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???
11/05/09 19:33
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Msg Score: +1
 +1 Informative		 #170468 - Unfortunately,...
Responding to: ???'s previous message
...that's a typical real life behaviour.

Somewhere in the design there's very probably a weak point, a design mistake, resulting in a decrease of noise margin of a certain digital signal. This can be crosstalk within the cable, ringing due to the lack of proper cable termination, injecting of hum and EMI via stray capacitance caused by improper shielding, and, and, and.

By touching GND of the circuit you intensify the noise level and the noise margin gets destroyed finally, resulting in a pin appearing as a "0" which should actually be a "1", or vice versa.

Kai Klaas

List of 30 messages in thread
TopicAuthorDate
C2 debugger interface resets when ground pin is touched            01/01/70 00:00      
   Flash operations            01/01/70 00:00      
      one point            01/01/70 00:00      
         WDT and flash            01/01/70 00:00      
            do you have a 4 layer board, is the PC and ...            01/01/70 00:00      
               GSM modem, not PC..            01/01/70 00:00      
                  Floating signals            01/01/70 00:00      
                  PC "ground" loop?            01/01/70 00:00      
                     That is a good point!!            01/01/70 00:00      
                  Perhaps you should "AC-couple" signal GND to "earth"            01/01/70 00:00      
   Maybe your compy USB is flakey?            01/01/70 00:00      
      apples and oranges            01/01/70 00:00      
   No surprise at all!            01/01/70 00:00      
      Actually, it resets when I am nowhere near it also.            01/01/70 00:00      
         Unfortunately,...            01/01/70 00:00      
         Section 11.3 of the datasheet            01/01/70 00:00      
            known as 'design specifications'            01/01/70 00:00      
               Another clarification..            01/01/70 00:00      
               Design specs eh            01/01/70 00:00      
                  which is ridiculous and "asking for it"            01/01/70 00:00      
                     SICKLabs...            01/01/70 00:00      
                     /RST cap            01/01/70 00:00      
   Your power supply looks instable?            01/01/70 00:00      
      Unstable supply?            01/01/70 00:00      
         Supply            01/01/70 00:00      
            wrong approach            01/01/70 00:00      
         good catch AP            01/01/70 00:00      
      Indeed!            01/01/70 00:00      
      An easy test            01/01/70 00:00      
         oh, but it does            01/01/70 00:00      

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