There are also a few modifications in the schematic diagram. Instead of direct driving of anode P-channel FETs (T1-T8) for the LED matrix, there is 3-to-8 decoder 74HC138 (U3). It uses only four instead of eight I/O ports of the MCU, and the remainig ports are available at the expansion connector CON3.
All other components are the same as on the Belgrade badge.
CPU clock is 48 MHz (which is 12 MIPS), so display refresh takes about 1% of processor time. Infrared transmitter is the single 940 nm LED, and the receiver is TSOP6240, which contains photodetector, AGC preamplifier, 40KHz band-pass filter and demodulator.
Microchip designed the new bootloader firmware for the badge, so when it is connected to the USB port, PC "sees" the badge as the disk and you can simply drag and drop HEX file with your firmware to the disk icon, named HackABadge. Thanks Microchip, good job!