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Propeller Board of Education (#32900)
The form of the original Board of Education
©
meets the powerful function of the multicore Propeller
™
microcontroller. A built-in set of peripherals makes it ready to support an amazing array of projects,
prototypes, hands-on activities, and kits. The Propeller Board of Education is ideal for learning the basics
of electronics, programming and robotics. It also simplifies advanced applications that require RF-linked
communication, audio/visual peripherals, and gigabytes of SD memory.
Features
Built-in Propeller microcontroller, 64 KB
EEPROM and 5 MHz crystal oscillator.
Breadboard, sockets for power and I/O
access, and six servo ports with power-
select jumpers for easy prototyping
Automatically selects between USB and
external power sources and provides
USB over-current protection
9 V battery and center-positive 2.1 mm
power connectors offer two external
power options
Convenient reset button and 3-position
power switch
Onboard mini stereo-audio jack, electret
microphone, and VGA port for
audio/visual projects
Built-in microSD card and XBee wireless
module sockets simplify advanced
applications
Dedicated analog header sockets
provide three 10-bit inputs and two
buffered variable-resolution outputs
2x20 header for connecting I/O pins to
VGA, XBee, Propeller clock and reset,
USB serial flow control, and up to 10
LEDs
Indicator lights for system power, servo
power, eight color-coded VGA channels,
two analog output levels, XBee Tx/Rx,
and USB Tx/Rx
SEPIC 5 V switching regulator can
deliver up to 3 A across the commercial
temperature range
Linear 3.3 V regulator can deliver up to
460 mA at room temperature
Key Specifications
Power requirements: 4–16 VDC
Communication: USB for programming
Dimensions: 4.375 x 3.05 x 0.625 in
(11.11 x 7.75 x 1.50 cm)
Operating temp range: +32 to +158 °F
(0 to +70 °C)
Application Ideas
Mount on a Boe-Bot
robot chassis to
create your own customizable Propeller
robot
©
Use in the classroom to teach
electronics, programming, robotics, and
the fundamentals of electronic product
design with a multicore microcontroller
Packing List
Propeller Board of Education PCB
Strip of 4 rubber feet
Jumper wires
Copyright © Parallax Inc.
Propeller Board of Education (#32900)
v1.0 3/15/2012 Page 1 of 9
Functional Description
(20) Status LEDs
VGA LEDs (active-high)
2 red, 2 green, 2 blue, 2 yellow (H & V sync)
XBee LEDs (active-low)
Active low: red (DI) and blue (DO)
(19)
Switching
Regulator
In: 4-16 VDC
Out: 5V, 3A
(18) 2x10 Socket Access—J5 Header
Signal + LED connections:
VGA R1, R0, G1, G0, B1, B0, H, V
XBee DO, DI
Signal only
XBee /RTS, ASOC, /CTS, /DTR, /SSI, /RST
Propeller XI, /RST
Serial over USB flow control (/CTS, /RTS)
(17) Servo Ports
6 ports (I/O pins P14..P19)
Jumper shunt left of each pair
sets supply voltage to 5 V or Vin
(1) External Power Inputs
9 V battery clip
2.1 mm center-positive jack
(2) Multicore Propeller
Microcontroller System
- Non volatile 64 KB EEPROM
- Propeller Microcontroller
- 3.3 V, 460 mA regulator
- 5.00 MHz crystal oscillator
(16) + Supply Sockets
3.3 V and 5 V
(15) Propeller I/O P0..P15
Socket access to P0..P15
(3) VGA Video
output port
(4) Electret Microphone
Sampled by Propeller using
sigma-delta analog to digital
conversion
(5) USB Port
- Load programs
- Serial over USB communication
- Debugging
- Power supply input (USB 2.0)
5 V, up to 450 mA
(14) Breadboard
34 rows of 5 sockets
in 2 columns
(13) GND, DA, AD Sockets
GND Sockets
Digital to Analog DA0, DA1
Analog to Digital AD0..AD3
(6) Stereo
Output
Jack, 1/8”
(7)
MicroSD
Socket
(8)
XBee
Digital RF
Module
Socket
(9) Power Switch
with green LED
indicator lights for
settings 1 & 2
0 – Off
1 – System on
2 – System +
servo on
(10)
Reset
Button
(12) Digital to Analog Lights
Yellow LEDs vary in
brightness with duty
modulated digital to analog
output voltage
(11) Analog to Digital
Converter
10 bit I2C analog to
digital converter
(a) Labeled
power pads
(b) SOIC IC
land pattern
(c) Outer pads alternate
between I/O pin and SOIC
and MSOP pad connections
(d) Labeled
ground pads
(b) MSOP IC
land pattern
(21) Surface-mount
Pads (Rev A only)
(23) Rubber Foot Outline
(24) Product Resource Page
(22) XBee, MicroSD
Aux Access (Rev A only)
Copyright © Parallax Inc.
