Does anyone have experience moving from HC11 to newer part?

[mikekolb]

Hi, I have a large number of products that use a HC11 microcontroller, specifically a MC68HC711E9CFN2, which we are still building and selling to our customer.  I don't plan on adding additional capability to these products, but I do need to find the least painful way to upgrade to a new microcontroller.  Has anyone else had a similar experience and what parts did you go to?

[Lundin]

I've upgraded from HC11 E9/E20 to S12 in the past. It was a pure assembler project, so there were no other options (as there would have been, had it been written in C). The major difficulties we experienced were related to hardware peripherals.

The main thing to consider when porting is the different memory layout, where banked memory etc. is possible. And particularly the EEPROM, which works quite differently. If you are using the EEPROM of the HC11, you need to consider which S12 part to migrate to very carefully.

The earliest released S12 derivates like S12D have on-chip EEPROM, but since that family was released 10 years ago, it is otherwise somewhat old-fashioned today: no on-chip low-voltage detect, 10-bit ADC, numerous unresolved silicon bugs, peculiar, mildly useful on-chip PWM etc etc. I wouldn't recommend this part for new designs, but Freescale stubbornly refuses to put any EEPROM or data flash in newer parts. If EEPROM is important to you, you must either consider external EEPROM circuitry, or look beyond Freescale for alternative MCUs.

[kef]

It depends on your source code. If you have lots of assembler, then you may save a lot of time migrating to S12(X), which has the same set of CPU registers and source level comparible instructions set. Also try looking at S12(X) timer, SPI and SCI modules, and compare registers set and functionality to HC11. I'm sure you won't have problems upgrading you HC11 code to S12(X).