I have a wifi transciever(ESP8266) which should be connected to 3.3v and microcontroller connected to 5v(PIC16).

For establishing the communication between the microcontroller and wifi they should share a common ground. So while working on the circuit sometimes wifi is consuming more current and the chip is getting heated and no communication happens.

If I reconnect the power of wifi and microcontroller again the circuit is fine.

This problem(heating up the wifi) occuring multiple times while giving 3.3v regulator(AMS1117,3v3 reg). So to reduce that I gave two separate power sources one 3.3v and one 5v power supply.

uC circuit:
enter image description here

WiFi circuit:
enter image description here

Where will be the problem of current consumption?

Is it wifi problem or ground problem?

  • \$\begingroup\$ sounds like you are chasing two different issues, or while solving one it breaks something else. There must be a common ground between all supplies and microcontroller/wifi modules if you want them to actually work properly. \$\endgroup\$
    – KyranF
    Feb 9 '16 at 4:44
  • \$\begingroup\$ @KyranF yes i have connected a common ground between wifi and uC. The problem is occurring sometimes only. \$\endgroup\$
    – Honeybee
    Feb 9 '16 at 4:48
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    \$\begingroup\$ You need a level converter. Since RX and TX lines on the micro controller operate at 5V while the wifi module works at 3.3V. you can make this work with a Level Converter Circuit. I can provide one on request. \$\endgroup\$ Feb 9 '16 at 5:21
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    \$\begingroup\$ @NaveenRaja Suggest you double-check that then - everything I've seen either says leave GPIO 0 open or pulled up for normal operation and pull down to flash. I've found my ESP-07 modules work best with it pulled up. In any case, all documentation says RST must be pulled up. If it's floating, it may have something to do with your problem so it's worth checking. \$\endgroup\$ Feb 9 '16 at 6:57
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    \$\begingroup\$ Naveen Raja, the Tx of the wifi module is an output @ 3.3v, that hitting the input of your 5v powered uC just means it will be only a little above sensing threshold, but doesn't likely explain the wifi module's overheating. If your problem is happening 'randomly' when starting the circuit, then sometimes gone after restart, I think @RogerRoland is on the right path. Probably a floating pin is setting an incorrect state in the module. Most ICs do not 'like' having their pons left completely floating. \$\endgroup\$ Feb 9 '16 at 7:18

Your micro controller runs at 5V and the WiFi module runs at 3.3V. The RX and TX lines also run at 5V and 3.3V respectively. To use the module in conjunction with the micro controller, you need a level converter which would convert 5V into a 3.3V signal.

To do so, you need to bare in mind that the serial lines (RX,TX) run at reasonably high frequency. For a basic application like this, you can get away with using general purpose transistors. For the circuit below, I have used two NPN transistors BC337.

enter image description here

When a micro controller pin is HIGH, Q1 turns on. Base of Q2 is pulled low, keeping Q2 switched off, therefore, Output is HIGH at 3.3V. Vice versa when micro controller pin is LOW.

This way a 5V signal can be shifted to 3.3V (or any other level).

Did a search on stack overflow, could not find anything close to this description to avoid any repetition. Hope this helps.

  • \$\begingroup\$ A single transistor in common-base configuration would be simpler and faster. \$\endgroup\$
    – CL.
    Feb 9 '16 at 7:59
  • \$\begingroup\$ @CL. could you provide the circuit? \$\endgroup\$
    – Honeybee
    Feb 9 '16 at 8:21
  • \$\begingroup\$ Single transistor level up shifter. (Downshifting does not even need a transistor.) \$\endgroup\$
    – CL.
    Feb 9 '16 at 8:50
  • \$\begingroup\$ While your converter is a useful circuit, and can be of use to OP, I'm not sure it anssers for what is czusing their circuit to sporadically overheat & cease normal function immediately after powering up. With that said; using the inverse of this circuit (step up) could improve signal transmission on the WiFi module Tx to uC Rx trace. Might want to add a protective (current-limiting) series resistor to the base of Q1 though. \$\endgroup\$ Feb 9 '16 at 13:44

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