Propeller Board of Education (#32900)
v1.0 3/15/2012 Page 2 of 9
(1) External Power Inputs
The 9 V battery clip and 2.1 mm center-positive jack are two of the Propeller BOE’s three power input
options. The board will accept 4 VDC to 16 VDC from either of these inputs. These input ports are
useful for robots and other remote applications where the application continues to run when it’s not
connected to, and drawing power from, its USB programming port (the third option, see (5)).
(2) Multicore Propeller Microcontroller System
64 KB I2C EEPROM for non-volatile program and data storage.
8 core Propeller microcontroller
3.3 V, 460 mA voltage regulator
5.00 MHz crystal oscillator
The Propeller provides the EEPROM’s I2C clock through I/O pin P28, and communicates with its I2C data
line through I/O pin P29. The Propeller microcontroller can multiply the 5.0 MHz crystal oscillator signal
by up to 16 for a system clock frequency of 80 MHz.
(3) VGA Video Output Port
This is a convenient port for Propeller microcontroller applications that display data and graphics on
devices with VGA inputs, such as certain computer monitors and televisions. Signals are applied to the
VGA driver circuits by running jumper wires from Propeller I/O pin sockets (15) to VGA inputs on the
2x10 socket (18).
(4) Electret Microphone
This microphone is connected to Propeller I/O pins 20 and 21 through a sigma-delta circuit (a low-pass
RC filter with negative feedback).. Propeller applications can use the RC circuit to measure the
microphone’s voltage output with sigma analog to digital conversion. This is useful for basic sound
recording and analysis.
(5) USB Port
In addition to loading programs from the PC into the Propeller microcontroller, the USB port can also be
used for serial over USB communication with a terminal, as a conduit for debugging software, and as a
5 V power input. For power, the USB Port is input current limited to between 450 mA and 500 mA. This
prevents any unexpected responses from USB 2.0 ports to current draws from motors, wiring mistakes,
etc.
(6) Stereo Output Jack
This 1/8” jack is useful for speech synthesis, music, and other audio applications. I/O pins P26 (right
channel) and P27 (left channel) are hardwired to the low-pass filter, amplifier and coupling capacitor
circuits that can drive headphones, ear-buds, speakers with built-in amplifiers, or line level inputs.
(7) MicroSD Socket
This socket is useful for applications that use a microSD card. With common sizes of 1 to 32 GB, these
cards are great for applications where there is more data than can conveniently be stored in the Propeller
chip’s 32 KB of RAM or the board’s 64 KB EEPROM. Examples include:
Extended memory model (XMM) C language programs
Multiple Spin program application images that can be boot-loaded
Large lookup tables
Record and playback of audio files
Datalogging
This socket is hardwired to I/O pins: P22 - DO (data out); P23 - CLK (clock); P24 - DI/CD (data in and
card detect); P25 - /CS (active low chip select).
Copyright © Parallax Inc.
Propeller Board of Education (#32900)
v1.0 3/15/2012 Page 3 of 9
(8) XBee Digital RF Module Socket
This socket accommodates most XBee wireless modules and is useful for applications where the Propeller
Board of Education is part of an XBee wireless network. Possible applications include robot team sports,
remote data logging, and wireless message exchange with computer that has an XBee connected (XBee
module + adapter or compatible USB XStick).
NOTE: This socket does not support XBee Wi-Fi.
(9) Power Switch
This 3-position switch can select between system power off (position-0), system power on (position-1),
and system power + servo power on (position-2); see Servo Ports (17) for more details.
(10) Reset Button
Provides a mechanical means of restarting the Propeller microcontroller’s program. Press and hold to
keep the microcontroller in reset, press and release to reset and allow the Propeller to load the program
in EEPROM.
(11) Digital to Analog Converter
Propeller applications can use this 10-bit analog to digital converter (ADC) to monitor analog inputs
labeled A0, A1, A2, and A3 on (13). This ADC was chosen because it can share the I2C bus with the
board’s 64 KB external EEPROM memory, which keeps more I/O pins available for general purpose use.
With a 400 kHz clock (Fast I2C), it supports sampling rates up to 25 kHz and supports common low
bandwidth measurements like DC and 3 phase signals. This ADC has a 5.0 V reference, so it reports
voltage measurements in units of 1024ths of 5 V.
(12) Digital to Analog Indicator Lights
Yellow LEDs vary in brightness with duty modulated digital to analog signals. These lights are primarily a
visual indicator of the output voltage at DA sockets (13), but they also indicate stereo output jack (6)
signal activity.
