Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
11/03/09 21:17
Read: times


 		 #170399 - No surprise at all!
Responding to: ???'s previous message
Raj said:
C2 debugger interface resets when ground pin is touched.


You must not touch certain points of a printed circuit board, if this results in a current spike running through the board or the cabling!!! That's why metallic enclosures are used with screened cables with the cable screen bonded to enclosure. Then, interference, hum or ESD hits the shield and flows arround the circuitry, but not across the board and within the cable.

In your case you either discharge into the cable running to the earthed PC or you offer the PC a current path to earth vice versa, if the PC has no good connection to earth. Some hundreds of millivolts running over a signal ground line between two devices are enough to erode the noise margin anywhere, which can easily make your micro do things you don't want.

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      

Back to Subject List