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PropStick USB (#32210)
P8X32A Module with USB Programming Port
The PropStick USB is a complete Propeller development tool with a convenient built-in USB programming
interface. The PropStick USB module comes fully assembled, with a USB A to Mini-B Retractable Cable
(#805-00010). The PropStick USB is suitable for all new Propeller-based designs. PropStick USB
mounting possibilities include breadboard, perfboard with wire-wrap, or in a 600 mil 40-pin socket
soldered to a PCB.
Features
P8X32A-M44 8-cog multiprocessing
microcontroller
32 KB EEPROM
3.3 V regulator with power and
ground connections
5.00 MHz removable crystal oscillator
Reset button
FTDI 232R USB interface with red and
blue LEDs for transmit/receive activity
600-mil wide 40-pin DIP package,
modeled after the P8X32A-D40
USB A to Mini-B Retractable Cable
included
Pin-1
indicator
Reset button
32 KB EEPROM
program and
data storage
Propeller
P8X32A-M44
microcontroller
Socket with 5.00
MHz crystal
oscillator
3.3 V voltage
regulator
USB to serial
circuit
Key Specifications
Power requirements: regulated
5-9 VDC. (See Current Consumption
and Availability below)
Communication: 232R USB interface
to PC for programming and
bidirectional communication
Operating temp: 0 to 70 °C
(32 to 158 °F)
Dimensions: 2.0 x 0.6 x 0.45 in
(51 x 16 x 12 mm)
Serial receive
indicator LED
Serial transmit
indicator LED
USB Mini B port for program
downloads, PC/Propeller
communication and debugging
USB VCP Drivers Required
The PropStick USB requires FTDI USB drivers. These drivers for Windows 2K/XP/Vista are installed
automatically with the Propeller Tool Software available from the Downloads link at
www.parallax.com/Propeller.
To install these drivers separately, click on the USB Drivers link at the
bottom of the home page at www.parallax.com and follow the USB Driver installation steps as shown
there. That page provides a link to troubleshooting instructions if needed.
Copyright © Parallax Inc.
PropStick USB (#32210)
v1.2 1/27/2009 Page 1 of 4
Current Consumption and Availability
The PropStick USB contains an on-board 3.3 V voltage regulator. Depending on the voltage input into
the PropStick USB and the ambient temperature, the maximum current available to power your Propeller
chip and application circuits will vary. For example, assuming a room temperature of 80 °F (26.7 °C),
your maximum available current with a 5 VDC supply is 280 mA. At 9 VDC, the available current drops to
84 mA. For information about the Propeller chip’s current consumption under different operating
scenarios, refer to the Propeller Datasheet (available from the Downloads link at
www.parallax.com/propeller).
Calculation of Maximum Current Draw
According to the National Semiconductor’s LM2937 datasheet (available from www.national.com), the
maximum allowable junction to ambient thermal resistance (θ
JA
) for the SOT-223 package used on the
PropStick USB is 174
°C/W.
This quantity can be described in terms of the maximum allowable
temperature rise (T
R(max)
) and the power dissipated (P
D
) as:
θ
JA
=
T
R
(max)
P
D
o
≤
174
C
W
…where T
R(max)
is the difference between the maximum junction temperature T
J(max)
, which is fixed at
125
°C
for the LM2937IMP-3.3, and the maximum ambient temperature T
A(max)
, which varies depending
on your local environment:
T
R
(max)
=
T
J
(max)
−
T
A
(max)
=
125
o
C
−
T
A
(max)
P
D
is also related to the input voltage (V
IN
), output voltage (V
OUT
), load current (I
L
), and quiescent current
(I
G
) by:
P
D
=
(
V
IN
−
V
OUT
)
•
I
L
+
(
V
IN
)
•
I
G
For the PropStick USB, V
IN
= Your Input Voltage, V
OUT
= 3.3 V, T
A(max)
= Operating Temperature (26.7°C
for room temperature), and from the datasheet, I
G
will not exceed 10 mA. You can solve for your load
current in terms of the other variables and constants using the following formula:
T
J
(max)
−
T
A
(max)
I
L
≤
θ
JA
V
IN
−
V
OUT
−
(
V
IN
)
•
I
G
The graph on the following page depicts how input voltage and ambient temperature affect the maximum
load current of the PropStick USB.
Copyright © Parallax Inc.
Product Name (#32210)
v1.2 1/27/2009 Page 2 of 4
Ambient Temperature vs. Maximum Load Current
450
400
Vin = 5 V
350
Maximum Load Current (mA)
300
250
200
Vin = 7.5 V
150
Vin = 9 V
100
50
0
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
Ambient Temperature (Degrees Celcius)
Schematic and Pin Map
The PropStick USB was closely modeled after the P8X32A-D40, the DIP format Propeller chip. There are
only three places where the PropStick USB varies from the P8X32A-D40 in pin assignments:
•
Pin 10 (BOEn) is tied to VSS, permanently enabling the brown-out detector.
•
Pin 12 (VIN) is the input to the onboard regulator and should be supplied with 5-9 VDC.
•
Pin 32 (VDD) is the output of the regulator and provides up to 280 mA of 3.3 VDC to power the
Propeller circuit and your projects (see Current Consumption and Availability above). Alternatively,
the on-board regulator may be bypassed by connecting an externally regulated 3.3 VDC to VDD.
NOTE:
The PropStick USB is
not
for use in 40-pin BASIC Stamp boards made by Parallax (as in the
Professional Development Board or BS2p40 Demo Board).
Copyright © Parallax Inc.
Product Name (#32210)
v1.2 1/27/2009 Page 3 of 4
Schematic (Rev D)
Copyright © Parallax Inc.
Product Name (#32210)
v1.2 1/27/2009 Page 4 of 4
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