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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?

Robherc KV5ROB
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Honeybee
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  • 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. – KyranF Feb 09 '16 at 04:44
  • @KyranF yes i have connected a common ground between wifi and uC. The problem is occurring sometimes only. – Honeybee Feb 09 '16 at 04:48
  • Sounds like something is sinking current that shouldn't be. Have a schematic? – Krunal Desai Feb 09 '16 at 04:55
  • just so you know, chips can get quite hot (like, 100 celcius) and still be fine. Don't touch them though, as your finger will not like it. This can be normal operating temperature when doing a lot of work. So your perception of "its getting hot and now nothing is working" could be just a matter of "something is not working, but damn this chip feels hot perhaps that's the issue" when it might be fine. – KyranF Feb 09 '16 at 04:59
  • @KrunalDesai no i dont have any its simple system where i connect wifi to 3.3v and 5v to uC and a common ground between these two. and respective Rx and Tx – Honeybee Feb 09 '16 at 05:14
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    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. – David Norman Feb 09 '16 at 05:21
  • @DavidNorman Thanks for it! please provide me with the circuit – Honeybee Feb 09 '16 at 05:30
  • @NaveenRaja [The circuit](http://electronics.stackexchange.com/search?q=level+shifter) - it'll be in there somewhere. – Tom Carpenter Feb 09 '16 at 05:41
  • I think the 1K & 2K resistors formimg a 2/3 voltage divider should be dropping the uC's 5V signal to right at 3.3V, so I'm not sure that's the problem. I somewhat wonder, however, about the possibility of the mentioned problems being supply related. You mentioned having added a second supply to reduce the problem. Is your 3.3V regulator mounted to a sufficient heatsink, or might it still be overheating & not supplying enough power to the wifi module? – Robherc KV5ROB Feb 09 '16 at 06:01
  • @NaveenRaja, when you solve the problem, can you please post some feedback/comments as to how you solved it? – David Norman Feb 09 '16 at 06:15
  • @DavidNorman yes sure – Honeybee Feb 09 '16 at 06:18
  • @RobhercKV5ROB it happens at the initial state of working itself. So i think heat wont be a problem of increased current consumption. And Tx of wifi is connected directly this will affect the circuit right? – Honeybee Feb 09 '16 at 06:20
  • @NaveenRaja, I probably should have asked this to start with, but does the IC on the WiFi module get hot or were you referring to the voltage regulator? – David Norman Feb 09 '16 at 06:23
  • @DavidNorman yes the IC on wifi only is getting heated. Not the regulator. Usually wifi has considerable heat while functioning but the heat produced due to fault is extreme and no communication happens at that time. – Honeybee Feb 09 '16 at 06:27
  • @NaveenRaja When I use ESP8266, I keep RST and GPIO 0 pulled up to 3V3 too - I don't see how it works at all unless that schematic is missing those connections. – Roger Rowland Feb 09 '16 at 06:30
  • @RogerRowland gpio 0 will be high only when the module needs to be flashed with the firmware – Honeybee Feb 09 '16 at 06:46
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    @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. – Roger Rowland Feb 09 '16 at 06:57
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    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. – Robherc KV5ROB Feb 09 '16 at 07:18
  • @RobhercKV5ROB Yes, that's what I think - a floating reset pin is not going to do much good if it's oscillating on/off. – Roger Rowland Feb 09 '16 at 07:49

1 Answers1

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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.

David Norman
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  • A single transistor in common-base configuration would be simpler and faster. – CL. Feb 09 '16 at 07:59
  • @CL. could you provide the circuit? – Honeybee Feb 09 '16 at 08:21
  • [Single transistor level up shifter](http://electronics.stackexchange.com/q/82104/29811). (Downshifting does not even need a transistor.) – CL. Feb 09 '16 at 08:50
  • 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. – Robherc KV5ROB Feb 09 '16 at 13:44