topic Re: S08RN Trim values in 8-bit Microcontrollers

S08RN Trim values

jochengerster — Mon, 20 Nov 2017 08:49:35 GMT

I found following information about S08RN trimming but I have some question were I'm not 100% sure and if my understanding is correct:

1) Factory reserved memory location is not accessible (read/write) by user?

2) The conventional location at 0xFF6E is blank 0xFFs when part is shipped?

3) If conventional location 0xFF6E is used the user SW must read it and write it to ICS_C3?

"For S08RN, All MCU devices are factory programmed with a trim value in a factory reserved memory location. This value is uploaded to the ICS_C3 register and ICS_C4 register during any reset initialization. That means you don't need to initialize ICS_C3 in your software.

However, if you want to use other trim values, the conventional location is 0xFF6E-0xFF6F, P&E tools will program new trim value in those addresses.

By the way, the RN60 factory trim value is 39.0625 kHz"

Thanks for your help

best regards

Jochen

Re: S08RN Trim values

tonyp — Mon, 20 Nov 2017 09:17:40 GMT

1. The trim value is stored in Flash (some predefined location by convention to make it easier for programmers to know where to store it automatically). Since this is Flash you can manipulate as any other Flash location. However, a trim value normally would not have to be changed after initial calculation. That's why a location up in high address space which is usually protected to protect a bootloader is the ideal solution.

2. I don't know about this particular MCU variant but more recent parts have been shipping pre-trimmed. So, in those cases the trim value will not be FF. If using a programmer that can calculate the trim value for you (like Cyclone PRO) then the programmer may replace the factory trim value with a different one.

3. Correct. This is one of the first steps during MCU initialization. Now, I read in your quote this particular part may do it automatically for you. I don't know. But, it wouldn't hurt to do it manually to be sure it gets loaded correctly.

Re: S08RN Trim values

jochengerster — Mon, 20 Nov 2017 15:51:13 GMT

Thanks for your reply but I need to know exactly how the trimming is implemented on S08RN

Can someone from NXP Apps please have a look at this

1) Factory reserved memory location is not accessible (read/write) by user?

1 a) Is this reserved memory location the IFR so user can't by mistake overwrite it?

2) The conventional location at 0xFF6E is blank 0xFFs when part is shipped?

3) If conventional location 0xFF6E is used the user SW must read it and write it to ICS_C3?

Thanks again

Jochen

Re: S08RN Trim values

vicentegomez — Mon, 27 Nov 2017 18:52:24 GMT

Hi Jochen

I already send you some information, I will continue with the support directly to you.

regards

Vicente Gomez