我们公司用的MCU是mc9s12hz256val这款单片机开发了一款工业控制设备，现在出现了一下现象 1、用对讲机测试空中电磁干扰MCU马上复位。2、复位之后有的时候可以正常启动运行，有时MCU就无法正常启动。怀疑晶体问题后换爱普生有源晶体一样

[2841287897]

我们公司用的MCU是mc9s12hz256val这款单片机开发了一款工业控制设备，现在出现了以下现象 1、用对讲机测试空中电磁干扰MCU马上复位。2、复位之后有的时候可以正常启动运行，有时MCU就无法正常启动。怀疑晶体问题后换爱普生有源晶体一样出现此问题。  3、加了外部看门狗连接BDM需要注意的问题，是否有外部看门狗在下载程序必须分离吗？（应看门狗连接用BDM不可以下载程序）

请问这款MCU的级别？    有没有比此款MCU级别高的？    这些问题怎么处理？   谢谢静候  邮箱：2841287897@qq.com

Our company use the MCU is Mc9s12hz256val the SCM developed an industrial control equipment, now appeared the following phenomenon 1, electromagnetic interference with radio test air MCU reset immediately.2, sometimes can run normal boot after reset, sometimes MCU cannot be normal boot.Suspect crystal problem in epson after active crystal appear this problem.3, plus external watchdog connection BDM need to pay attention to the problem, whether there are external watchdog in the download program must be separated?(should be the watchdog connected with BDM can not download the program)

The level of the MCU, please?     Is there any higher than this level of MCU?       How to deal with these issues?                                                   Thank you for waiting for email: 2841287897 @qq.com

[RadekS]

Hi 勇 李,

1. The reset source should be detected as first. You may create separate startup routines for CM, COP and Other reset sources. In that case, please check external RC circuit at RESET pin. The bit capacitance at RESET pin might block correct recognition of reset source. For more details, please check https://community.nxp.com/docs/DOC-103737. The Other reset sources (POR and LVR) could be detected by CRGFLG register.

Note: S12HZ do not have Illegal address reset.

2. Please check capacitance at reset pin according to previous point. Please check whether you defined all three reset vectors. Please, check your configuration for self-clock mode and clock monitor reset (PLLCTL register, CME and SCME bits). Injected high energy into clock circuit might cause a clock lack (depends on circuit parameters and board layout), therefore CM and SCM features was implemented.

Please check also PE7 pin level according to your oscillator settings (Colpitts/Pierce).

3. If you use external watchdog, you should somehow prevent against unwanted MCU reset during MCU programming = when external watchdog is not triggered by MCU. The safest way is mechanical disconnection between external watchdog and MCU RESET pins. The next possible options are inhibiting external watchdog by external voltage or external triggering watchdog during programming. Here it depends on external watchdog features. The internal watchdog is typically inhibited by one of first debuggers command (like “wb 0x03c 0x00  //disable cop”)

I hope it helps you.

Have a great day,
Radek

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