fpga4fun.comwhere FPGAs are fun

Opto 5 - LED dot-matrix displays

LED displays are also commonly available in "dot-matrix" form.

Internally, the LEDs are organized in a matrix. Here's a 5x7 display internal wiring (requires a minimum of 13 pins, likely to be shipped in a 14 pins package).

A multiplex driver is required. For example, you might want to scan the 7 rows, and send data through the 5 columns. Do that fast enough (100Hz at least) and nobody will notice the multiplexing. Remember that power transistor might be required (at least for the rows) since FPGA IOs are unlikely to provide enough current.

Most dot-matrix displays come in 5x7, 5x8 or 8x8 form, and can be used to form bigger displays. Here's what can be done with a little work.

Your turn to experiment!