DESCRIPTION
The 89C51RB2/RC2/RD2 device contains a non-volatile 16kB/32kB/64kB Flash program memory that is both parallel programmable and serial In-System and In-Application Programmable. In-System Programming (ISP) allows the user to download new code while the microcontroller sits in the application. In-Application Programming (IAP) means that the microcontroller fetches new program code and reprograms itself while in the system. This allows for remote programming over a modem link. A default serial loader (boot loader) program in ROM allows serial In-System programming of the Flash memory via the UART without the need for a loader in the Flash code. For In-Application Programming, the user program erases and reprograms the Flash memory by use of standard routines contained in ROM. This device executes one machine cycle in 6 clock cycles, hence providing twice the speed of a conventional 80C51. An OTP configuration bit lets the user select conventional 12 clock timing if desired.
This device is a Single-Chip 8-Bit Microcontroller manufactured in advanced CMOS process and is a derivative of the 80C51 microcontroller family. The instruction set is 100% compatible with the 80C51 instruction set.
The device also has four 8-bit I/O ports, three 16-bit timer/event counters, a multi-source, four-priority-level, nested interrupt structure, an enhanced UART and on-chip oscillator and timing circuits.
The added features of the P89C51RB2/RC2/RD2 makes it a powerful microcontroller for applications that require pulse width modulation, high-speed I/O and up/down counting capabilities such as motor control.

FEATURES
• 80C51 Central Processing Unit
• On-chip Flash Program Memory with In-System Programming
   (ISP) and In-Application Programming (IAP) capability
• Boot ROM contains low level Flash programming routines for downloading via the UART
• Can be programmed by the end-user application (IAP)
• 6 clocks per machine cycle operation (standard)
• 12 clocks per machine cycle operation (optional)
• Speed up to 20 MHz with 6 clock cycles per machine cycle
   (40 MHz equivalent performance); up to 33 MHz with 12 clocks per machine cycle
• Fully static operation
• RAM expandable externally to 64 kB
• 4 level priority interrupt
• 8 interrupt sources
• Four 8-bit I/O ports
• Full-duplex enhanced UART
   – Framing error detection
   – Automatic address recognition
• Power control modes
   – Clock can be stopped and resumed
   – Idle mode
   – Power down mode
• Programmable clock out
• Second DPTR register
• Asynchronous port reset
• Low EMI (inhibit ALE)
• Programmable Counter Array (PCA)
   – PWM
   – Capture/compare