You might investigate a multiplexing solution.

With 16 I/O lines the direct method would only provide 16 outputs for 16 LEDs using a current limiting resistor for each LED.

I haven't seen any examples for the SX for using a 64 LED driver like the MAX7219 but I'm sure it can be done. There are many examples for the Basic Stamp 2 (BS2). I even worked on a multi-IC (MAX7219) version (128 or more LEDs with 2 or more MAX7219) for the BS2.

The easiest approach is to use (8) 74HC595 IC's which allow you to control 8 LEDs at a time for each IC using a simple SHIFTOUT command for each 74HC595.

The downside to using the 74HC595's is that there are 8 of them compared to only 1 MAX7219.

Many other possibilities are possible but those are the ones I see used most often here.

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JonnyMac has schematic, board layout and code for driving an 8x8 LED matrix from an SX28 using almost no parts (8 resistors, basically). His code includes animation frames, scrolling text, etc. The rest of the program deals with running the "game of life" and scanning some button inputs, so you may not need that part.

However, if you are using high-current LEDs you may want to use a transistor driver (like the ULN2803) to drive the 8 columns.

[Quoting: "Somebody"] 64 LED driver like the MAX7219

That said, a roll-your-own matrix driver in an SX would let you do full 8bit PWM, and you'd be able to match led resistance to your banks of leds.

If you want full discrete control, you could cascade your own SXs, you could do 16 leds per SX and roll-your-own code to do full PWM on each led. Use RA.0...RA.3 for /CE, Din, Dout, /OE (or serial). Basically your SX would behave like a cascated shift register but with PWM on the pins... you could pass 16 bytes for each driver -- each byte being PWM value 0..255 for each LED. 0 would be off, 255 on. And you could certainly do that at 4MHZ w/o an external resonator (save more parts per chip).

8 SX chips x 2.79 = a bit less than $20
Maxim also makes some discrete LED drivers, in the 8-20 led per chip range, but I think they around $8, so using 4-8 of those could get a bit pricier (but there would not be the programming chores).

With the ubiquitous 74HC595 (eight of them in series), you could drive all 64 LEDs (at low current) with three I/O lines. By using eight parallel data lines, plus the clock line and transfer line, you'd be able to get data into the 74HC595s'  output registers a lot more quickly. Depending on the current draw from your LEDs, you may also need some transistor buffering. If that proves cumbersome, TI makes a high-current, open-drain version of the 74HC595: the TPIC6595.

Hi All;
And of course, if you used "charlie-plexing", you could drive two banks of 42 LEDs straight out of one SX directly, using no external logic or drivers, and only 14 pins and 14 resistors. Naturally, a bit of multiplexing software is required, but then that's the fun part isn't it?

Peter -- I had forgotten about Charlie-plexing....thanks for the reminder.

If you haven't heard of Charlie-plexing, it takes advantage of the tri-state properties of micro pins -- it's actually a really good candidate for the SX...