Is STAMP what I need

ScottM

I have an idea for a project and I'd like some opinions on whether or not the STAMP can do what I need. I need to be able to do the following;

- drive a LED clock display
- use a numeric keypad for data entry
- drive two lamps
- drive a buzzer
- have a few switch inputs

I want to enter a number, then press a button to start the clock to countdown from that number of minutes and then light lamps at certain intervals.

How would the STAMP drive the clock display? There aren't enough I/O lines to directly drive the LED segments so either it has something better or I could find a display controller that would get its input from the STAMP.

Can the STAMP interface with a small keyboard or should I use a chip that decodes the keyboard matrix first?

Anyways, I'm thinking on building my project with the STAMP if I can.

Ravenkallen

The Stamp should be able to do it. Do you have any previous programming experience? For a project that uses a lot of I/O pins you might want to use the 40 pin Stamp(BS2p40)

Drive a LED clock display...

I would probably use a back lit serial LCD. The interface is so easy and it only uses one wire.


Use a numeric keypad for data entry...

It depends upon what kind of keypad you want to use. Some have a ton of pins. If you are going to use a 40 pin stamp then you should be fine...Check out this one..

http://www.sparkfun.com/commerce/product_info.php?products_id=8653


Drive two lamps...

What kind of lamps? Do you mean LEDs or small dc bulbs?

Drive a buzzer....

No problem. Depending on the buzzer, you might need to a transistor. A Stamp can only output so much current...Or maybe you meant a piezo speaker. These are more flexible in some cases...

have a few switch inputs....

No biggie....

The Stamp is an excellent Microcontroller to start off with. It is very friendly to the beginner. They assume that you have no programming or electronics experience..

Mike Green

A Stamp can do what you want although you'll need some kind of driver transistors for the LEDs, the two lamps, and the buzzer. The Stamp can scan the keypad as well. There's no built-in real time clock, but the Stamp can keep fairly accurate time over the kind of timeframe you're talking about by using PAUSE statements and controlling the execution time of the main loop.

I'd suggest using a BS2p40 which has two sets of 16 I/O pins. A 16 key keypad (for 4 x 4 keys) would need 8 pins (4 + 4 for scanning). A 4 digit 7 segment display with decimal points would need 12 pins (4 digit lines and 8 segment lines). Two lamps and a buzzer would use 3 more pins for a total of 23. That leaves plenty for "a few switch inputs". You'd need 8 segment transistors and 4 digit transistors, probably NPN for the segment drivers and PNP for the digit drivers. The lamps and buzzer would need driver transistors as well.

If you want the smaller (24-pin) Stamp package, you could use a 74HC595 as an output I/O expander plus a ULN2803 for the segment drivers. That would need only 4 I/O pins. You could also use an external keypad scanner like the 74C922 (look here) which would need only 5 I/O pins. You could cascade another 74HC595 and ULN2803 for the two lamps and the buzzer and have 5 other high power outputs available for a total of 4 (74HC595s) + 4 (digit drivers) + 5 (74C922) + "a few switch inputs" (up to 3).

ScottM

Thanks for the ideas. I graduated as electronic technologist many years ago and I program in VB6 and lately C#. A long time ago, I used to program in 6502 assembler. More recently I used controllers in robotic test equipment. Not having used a stamp before, I thought I would post here first. Good choice. The first task is to figure out how to use the keypad to enter a time, say two minutes, and have the clock display start counting down from that time.