电源关闭几秒后，Ram数据不会初始化

亲爱的大家，
 
我现在正在研究stm8af51bb宏芯片。根据用户手册，wo可以将数据保存在一个特殊的RAM区域，并在芯片复位后保持数据未初始化。真的，我们已经意识到这个功能。
但现在出现了另一个问题：一旦芯片正常工作，突然发生低功率脉冲----我的意思是芯片可能会在几秒钟内失去电源，那么我怎样才能将数据保持在未初始化的特定RAM区域？需要特殊的电路支持来实现这个功能吗？
 
感谢所有人。



以下为原文




Dear all,

I'm now working on stm8af51bb macro chip.According to user manual,wo could keep data in a special RAM area and left the data uninitialized after a chip reset. Truely we've realized this function.  
But now comes up another problem: Once chip is normally working, a sudden low power pulse occurs----I mean chip may lose power supply for seconds,then how could I keep the data in a specific RAM area uninitialized? Need a special circuit support to realize this function?  

Thx for all.

你好floodever，
 
 
从你的描述来看，问题不是很清楚。我想你的意思是：
- 即使电源电压下降，RAM也应保留您之前写入的数据。
它是否正确 ？
 
如果是，那么您需要考虑保持RAM内容不能保证低于2.6V。未定义低于此电压的RAM会发生什么。
 
为了使数据保持在电压变为褐色，您需要
- 确保在此期间微电压的VDD不会降至2.6V以下
- 或使用内部NVM（数据EEPROM）存储数据。因此，更新RAM中相关数据的频率非常重要。
 
 
如果它很少更新（假设在应用程序的生命周期内高达100k时间），那么您可以将相关数据直接存储在EEPROM中
如果更频繁更新，则需要遵循另一种策略：监控电源电压，如果电压低于标称电压，则需要在电压低于3.0V的最低工作电压之前将相关数据写入EEPROM 。当然，这种策略需要正确确定滤波电容的尺寸和低功耗策略。
 
 
在深入了解之前，请告诉我们更多细节。
 
祝你有美好的一天
 
亚历山大
 
 
[此消息由：alexanderc于04-06-2009 09:48编辑]



以下为原文




Hello floodever,


from your description, the problem is not very clear. I guess that you mean the following:  
- the RAM shall keep the data you have written previously, even if the supply voltage is going down.  
Is this correct ?  

If yes, then you need to consider that keeping the RAM content cannot be guaranteed below 2.6V. It is undefined what happens to the RAM below this voltage.  

In order to keep data over a voltage brown out, you need to  
- either ensure that the VDD of the micro does not drop below 2.6V during this time  
- or use the internal NVM (data EEPROM) to store the data. It then is important how frequently you update the concerned data in the RAM.  

• If it is updated rarely (let's say up to 100k time during the life of the application), then you can store the concerned data directly in EEPROM  
  
• If it is updated more frequently, you need to follow another strategy: Monitor the supply voltage and if the voltage drops below the nominal one, you need to write the concerned data to the EEPROM before the voltage falls below the minimum operating voltage of 3.0V. Of course this strategy needs correct dimensioning of the filter capacitors and low power strategy.  
    
    
  OK before going more in depth, let us know more details.  
    
  Have a good day  
    
  Alexander  
  
  
  [ This message was edited by: alexanderc on 04-06-2009 09:48 ]
  

亲爱的亚历山大，
 
 
非常感谢您的详细回复。
现在我忙于IAP程序，所以这个问题被推迟处理。我会根据你的上一个回复做一些测试，然后给你发送更多细节。
顺便说一句，我们的系统电源是3.3v（VDD），保持RAM数据的阈值电压是否仍然是2.6v？对不起，我们在这个微芯片（STM8AF51BB，100pin，256KBytes flash）上没有详细的电气特性。
 
Thansk＆amp;最好的祝福。



以下为原文




Dear alexanderc,


Great thanks for your detailed reply.  
Nowadays I'm busy on IAP program,so the issue was postponed to deal with.I'll do some test based on your last reply and then send you more details.  
By the way,our system power supply is 3.3v(VDD),so is the threshold voltage for keeping RAM data still 2.6v? I'm sorry that we didn't have detailed electrical characteristics on this micro chip(STM8AF51BB,100pin,256KBytes flash).  

Thansk & Best regards.