1. Both ISP and JTAG interfaces are extracted and labeled;
2. AD conversion reference voltage is added with filter inductor and capacitor;
3. Two frequency external crystal oscillators can be selected by jumpers;
4. All IO ports are drawn and marked;
5. Reliable reset circuit;
6. Lead up to four LEDs for simple testing;
7.miniUSB or pin power supply;
8. Double-sided copper coating to improve the stability of the board;
9.PCB specification: 49×69 (mm)