In this schematic (it is of a board from Adafruit, I included the link below) what is the diode's purpose? Originally, I thought it was to only allow for an logic signal from the Reset Pin, but then, wouldn't the diode be placed in the opposite direction? I am not really an Electrical Engineer, just curious.


Full Schematic:





Your first thought is correct.

  • If RST_5V is left floating, R10 will pull NRESET_3V up to 3.3v.
  • If RST_5V is driven low, current will flow through the diode and NRESET_3V will be pulled to ground
  • \$\begingroup\$ Thank you for your answer. Quick follow up: what do you mean by "floating"? \$\endgroup\$ – Theodore_Kim Mar 9 '17 at 22:23
  • \$\begingroup\$ Not actively driven \$\endgroup\$ – fkoran Mar 9 '17 at 22:25
  • \$\begingroup\$ Ok, what if the input is driven high, what would be the effect? (last question, I promise :) ) \$\endgroup\$ – Theodore_Kim Mar 9 '17 at 22:26
  • \$\begingroup\$ No worries! I'm here to slack :) If the input is driven high, no current will flow through the diode. High is sort of a default state, so there's no need to actively drive that line \$\endgroup\$ – fkoran Mar 9 '17 at 22:26

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