Looking for a simpler way to do floating point math and analog I/O? Check out our new PAK-XII!

What is 10 divided by 3? Your Basic Stamp thinks the answer is 3! Most other microcontrollers can't do any better because they all use integer math. Sometimes you can get by with integer math, but sometimes you need precision floating point results. That's where the PAK-I can help.

AWC is pleased to introduce the first of its Stamp Pak series of coprocessors: the PAK-I Math Coprocessor. This easy to use chip augments your Stamp or other microcontroller with full 32-bit floating point math. The PAK-I is a standard 18-pin IC that can interface with your microcontroller using only 2 pins (the PAK-II is a 28-pin .3" package).

Features include:

  • Robust, speed-independent serial interface -- only 2 pins required
  • Can connect multiple Stamp Paks to the same 2 pins using an enable pin for each device
  • Can work with IEEE754 format numbers (same format used by the PC)
  • Stamp II users can use ShiftIn and ShiftOut
  • Built-in function for converting floating point to ASCII
  • Synchronous operation -- read results when you are ready for them. No blocking and no interrupts required.
  • Fast 20MHz operation speed (ceramic resonator included) Worst case add time is about 55uS. Worst case divide is about 190uS. New! Both PAK-I and PAK-II operate at 20MHz.
  • Bonus 8 I/O pins you can control (if you only use 2 pins to talk to the PAK-I it is like getting 6 free I/O pins)
    PAK II: 16 Pins!
  • PAK II adds support for roots, exponentiation, sine, cosine, tangent, common and natural logarithms, and antilogs.

    The Details

    With the PAK-I you'll receive the IC, a ceramic resonator, a manual, and a software disk. The disk contains examples, and a program to convert between decimal numbers to the Pak-I and IEEE754 formats. The manual explains the communications protocol in detail, the connections required to the chip, and the commands you can use.

    Read the manuals online in pdf format: PAK-I or PAK-II. You can also read some technical notes and example applications in the Document Library.

    The PAK-II has the same great features, but includes: 16 I/O pins, log, ln, 10**x, e**x, sin, cos, tan, sqrt, x**y, and root functions. You can store 24 temporary results. Code is compatible with the PAK-I.

  • The PAK-II now includes the powerful POLY command. With this command, you can store a set of coefficients in the PAKs registers and then issue a single command to compute a polynomial with those coefficients.

    For example, suppose you need to compute 5X-3 (this is the classic y=mX+b equation). You could load register 1 with 5 and register 2 with -3 (using the STO command). Then simply execute the POLY command to computer X=5X-3.

    Suppose you wanted to compute .5X**3 + 3X**2 - 6.1X + .33 -- then you could store .5, 3, 6.1, and .33 in any four consecutive registers and issue a POLY command to make the required calculations. The PAK-II can automatically compute polynomials up to order 8 using this command.

    The PAK-I is in a standard 18-pin DIP package. The PAK-II is a 28-pin .3" package. Although the PAKs are especially easy to use with the Stamp, you can use them with any microcontroller. Here's some example code for the PIC and the Ubicom SX.

  • The new PAK-IX combines a PAK-II (with 8 digital I/O) and a 5 channel 10-bit A/D converter. The PAK-IX replaces one of the PAK-II's 8-bit digital ports with a 5 channel, 10-bit A/D converter. Use 0-5V references, or use one or two of the channels as references. In addition, the PAK-IX can store its data registers in EEPROM so you can set coefficients and forget them. You can find more information on this new chip on the PAK-IX page.

    Get it Now!

    Try a PAK-I or PAK-II for 21 days. If you aren't delighted, just send it back undamaged for a full refund of your purchase price. But once you see your Stamp handling real numbers, you won't want to be without it.

    Need volume pricing?


    Add to Cart PAK-I Coprocessor $23.49 each

    Add to Cart PAK-II Coprocessor (28 pin DIP w/resonator) $29.99 each

    Add to Cart PAK-II Coprocessor (Surface mount SOIC package w/through hole resonator) $32.95 each

    Add to Cart PAK-IX Coprocessor (28 pin DIP w/resonator) $32.95 each

    Add to Cart PAK-IX Coprocessor (Surface mount SOIC package w/through hole resonator) $34.95 each

    Notice: Basic Stamps are a product of Parallax Inc. AWC is in no way affiliated with Parallax.

Key Benefits

  • Saves your development time

  • Consumes very few processor resources

  • Handles 32-bit floating point numbers

  • Adds extra digital I/O

    Key Links

  • Guide to choosing a math coprocessor
  • Manual (PAK-I)
  • Manual (PAK-II)
  • paklib.htm - Using the PAK-I, II, or IX library
  • pak1bas.htm - A simple PAK-I, II, or IX program
  • paktemp.htm - Temperature measurement with a thermistor and a PAK-I
  • pak1java.htm - Use the PAK-I with a Parallax Javelin Stamp
  • pakif.htm - Interfacing other processors to the PAK protocol (including Microchip PIC and Ubicom SX code)
  • picbasic.htm - Using PAKs with PIC Basic (from MELabs)
  • avr.htm - Using a PAK with an Atmel AVR
  • pakhc11.htm - Using a PAK with a Motorola 68HC11
  • pak8051.htm - Interface to an 89C52 (an 8051/8052-compatibile processor)


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