................................................................................... 10
Figure 1 USB-Boot Jumper ..................................................................................................... 10
XBee Wireless Adapter ....................................................................................................................... 11
Add-On Package Features ....................................................................................................................... 12
DC Motor Packages ............................................................................................................................ 13
Built In Thermal and Current Protection ........................................................................................ 13
High and Standard Power Configurations....................................................................................... 13
Dual ................................................................................................................................................. 13
Quad ................................................................................................................................................ 13
Servo Packages ................................................................................................................................... 14
Servo Safe Timeout Function ......................................................................................................... 14
Servo Package ................................................................................................................................. 14
Servo + Package .............................................................................................................................. 14
Getting Started ........................................................................................................................................ 15
Basic Connections ............................................................................................................................... 16
Basic Power Connections.................................................................................................................... 17
Figure 2 Color Key ................................................................................................................. 17
Programming the Epiphany DIY ........................................................................................................ 18
Bootloader Programming ................................................................................................................ 18
JTAG/PDI Programming ................................................................................................................ 18
Appendix ................................................................................................................................................. 19
Glossary .............................................................................................................................................. 19
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Electrical Specifications ...................................................................................................................... 21
Table 2 Basic Unit Electrical Specifications ........................................................................... 21
Table 3 Motor Driver Electrical Specifications ...................................................................... 21
Table 4 Servo Controller Electrical Specifications ................................................................. 22
Device List and Related Documentation............................................................................................. 23
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Use of This Document
The Epiphany DIY robotics platform was designed with emphasis towards hobby and educational use. In
kind this document was crafted towards readers who may be unfamiliar with microprocessors,
microcontrollers etc. Many technical and obscure terms encountered in this document are defined in the
Glossary. Often as well links are provided to sources of greater detail.
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Basic Features
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Analog
The ATxmega128A1U and many other
microcontrollers of its generation have moved to
lower voltage inputs to their analog to digital
converters (ADCs). Speculating, this is likely due to
the desire for higher resolutions and conversion
speeds. Such specifications are more easily attained at
lower voltages. Regardless of reasoning for lower
voltage input levels, a disparity exists in that a
considerable amount of signals do not lie within the bounds of the
ATxmega128A1U’s default analog input level(s).
The Epiphany DIY, in an effort to reduce external circuitry size and complexity, has built in pre-amplifier
circuits for all port “A” pins. The pre-amplifier circuits essentially remap the range of the ADC from the
internally reference range of 0 - 2.0625V to a more flexible 0 – 5V. The pre-amplifier circuits are
designed to work with the internal ADC voltage reference (VREF) of VCC/1.6V (2.0625V when
VCC=3.3V).
Configuring the Epiphany for 5V Analog Signals
The analog front end of the Epiphany DIY in order to achieve 5V level inputs requires a 5V regulated
power input to the system. There are two methods for inputting a regulated 5V signal into the Epiphany.
1) Purchase the Servo + package, and take advantage of the included 5V regulator. This regulator
automatically will generate the 5V power signal required for 5V analog signal readings.
2) Apply a regulated 5V power rail to the Epiphany DIY directly to the 5V power, screw terminal
(Figure ?) .
Analog Input Voltage Level Selection
Though the Epiphany DIY’s 8 special analog inputs are scaled appropriately for 5V signal levels, the full
range of the signal is limited by the input level selection dictated by the solder jumper in Figure ?. If a
5V power rail exists, the user may short the center and 5V side of the jumper, therefore enabling 5V
analog inputs to be read into the Epiphany. Otherwise, the default configuration, 3.3V must be used.
This is achieved by shorting the center pad, and the pad on the side labeled 3.3V. The user should
NEVER short all three pads of the jumper together since this could result in irreparable damage to the
Epiphany DIY. A final note, failing to short the center pad of the jumper to either 5V or 3.3V will inhibit
analog inputs to all the pins on port A. An available voltage source must be selected.
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Character LCD Port
The Epiphany DIY comes with a dedicated port for a
character LCD. The LCD port includes power inputs
as well as the LCD contrast, controlled by the
potentiometer displayed in figure ?. The LCD port at
the circuit level is simply made of Xmega i/o signal
lines duplicated from the GPIO header. The power of
the LCD header comes from the code base within the
Epiphany Software.
