The 68HC11 is a powerful 8-bit data, 16-bit address microcontroller from Motorola with an instruction set that is similar to the older 68xx (6801, 6805, 6809) parts. Depending on the variety, the 68HC11 has built-in EEPROM/OTPROM, RAM, digital I/O, timers, A/D converter, PWM generator, and synchronous and asynchronous communications channels (RS232 and SPI). Typical current draw is less than 10mA.
Architecture
The M68HC11 is optimized for low power consumption and high-performance operation at bus frequencies up to 4 MHz. The CPU has two 8 bit accumulators (A & B) that can be concatenated to provide a 16 bit double accumulator (D). Two 16 bit index registers are present (X & Y) to provide indexing to anywhere in the memory map. Having the two index registers means the 68HC11 is very good for processing data. Although an eight bit processor, the 68HC11 has some 16 bit instructions (add, subtract, 16 * 16 divide, 8 * 8 multiply, shift, and rotates). A 16 bit stack pointer is also present, and instructions are provided for stack manipulation. Typically multiplexed address and data bus.
Other features include:
- Powerful bit-manipulation instructions
- Six powerful addressing modes (Immediate, Extended, Indexed, Inherent and Relative)
- Power saving STOP and WAIT modes
- Memory mapped I/O and special functions
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Marco de Wilt, 1997