AT89S51 Microcontroller

The AT89S8253 is a 8-bit low-power high-performance CMOS Microcontroller with 12kB of In-System Programmable (ISP) flash program memory and 2kB of EEPROM data memory. The device is manufactured using Atmel's high-density non-volatile memory technology and is compatible with the industry-standard MCS-51 instruction set and pinout. The on-chip downloadable flash allows the program memory to be reprogrammed in-system through an SPI serial interface or by a conventional non-volatile memory programmer. By combining a versatile 8-bit CPU with downloadable flash on a monolithic chip, the Atmel AT89S8253 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications.

The P89V51RD2 is an 80C51 microcontroller by NXP (Phillips) with 64 kB Flash and 1024 bytes of data RAM. A key feature of the P89V51RD2 is its X2 mode option. The design engineer can choose to run the application with the conventional 80C51 clock rate (12 clocks per machine cycle) or select the X2 mode (6 clocks per machine cycle) to achieve twice the throughput at the same clock frequency. Another way to benefit from this feature is to keep the same performance by reducing the clock frequency by half, thus dramatically reducing the EMI. The Flash program memory supports both parallel programming and in serial In-System Programming (ISP). Parallel programming mode offers gang-programming at high speed, reducing programming costs and time to market. ISP allows a device to be reprogrammed in the end product under software control. The capability to field/update the application firmware makes a wide range of applications possible. The P89V51RD2 is also In-Application Programmable (IAP), allowing the Flash program memory to be reconfigured even while the application is running.