Table 1 LCD Pinout
Data 4 Enable
Data 5 Read/Write
Data 6 Register
Select Data 7 Contrast
+ 3.3 V + 3.3 V
GND GND
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USB Serial Port
The Epiphany DIY comes standard with a USB Serial
Port (Figure ?). This feature serves many purposes
including but not limited to programming, debugging,
interface to PC based programs
Programming Via the USB Bootloader
The Epiphany DIY ships with a bootloader program allowing for hardware programmer free flashing of
the onboard processor. To elaborate, this means that the Epiphany Is programmed by uploading compiled
code over a simple USB connection. Ordinarily
programming would include the use of a hardware
programmer, which is a device dedicated to uploading
compiled code to processors such as the one on the
Epiphany DIY.
In order to disable/enable the bootloader functionality
of the Epiphany DIY the bootloader enable jumper
displayed in figure ?, must be configured correctly.
Figure 1 USB-Boot Jumper
To enable the bootloader on the Epiphany the jumper must be closed (soldered)
To disable the bootloader auto reset on the Epiphany the jumper must be opened (unsoldered)
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XBee Wireless Adapter
The Epiphany DIY has an XBee radio socket located
on the underside of the board (figure ?). A XBee
radio is a wireless complement to the USB serial port.
The code interface for both modules is identical.
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Add-On Package Features
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DC Motor Packages
The Epiphany DIY robotics platform is so
deemed because of the capabilities to control,
and drive actuators in addition to the on board
processing, sensing etc. The Epiphany DIY
motor drivers are feature rich highly
configurable, and easy to use. The Epiphany
DIY software framework includes drivers to
control motors with only a few lines of code.
The drivers were even configured to drive at frequencies far above 20 kHz to eliminate audible switching
noise that could annoy the user.
Built In Thermal and Current Protection
The motor drivers selected for the Epiphany DIY are highly featuring rich. They not only drive motors
with a fair amount of current and voltage, the drivers are also very robust. The drivers (L6205s) have
over current and over heat safety. What this means is that in the event the motor diver(s) hit a peak
temperature or current beyond their intended use, they shut down automatically to prevent damaging
themselves.
High and Standard Power Configurations
The Epiphany motor drivers by default offer a current capability of ~3Amps continuously with peaks
upwards of ~6Amps (for further detail Motor Driver Electrical Specifications). However in applications
where more current is needed, the motor drivers are configurable to output double current, while still
making use of all the internal protections such as over heat and over current shutdowns. The only cost is
the number of motors drivable. The Epiphany DIY can support up to 2 motors with high power output or
up to 4 with standard power output.
Dual
The Epiphany Motor Driver Dual package includes all the circuitry in order to drive up to 2 DC motors
with standard power, or 1 DC motor with high power output.
Quad
The Motor Driver Quad package includes all the circuitry in order to drive up to 4 DC motors with
standard power, or up to 2 DC motor with high power output.
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Servo Packages
The Epiphany DIY has the capability to control
and self power up to 24 hobby servos by using a
dedicated on board servo controller. All of the
major processing of the servo control is handled
by a supplementary processor, both eliminating
high i/o usage on the Xmega, as well as
processing time. The Servo interface only
utilizes 2 pins from the Xmega,
Servo Safe Timeout Function
The ATtiny processor responsible for servo control has a built in timeout function. If a control signal
message is not received every half second or less the ATtiny will display a communication error, while
also releasing servos (servos are unpowered and allowed to relax). The communication error is displayed
by a rapid and erratically blinking led seen in figure ?. The timeout function is designed specifically to
prevent damage to servos if a program hang in the Xmega occurs. Likewise when debugging the servo
interface it is easy to tell when communication errors exist, when the respective led begins to blink
erratically.
Servo Package
The Servo Package for the Epiphany DIY is a basic package, that only includes the capability to control
servos. Powering the servos requires a 5V input into the respective screw terminals seen in figure ?.
Servo + Package
The Servo Plus Package has all the capabilities of the Servo package with the addition of a 16A 5V
regulator that pulls its input power form the Epiphany’s main power input.
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Getting Started
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Basic Connections
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Basic Power Connections
Figure 2 Color Key
Color Signal
Yellow Vin 8.4-14 V
Green Gnd
Red 5V
Purple ADC 3.3V/5V*
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Programming the Epiphany DIY
Bootloader Programming
The Epiphany DIY comes preloaded with a bootloader for programming, removing the need for a
hardware programmer,. The bootloader utility program can be found here. This utility uses the Epiphany
USB connection to upload compiled code (hex file). The bootloader works at any baud rate though
115200 is recommended
JTAG/PDI Programming
The Epiphany DIY can be programmed and debugged using a hardware programmer via the PDI or JTAG
connections found on the board. Utilizing these protocols will require the use of Atmel Studio
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Appendix
Glossary
ADC – Short for Analog to Digital Converter. An ADC in the most basic sense takes in an analog signal,
and outputs a number linearly interpolated from the resolution of the ADC and its respective VREF.
