Pin Descriptions

1

VIN

Unregulated power in: accepts 5.5 - 15 VDC (6-40 VDC on BS1‑IC rev. b), which is then internally regulated to 5 volts. May be left unconnected if 5 volts is applied to the VDD (+5V) pin.

2

VSS

System ground: connects to BS1 Serial Adapter ground for programming.

3

PCO

PC Out: 4800 baud serial output (TTL level) to PC.

4

PCI

PC In:  4800 baud serial input (TTL level) from PC.

5

VDD

5-volt DC input/output: (Also called +5V) if an unregulated voltage is applied to the VIN pin, then this pin will output 5 volts.  If no voltage is applied to the VIN pin, then a regulated voltage between 4.5V and 5.5V should be applied to this pin.

6

RES

Reset input/output: goes low when power supply is less than approximately 4.2 volts, causing the BASIC Stamp to reset.  Can be driven low to force a reset.  This pin is internally pulled high and may be left disconnected if not needed.  Do not drive high.

7-14

P0-P7

General-purpose I/O pins: each can sink 25 mA and source 20 mA. However, the total of all pins should not exceed 50 mA (sink) and 40 mA (source).

1

SOUT

Serial Out: connects to PC serial port RX pin (DB9 pin 2 / DB25 pin 3) for programming.

2

SIN

Serial In: connects to PC serial port TX pin (DB9 pin 3 / DB25 pin 2) for programming.

3

ATN

Attention: connects to PC serial port DTR pin (DB9 pin 4 / DB25 pin 20) for programming.

4

VSS

System ground: (same as pin 23), connects to PC serial port GND pin (DB9 pin 5 / DB25 pin 7) for programming.

5-20

P0-P15

General-purpose I/O pins: each can source and sink 30 mA. However, the total of all pins should not exceed 75 mA (source or sink) if using the internal 5-volt regulator.  The total per 8-pin groups P0 – P7 or P8 – 15 should not exceed 60 mA (source or sink) if using an external 5-volt regulator.

21

VDD

5-volt DC input/output: if an unregulated voltage is applied to the VIN pin, then this pin will output 5 volts.  If no voltage is applied to the VIN pin, then a regulated voltage between 4.5V and 5.5V should be applied to this pin.

22

RES

Reset input/output: goes low when power supply is less than approximately 4.2 volts, causing the BASIC Stamp to reset.  Can be driven low to force a reset.  This pin is internally pulled high and may be left disconnected if not needed.  Do not drive high.

23

VSS

System ground: (same as pin 4) connects to power supply’s ground (GND) terminal.

24

VIN

Unregulated power in: accepts 5.5 - 12 VDC (7.5 recommended), which is then internally regulated to 5 volts. Must be left unconnected if 5 volts is applied to the VDD (+5V) pin.

1

SOUT

Serial Out: connects to PC serial port RX pin (DB9 pin 2 / DB25 pin 3) for programming.

2

SIN

Serial In: connects to PC serial port TX pin (DB9 pin 3 / DB25 pin 2) for programming.

3

ATN

Attention: connects to PC serial port DTR pin (DB9 pin 4 / DB25 pin 20) for programming.

4

VSS

System ground: (same as pin 39) connects to PC serial port GND pin (DB9 pin 5 / DB25 pin 7) for programming.

5-20

P0-P15

General-purpose I/O pins: each can source and sink 30 mA. However, the total of all pins (including X0-X15) should not exceed 75 mA (source or sink) if using the internal 5-volt regulator.  The total per 8-pin groups (P0 – P7, P8 – 15, X0 – X7 or X8 – X15)  should not exceed 100 mA (source or sink) if using an external 5-volt regulator.

21-36

X0-X15

Auxiliary Bank of General-purpose I/O pins: each can source and sink 30 mA. However, the total of all pins (including P0 – P15) should not exceed 75 mA (source or sink) if using the internal 5-volt regulator.  The total per 8-pin groups (P0 – P7, P8 – 15, X0 – X7 or X8 – X15) should not exceed 60 mA (source or sink) if using an external 5-volt regulator.

37

VDD

5-volt DC input/output: if an unregulated voltage is applied to the VIN pin, then this pin will output 5 volts.  If no voltage is applied to the VIN pin, then a regulated voltage between 4.5V and 5.5V should be applied to this pin.

38

RES

Reset input/output: goes low when power supply is less than approximately 4.2 volts, causing the BASIC Stamp to reset.  Can be driven low to force a reset.  This pin is internally pulled high and may be left disconnected if not needed.  Do not drive high.

39

VSS

System ground: (same as pin 4) connects to power supply’s ground (GND) terminal.

40

VIN

Unregulated power in: accepts 5.5 - 12 VDC (7.5 recommended), which is then internally regulated to 5 volts. Must be left unconnected if 5 volts is applied to the VDD (+5V) pin.