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Jim Granville
08/28/13 16:30
Read: 1095 times

#190011 - RST and Full speed ?
Responding to: Mikkel C. Simonsen's previous message
Mikkel C. Simonsen said:
... I have discovered another bug/feature. If the supply voltage rises slowly, the internal oscillator runs at double speed sometimes. If the rise time is low, the problem doesn't happen. The IC is supposed to have an internal reset circuit, that should take care of this problem...

If you reload the Clock Divider on some pin change, or serial command, does that restore the expected operation ?

The STC info suggests they defaulted to No-divide, which is not so clever on a slowly rising supply - the RST may release <before/u> the CPU can run at 35MHz.
What voltage does it release RST at ?

Most vendors default to a slower speed, then rise it later.

The LP52 looks quite good here, because it is such a low speed, it seems to always be OK, even close to the 2.0V BOD level.
I also found it wakes up well, on an external level, from sub 1uA Power Down.

List of 12 messages in thread
STC 15F104E      Mikkel C. Simonsen      08/17/13 18:47      
   The STC12C5Axxx work fine      David Prentice      08/18/13 02:24      
      Others      Mikkel C. Simonsen      08/18/13 15:26      
   Support from STC?      Andy Neil      08/25/13 11:34      
      Support?      Mikkel C. Simonsen      08/27/13 21:02      
         Just Email STC      David Prentice      08/28/13 11:07      
            Who am I e-mailing?      Mikkel C. Simonsen      08/28/13 11:46      
               I guess SiliconRay is same as STC      David Prentice      08/28/13 16:03      
         RST and Full speed ?      Jim Granville      08/28/13 16:30      
            Divider      Mikkel C. Simonsen      09/04/13 15:52      
               LP52      Jim Granville      09/09/13 23:28      
   USB programming works      Mikkel C. Simonsen      09/04/13 15:59      

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