Atmel – Manufacturer of AVR microcontrollers such as the Xmega line that the uTinkerer is based upon.
DAC – Short for Digital to Analog Converter. A DAC is the complete opposite of and ADC. A number
is sent to the DAC, which then generates a voltage in accordance with the input resolution and voltage
range of the device.
Datasheet – Document that describes the functionality of a device. In electronics all circuit board
components even resistors have their own respective datasheet(s).
Debug – Or debugging in the context of this document, refers to the use of an interface tool such as the
AVR Dragon to peer into the inner workings of the microcontroller. This is done at a line per line basis in
the user’s code, or though running to a breakpoint placed by the user. Debugging the processor allows the
user to see register settings, memory location values etc. at any given instant. Debugging is nearly
identical to simulating, except that a simulator does not run on the application hardware. Simulators
depend on a software model of the processor architecture, and have no inherent knowledge of the
processor’s interaction with additional hardware. All peripheral interactions viewed in a simulator stem
from direct manipulation of the programmer. Real time hardware interaction versus user insertion is the
defining difference between debugging and simulation.
EBI – Short for External Bus Interface. This is a specific peripheral name unique to Atmel. The EBI
peripheral exposes the processor’s data and address buses. Through the exposure of the data and address
buses the microcontroller can be interfaced directly to external hardware.
IC = Short for integrated circuit.
MCU – Short for Micro Controller Unit
Microcontroller – a microprocessor that includes on-chip memory mapped peripherals.
PCB – Stands for Printed Circuit Board.
Peripheral – in the context of this document peripheral refers to an external or internal memory mapped
system or device.
Power rails – Positive and negative/neutral power signals for any given power voltage level.
Pre-Amplifier – An amplifier used to condition a signal prior to its desired application.
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Secure Digital Card – Also referred to as an SD Card. A type of non volatile (retains configuration after
power is removed) mass storage memory device.
Short Circuit - A low resistance connection between two signals, generally power rail signals. Shorts
between power rail signals cause the power supply to output large currents. Shorts often result in
irreversible damage to electronic devices.
VCP – Stands for Virtual Serial Port. A VCP is a specific USB protocol device that functionally mimics
a hardware serial port device.
Video encoder – A video encoder takes in video component signals and encodes them to a signal video
signal. In the context of the uTinkerer, the video encoder takes in RGB color components, and then
outputs a single video signal of the NTSC standard.
VREF – Short for voltage reference. This is a widely used acronym, but in the context of this document
it specifically refers to the voltage referenced of an ADC. The reference is generally the highest level
signal an ADC can convert. By setting the ADC VREF you therefore set the acceptable input range of the
ADC.
XBee – A standard of wireless radio interface devices produced by Digi International.
Xmega – A microcontroller line developed my Atmel. The uTinkerer is based on the ATxmega128A1U.
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Electrical Specifications
Table 2 Basic Unit Electrical Specifications
Item Minimum Typical Maximum Unit
Input Voltage* 8.4 12.0 14.0 V
PORT A inputs 0.0 5 V
Xmega input levels 0.0 3.3 3.6 V
i/o current -25 25 mA
3.3V Current Output 1500 mA
5V terminal input voltage** 5.0 5.5 V
Base current consumption** 30 mA
*If the Servo + regulator is not attached to the Epiphany DIY the minimum input is 7V and the maximum is 36V **Assumes that the Servo + regulator is not present on the Epiphany DIY.
Table 3 Motor Driver Electrical Specifications
Item Minimum Typical Maximum Unit
Low Power Motor Configuration
Peak current 5.6 A
Continuous Current 2.8 A
High Power Motor Configuration
Peak Current 11.2 A
Continuous Current 5.6 A
Input voltage 8 50 V
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Table 4 Servo Controller Electrical Specifications
Item Minimum Typical Maximum Unit
Servo Input Power* 5.00 5.50 V
Servo Reg Power** 4.83 4.95 5.08 V
Servo Signals 3.30 V
Signal Precision 3 µS
Signal Accuracy 5 µS
Angle Accuracy* ~.5 º
*User supplied input voltage. Needed if the Epiphany DIY does not have a Servo + regulator. **The voltage output range of the Servo + regulator
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Device List and Related Documentation