smbaker
05-26-2010, 12:40 AM
Since there was a discussion the last week or two about interfacing a LED matrix to a prop, I thought I'd share my latest prototype. It's Conway's Game of Life implemented on a prop with an 8x8 LED matrix.
The anodes were sourced via 100 ohm resistors directly from the prop. Cathodes were sinked via a ULN2803 darlington array. I operated the display in a straightforward common-cathode manner, energizing the cathodes one at a time while setting the appropriate 8 anode bits. The design used 16 IO lines from the prop. As discussed in the other threads, this could certainly have been reduced by using latches or shift registers. However, the sole purpose of the board was to operate the display, so only half of the prop's IO pins were even needed.
There are empty pads for mounting a dallas RTC, and headers for joining multiple boards into a grid should I ever choose to do so.
It's also my first SMD board, and I'm pleased to say that I assembled it correctly and it powered up the first time with no problems!
If I'd had it to do over again, I might have mounted the display to the opposite side of the board rather than putting it on the same side as the components.
The anodes were sourced via 100 ohm resistors directly from the prop. Cathodes were sinked via a ULN2803 darlington array. I operated the display in a straightforward common-cathode manner, energizing the cathodes one at a time while setting the appropriate 8 anode bits. The design used 16 IO lines from the prop. As discussed in the other threads, this could certainly have been reduced by using latches or shift registers. However, the sole purpose of the board was to operate the display, so only half of the prop's IO pins were even needed.
There are empty pads for mounting a dallas RTC, and headers for joining multiple boards into a grid should I ever choose to do so.
It's also my first SMD board, and I'm pleased to say that I assembled it correctly and it powered up the first time with no problems!
If I'd had it to do over again, I might have mounted the display to the opposite side of the board rather than putting it on the same side as the components.