S12 / MagniV MicrocontrollersのトピックRe: About S12G128 EEPROM

About S12G128 EEPROM

kimkang-mok — Wed, 25 Oct 2017 17:23:33 GMT

Hi, Actually I want to know why CAN and UART has problem when I use Initialize CLK for EEPROM.

I follow the S12GN32's EEPROM Code.

My PLL Bus CLK is 32Mhz. I use 125kbps CAN Speed and baud 9600 UART Communication.

The symptoms of my program are as follows:

1. When I except EEPROM Initializing code, My CAN function and UART function is working.

2. When I include EEPROM Initializing code, My CAN function and UART function is not working.

I need all three functions.

How can I solve this problem?

Re: About S12G128 EEPROM

RadekS — Thu, 26 Oct 2017 12:37:02 GMT

Hi Kim,

The question is what your EEPROM Initializing code does. Could you share your EEPROM Initializing code here?

In fact, the maximum bus clock frequency for an S12G family is just 25MHz.

So, when you overclock MCU and “initialize EEPROM”, the clock may be reconfigured or simply unlocked and unstable.

Please do not use bus clock higher than 25MHz for S12G MCUs.

I would like to also recommend using an external oscillator as the source clock for CAN module instead of PLL.

I hope it helps you.

Have a great day,
Radek

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: About S12G128 EEPROM

kimkang-mok — Thu, 26 Oct 2017 13:33:58 GMT

Thank you for your interest in my post.

I already solve this problem.

My problem arose due to changes in Clock speed.

Thank you for your kindness.

Re: About S12G128 EEPROM

TurboBob — Sat, 09 Dec 2017 07:56:23 GMT

Radek:

You said :

I would like to also recommend using an external oscillator as the source clock for CAN module instead of PLL.

do you mean that an 8mhz crystal is not suitable for CAN applications? I looked thru the reference manual and could find no recommendations.

thank you

Bob

Re: About S12G128 EEPROM

RadekS — Mon, 11 Dec 2017 08:28:46 GMT

Hi Bob,

No, the meaning is exactly opposite.

The 8mhz crystal is suitable as CAN clock source in most of the cases.

The PLL clock is suitable as CAN clock source rather only for debugging purposes.

For real application, the crystal should be used as the clock source.

The difference is in accuracy. The internal IRC clock have accuracy +/-1.3%. The PLL unlock detection is between 0.5 and 2.5%. So, the PLL based on IRC may not fulfill clock CAN accuracy requirements on edge cases.

I hope it helps you.

Have a great day,
Radek

Re: About S12G128 EEPROM

TurboBob — Sat, 13 Jan 2018 23:37:35 GMT

Thank you for clarifying. It makes sense. I posted in another (old) thread, not sure I will every get a reply. That question was if there is a patch or port of the AN2295 bootloader for the '12s

thanks

Bob Bailey