THE
PUBLIC
SCHOOL
TELIC ARTS EXCHANGE

For those on the interest list who have taken this class and feel ready to go a step further with microprocessor circuits, a new 8-bit Lab workshop scheduled for August 23rd may be of interest: http://la.thepublicschool.org/class/1342

We'd also like to (pre-)announce a new membership program at The Public School that will allow students to take an unlimited number of classes with a $200 annual membership. For those of you who have taken a previous 8-bit Lab class (or other classes at TPS), we'd like to offer the opportunity to apply a credit from those classes towards the yearly fee. If you become a member, any future 8-bit lab classes are going to cost you $10 to cover the materials cost only. If you are interested in this membership offer, please email sean at telic.info

Thanks for your feedback Phil! AS1107PL is a great find. I'll definitely take your suggestions into account for any future classes..
: nP

Here are some comments regarding the materials covered in the class:

I'd recommend looking at the MAX7221 in lieu of the 7219 as the 7221 provides more serial compatibility with other chips. So if you're designing a circuit that will use SPI or Microwire Serial interface, you'll want to go with the MAX7221. (It's only a little bit more expensive). Also the MAX7221 provides better EMI specs, so if you're working with audio or other noise sensitive applications, use the MAX7221.

I also found the AS1107PL (by AUSTRIAMICROSYSTEMS ) which is a direct knock off of the MAX7221, but for about $6 bucks less per chip!!. ( AS1107PL = $3.88 ). It is compatible with the "LEDcontrol" library and works the same as the MAX7221. The AS1107PL actually has additional features, but you can't access those directly from the library. The LEDControl library is a more robust version of the Matrix library referenced in the class notes and is still in active development.

AS1107PL LED Matrix Chip (clone of MAX7221)
http://www.newark.com/jsp/search/productdetail.jsp?SKU=59P3692

LED Control Library:
http://www.arduino.cc/playground/Main/LedControl

I'd also add that a good chip for playing with higher power circuits is the ULN2803A which is a transistor array. (Darlington Array), which will allow you to sink a larger amount of power than can be sourced by the 74HC595 alone. Once you move beyond controlling one LED per channel, you'll probably need to move to something with transistors. Using the two together, allows you to power devices with much higher current requirements than just LEDs. Basically it's: Arudino -> 74HC595 -> UNL2803A -> higher voltage / higher power loads. Keep in mind that the 595 sources power (provides power) whereas the UNL2803 sinks power (routes power to ground). The advantage of the UNL2803A is that it's the same package format as the 595 and provides 8 transistor controls which match the 8 outputs of the 595.

Datasheet for ULN2803A (about $0.41 per unit):
Up to 30V and 500ma
http://www.st.com/stonline/products/literature/ds/1536/uln2803a.pdf

There are more powerful versions, but I've found it better to use small relays once I get above those limits. The last thing I built using a shift register pulled 60watts so I used the shift register and a transistor array to drive micro relays. (a shift register can not source enough power on it's own to drive relays).

Phil,

Still looking into this issue.. our Drupal guru is out the country, so it might have to wait a bit more ;) In the meantime, please post any comments regarding the class notes on this page.

thanks!
: nP

Nik,

The class notes don't seem to allow me to post a comment??

Class notes for the workshop are now up at: http://la.thepublicschool.org/class-notes/256

I'd like to make a few more additions, but the bulk of the material we covered in class (including the list of parts) is there. Post comments on the page if you'd like to see anything covered in more detail.. your feedback is always appreciated!

: nP

Hi, is this the area the class notes will post?

Also, Chandler, can you contact me. We talked briefly after class about somebody you know who was using wifi to triangulate and I'm interested in following up on this. There doesn't appear to be a 'private' message are of this site. You can contact me at philglau at gmail

The Public School will provide the electronics we'll use in the class. If you have your own Arduino board, you are welcome to bring it. Otherwise, it would be great if everyone can bring a laptop with the Arduino environment downloaded and installed (follow directions at http://arduino.cc/en/Main/Software).

If you have any interesting specimens of LEDs, modules or drivers, feel free to bring those for a show and tell as well!

what should we bring with us?

Just a reminder.. this class is taking place Saturday! Note that this is going to be our first 'intermediate' level electronics workshop, so it is a great follow-up for those who have taken the introductory 8-bit Lab or have a little bit of electronics experience. While the primary subject is LEDs, the class is as much about expanding the reach of your little microprocessor to tens, hundreds, even thousands of digital and analog outputs. It should be fun :)

There are still some spots left in the class, so don't hesitate to sign up at http://la.thepublicschool.org/class/256. There are also a few days left to sign up with a 10% discount for the Practical Electro-Mechanisms class in June.

For those of you who are hesitant to take the class due to cost, we always try to accommodate requests for assistance, exchange of services or barter proposals written to dan at thepublicschool.org. All the class fees currently go in support of The Public School, a non-profit organization.

totally interested, but I'm gonna be at LayerOne that day :(

I'll look into the Practical Electro-Mechanisms class :)

In case some of you on the interest list haven't noticed it, this class has been scheduled for May 23rd (11am-2pm). Please sign up by going to the class page (http://la.thepublicschool.org/class/256) and following the "buy now" google checkout button. If anyone had trouble with the sign-up button earlier, it should be fixed now!

PS. Another 8-bit Lab class that has just been scheduled is "Practical Electro-Mechanisms" (http://la.thepublicschool.org/class/233), on June 20th.

PPS. Yes, we'll definitely play around with multiplexer and shift register chips, among others :)

With this class, it would be great to play with 4051 multiplexer/demux and the 795 shift registers chips. hint hint. ;)