Basic stamp homework board manual
Parallax, Inc. • BASIC Stamp HomeWork Board ver 1.1 Page 4
Figure 2
BASIC Stamp
HomeWork Board
Schematic
VIN
1
VSS
VOUT
VR1 LM2936
PB1
Reset
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
X4
1
2
3
4
5
6
7
8
9
10
11
12
13
X3
Breadboard
Vin
+
C1
10
µF
20 MHz
10k
Ω
10k
Ω
1/2 UM11TN
DTA114EETL
24LC16B
U2
Dat
Clk
N/C
Vdd
Vss
P0
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
P15
Vdd Vdd
Vdd
Vdd
Vdd
Vin
RN1-3
4.7k
Ω
RN1-4
4.7k
Ω
RN1-2
4.7k
Ω
R1
10k
Ω
9V Transistor
Battery
Vss
Vss
Vss
Vss
Vss
P8
P9
P10
P11
P12
P13
P14
P15
P5
P6
P7
15
16
17
18
19
20
21
22
23
24
25
28
27
26
J2
DB9 Female
C4
0.1
µF
C3
0.1
µF
PowerLED
D2
10k
Ω
10k
Ω
1/2 UM11TN
10k
Ω
10k
Ω
A0
A1
A2
Vdd
P0
P1
P2
P3
P4
Vdd
RN1-1
4.7k
Ω
R2
100
Ω
RA0
5
RA1
6
RA2
7
RA3
8
RB0
9
RB1
10
RB2
11
RB3
12
RB4
13
VSS
1
VSS
14
RTCCI
2
VDD
3
VDD
4
RB5
RB6
RB7
RC0
RC1
RC2
RC3
RC4
RC5
RC6
RC7
U1
PIC16C57-20/SS
(PBASIC2/SS)
1
6
2
7
3
8
4
9
5
Vss
Vss
Vss
Vss
OSC1
OSC2
2
3
RN2
22
0Ω
RN5
22
0Ω
RN4
22
0Ω
RN3
22
0Ω
Power Consumption and Battery Life
Parallax normally designs BASIC Stamp boards with power jacks for wall transformers. Wall transformers provide
plenty of power but they are not as portable for science fairs, robots and environmental datalogging. Considering
that the BASIC Stamp draws only small amounts of current it could be deployed in a remote location and run
from a battery for a long time.
The BASIC Stamp has commands for reduced power consumption, but what about the power indicator LED? It
could drain the battery in a day or two by itself if being used to indicate a power supply! LEDs consume current,
typically 10-12 mA. Removing the LED wasn’t an option since it discloses the common technical support problem
of a missing power supply.
The solution was to connect BASIC Stamp HomeWork Board’s power LED to the “clock” line of the BASIC
Stamp’s EEPROM. The EEPROM’s clock line is active only when the BASIC Stamp is actually running a
program. Moreover, the BASIC Stamp HomeWork Board’s power LED is a low current LED consuming only
about 2 mA.