I set out to program a PIC to implement an I²C-controlled 4-digit 7-segment LED display because I thought it would be a decently nontrivial practice project to help me learn. I had fully expected it to end up duplicating the functionality of a commercially available product that does it better for a fraction of the price.
Now that my project is in a decently functional state, I went looking for that commercial product to see what else I can try to imitate for the sake of practice. I was surprised that nothing immediately stood out as both “does it better” and “fraction of the price”.
The first item I found was sold by Adafruit. They have an I²C LED display “backpack” in various colors. Here’s the green version, as one example. The driver chip they used is the MAX7219, which I found curious because the data sheet for the chip does not mention I²C communication. Another curious item is that the complete kit – including populated circuit board and LED – has a list price of $9.95 but if I want to buy the MAX7219 by itself from Adafruit it costs the same $9.95. Digi-Key sells the chip for around the same price. I doubt Adafruit get their circuit board and LED for free, so there’s something else I’m missing.
But I couldn’t have used that chip anyway. The MAX7219 is for driving a display unit with common cathode, and LTC-4627JR is a common anode unit. Also, Maxim is telling people to migrate their designs to the MAX6950, which seems to be a surface-mount only chip with no DIP form factor available.
Looking over Sparkfun catalog I found a similar product, but theirs is controlled by an ATMega328 chip. In fact, it is a baby Arduino complete with the Arduino bootloader. This is closer to what I’ve built, but I think the PIC is a simpler and less expensive chip to perform the task which may mean a small niche below the Sparkfun unit.
All this hints at the possibility my project might actually find an audience as a product. If I were to go ahead with this, I would test the market by putting it up on Tindie. It’s a marketplace that seems to cater to the right audience and there doesn’t seem to be a direct competitor product at the moment.
Well, that was unexpected. I might as well keep going and see how far I can take this.