Power pin
- Vcc
- GND
External crystal pin
- clock
Control and reset pins
- ALE access to external storage or external expansion
- RD and WR
- RESET
I / O pull leg
There are 62 stc15
I/O port working mode
- Quasi-bidirectional port (default)
- Push-pull output (large current)
- Input only (high resistance)
- Open drain (external)
Initialize I/O
- PxM1
- PxM0
