Features Compatible with MCS 51 Products 4K Bytes of Reprogrammable Flash Memory Endurance: 10,000 Write/Erase Cycles 2.7V to 6V Operating Range Fully Static Operation: 0 Hz to 24 MHz Two-level Program Memory Lock 128 x 8-bit Internal RAM 15 Programmable I/O Lines 8-bit Two 16-bit Timer/Counters Six Interrupt Sources Microcontroller Programmable Serial UART Channel Direct LED Drive Outputs with 4K Bytes On-chip Analog Comparator Low-power Idle and Power-down Modes Flash Brown-out Detection Power-On Reset (POR) Green (Pb/Halide-free/RoHS Compliant) Packaging AT89C4051 1. Description The AT89C4051 is a low-voltage, high-performance CMOS 8-bit microcontroller with 4K bytes of Flash programmable and erasable read-only memory. The device is man- ufactured using Atmels high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set. By combining a versa- tile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C4051 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89C4051 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five-vector, two-level inter- rupt architecture, a full duplex serial port, a precision analog comparator, on-chip oscillator and clock circuitry. In addition, the AT89C4051 is designed with static logic for operation down to zero frequency and supports two software-selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The power-down mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset. 1001FMICRO6/082. Pin Configuration 2.1 PDIP/SOIC RST/VPP 1 20 VCC (RXD) P3.0 2 19 P1.7 (TXD) P3.1 3 18 P1.6 XTAL2 4 17 P1.5 XTAL1 5 16 P1.4 (INT0) P3.2 6 15 P1.3 (INT1) P3.3 7 14 P1.2 (TO) P3.4 8 13 P1.1 (AIN1) (T1) P3.5 9 12 P1.0 (AIN0) GND 10 11 P3.7 3. Block Diagram 2 AT89C4051 1001FMICRO6/08