Home Chapter 6 BS2 Pins and their functions
BS2 Pins and their functions

Discharge your hand to a metal object especially if you are wearing wool or nylon.

CAREFULLY remove the chip from the static sensitive foam watching not to bend any of the pins.

Place the Chip into the socket on the Board of Education with the 1/2 circle being toward the top and the large chip oriented at the bottom of the Board of EDU. Be careful not to bend any pins. Check to see if the chip is sitting cleanly into the socket and then use your thumb to push the chip down with about 2 pounds of pressure to get it to fit snugly. Check that all the pins are intact and that none are bent.


Basic Stamp 2 and board of EDU


Now, look at the chip and become familiar with each of the Pin Functions on the Basic Stamp 2. Notice how on the left hand side of the chip written on the board of EDU is the pin function in white.

Reading down the left row pin 1, 2, 3, etc.


Pin outs of the BS2

 Chip enlarged

Pin 1 name is SOUT or Serial Out. This pin connects to the serial port of your PC for programming the stamp.

This pin is a serial communication line, meaning the information arrives and is sent out, one bit of information after another, in a row through a single wire.

Pin 2 is SIN serial, which connects to the serial port of your PC for programming.

Pin 3 ATN the attention pin connects to the serial port of the basic stamp.

Pin 4 is connected to VSS or System Ground.

Pin 5–20 are (I/O) are general-purpose input output pins. In other words you can redefine if the pins are used as inputs or as outputs, which is powerful and flexible.

Each pin can sink (accept as input) 25 MA and can source (provide as output) 20 MA but pins 0-7 and 8-16 can source a max of 50 mA at one time. This is important and will be revisited later in this book.

Notice how on the Board of EDU that the pin outs are also connected via electrical traces under the board near the white prototyping area.

Pin 21 is VDD or 5 volts.


Watch the Green LED. If you ever see the green LED flicker or dim on board of the circuit then you are pulling too much amperage or voltage from the stamp.


Keep in mind that the power regulator can only convert so much amperage and voltage and you must have enough for the stamp as well.

Pin 22 RES reset switch. Functions as a systems reset starting your software from the start of the program. This pin should never be driven high.

Pin 23 VSS Ground is also connected to pin 4. All grounds should be common.

Pin 24 Vin is unregulated power and can accept 5.5 to 15 volts input. This pin can be left unconnected if power is applied to pin VDD pin 21.