(13) GND, DA, AD Sockets
GND Sockets – common ground for the system
Digital to Analog DA0, DA1
o
Output voltage range: 0 to 3.3 V
o
DA0 is the digital to analog voltage from P26 after it has passed through a low-pass filter
and buffer amplifier (but before it has passed through the coupling capacitor to the
stereo output jack’s right speaker channel).
o
DA1 is the same as DA0, but the duty modulated signal is provided by P27.
Analog to Digital AD0..AD3
o
Input voltage range: 0 to 5 V
(14) Breadboard
Solderless breadboard with 0.1” pin spacing for circuit prototyping. This breadboard has 34 5-socket
rows arranged in 2 columns. The columns are separated by a valley in the middle.
(15) Propeller I/O P0..P15
Socket access to P0..P15, conveniently located to the left of the breadboard (14) and close to the 2x10
socket header (18). Jumper wires can be used to connect these I/O pins to circuits on the breadboard,
or to the 2x10 socket header’s VGA, XBee, Propeller, and serial over USB features.
(16) + Supply Sockets
The positive 3.3 V and 5 V supply sockets are positioned along the top of the breadboard, making it
convenient to jumper supply voltage to circuits built onto the breadboard.
Copyright © Parallax Inc.
Propeller Board of Education (#32900)
v1.0 3/15/2012 Page 4 of 9
(17) Servo Ports
These ports are convenient for connecting servos and other peripherals, such as the PING))) Ultrasonic
Distance Sensor and Parallax Serial LCD. Each servo port has a label printed above it indicating which
I/O pin will communicate with the peripheral. Labels indicating the GND (ground), PWR (power) and SIG
(signal) pins for each port are along the right.
Each pair of servo ports has power selection pins with a jumper shunt to its immediate left. Each pair of
ports can be set to 5 V by placing the jumper over the pair of pins closer to the 5V label, or to
unregulated input voltage from the external power inputs by placing it over the pair of pins closer to the
VIN label.
When the jumper for a given pair of ports is set to 5 V, that pair of ports will receive regulated 5 V power
whenever the Power Switch (9) is set to 2. If the jumper for a pair of servo ports is set to VIN, that pair
of servo ports will receive power so long as a power source is connected to either the 9 V battery clip or
the 2.1 mm barrel jack and the power switch is set to 2.
(18) 2x10 Socket Access—J5 Header
The J5 header is just to the left of the Propeller I/O P0..P15 header (14) making it convenient to connect
Propeller I/O pins to built-in LEDs, VGA, XBee, and serial-over-USB flow control signals, as well as certain
Propeller chip inputs. See the J5 Header table on page 8 for more information on each socket.
VGA Sockets
The VGA sockets are connected to active-high, color-coded LEDs and buffered inputs that drive the VGA
Video Output Port (3) channels. The inputs labeled R1 and R0 are red channel inputs and drive red
indicator LEDs. G1 and G0 are green inputs and have green indicator LEDs, and the B1 and B0 are blue
inputs and have blue indicator LEDs. The horizontal and vertical channel inputs are labeled H and V, and
have yellow indicator LEDs.
XBee Sockets
The XBee DO and DI sockets connect to DO and DI sockets on the XBee Digital RF Module Socket
headers (8). Signals applied to these sockets also drive active low LEDs. The DO socket LED is color-
coded blue, and the DI socket LED is color-coded red.
XBee sockets labeled /RTS, ASOC, /CTS, /DTR, /SSI, /RST are connected to sockets of the same name on
the XBee Digital RF Module Socket’s headers (8). As with all the sockets along the left side of the
J5 Header, they do not drive any LEDs. For more information on these signal lines and their functions,
download the XBee reference manual from
www.digi.com.
Propeller Sockets
Most of the socket labels have lines connecting them to categories like VGA, XBee, and Serial over USB
(next to the USB trident). There are two sockets, labeled /RST and XI, that do not have lines connecting
them to category labels. These provide connections to the Propeller chip’s active-low reset (/RST) and
external clock input (XI) pins. A low signal sent to the /RST line will hold the Propeller chip in reset state,
just like holding down the reset button, and releasing the input to high after a low signal allows the
program to load from EEPROM. The Propeller will also drive this signal low if a brown-out condition is
detected. The XI input is for applications that need to make use of a clock signal other than the Propeller
chip’s internal oscillator or the Propeller Board of Education’s 5 MHz crystal oscillator. This socket makes
it convenient to supply the Propeller chip with a clock signal from an external source with an active
output for any application that might require a custom system clock frequency.
Serial over USB Sockets
Propeller I/O pin P30 is connected to the PC’s Rx input signal, and P31 is connected to the PC’s Tx output
signal for asynchronous serial communication without flow control. For flow control, simply run jumper
Copyright © Parallax Inc.
Propeller Board of Education (#32900)
v1.0 3/15/2012 Page 5 of 9
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