SIMHC12 is a simulator program for the Freescale/Motorola 68HC12. It simulates the M68HC12A4EVB evaluation board which contains an MC68HC812A4 microcontroller, 16k of external RAM and 32k of external ROM. The 68HC812A4 microcontroller simulation can run in Expanded Wide, Expanded Narrow, or Single Chip modes. SIMHC12 will also simulate the M68HC912B32 running in Single Chip mode.

Features

The user has access to one serial port via a terminal emulator, as well as the Analog to Digital Converter, Timer Module (and Port T), Ports H and J (as well as D, A, and B depending on operating mode), IRQ, XIRQ, and the peripheral chip selects CS0 through CS3. The COP timer, internal RAM and EEPROM, and the full instruction set are implemented. Instruction timing is emulated, and clock stretch can be applied for all the chip selects.

A debugger is provided with the ability to step execution, step over subroutines, set any number of breakpoints, load S19 format files, and examine and modify registers and memory. The debugger is capable of stopping execution upon invalid memory accesses, uninitialized interrupt vector execution, and invalid instructions.

New Features added May 2005

The current SIMHC12 provided on the CD has features which until now were only in the 68HCS12 simulator:

• Choice of source listing or disassembled source in viewers
  
• Breakpoint set and clear from source listing/ disassembled source
  
• Set PC and memory display using source program labels
• Instruction Trace so you can work backwards from a "crash".
• Much faster performance when updating the display while executing (typically several times faster) and when simulating an interrupt driven program (up to 30% faster).

For version changes changes, look here.

The Free Alternative

A free, earlier version of this simulator, is available (without the textbook) here. If you are using the 68HCS12 you should be looking at the 68HCS12 Simulator.

Questions? Contact me at support4@hcs12text.com