# Pin Descriptions

## BASIC Stamp 1

| Pin | Name | Description
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).

## BASIC Stamp 2

| Pin | Name | Description
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 sink 25 mA and source 20 mA. However, the total of all pins should not exceed 50 mA (sink) and 40 mA (source) if using the internal 5-volt regulator. The total per 8-pin groups (P0 – P7 or P8 – 15) should not exceed 50 mA (sink) and 40 mA (source) 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 - 15 VDC (6-40 VDC on BS2-IC Rev. e, f, and g), which is then internally regulated to 5 volts. Must be left unconnected if 5 volts is applied to the VDD (+5V) pin.

## BASIC Stamp 2e, 2sx, 2p, 2pe, 2px

| Pin | Name | Description
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.

## BASIC Stamp 2p40

| Pin | Name | Description
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.

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BASIC Stamp Help Version 2.5.4

Copyright © Parallax Inc.

8/8/2012