LED-1 is a peripheral board with four 7-segment LED displays with decimal point. The segment LEDs are placed on sockets and can be replaced easily. All four digits on the board are controlled via an I2C 2-wire serial interface.
The I2C interface lines and the 5V power supply connections are available on a 20-pin (2×10) expansion connector for interfacing to existing microcontroller systems. This board can be connected either as a piggyback daughterboard on a microcontroller board (one with a matching connector) using standoffs or can be placed away from the microcontroller board using a 20-wire ribbon cable.
The expansion connector is plug-in compatible with MicroTRAK, MINI-MAX and BSCB systems. You can use it in your own system too, of course; see the manual for the expansion connector's pinout.