In the following pictures, the Esp8266's Rx is connected to the Uno's Rx.

garmisch_wong · March 17, 2018, 9:14am

In the following pictures, the Esp8266’s Rx is connected to the Uno’s Rx. Is this a mistake?
Secondly , the esp8266 uses 80mA, however, the uno only provide 20mA! Should I add a transistor in the 3.3v pin of the uno?

Marvin_Sielenkemper · March 17, 2018, 9:37am

the rxd and txd lines need to be crossed. txd is the sender (Talker) and needs to be connected to the Receiver at rxd

garmisch_wong · March 17, 2018, 9:38am

@Marvin_Sielenkemper so the above picture is wrong?

Marvin_Sielenkemper · March 17, 2018, 9:38am

yes

Marvin_Sielenkemper · March 17, 2018, 9:40am

and a transistor wouldn’t really help there, I’m afraid. what would you connect it to? It can not produce power which is not there.

garmisch_wong · March 17, 2018, 9:41am

I thought a transistor can amplify the current

Marvin_Sielenkemper · March 17, 2018, 9:46am

hm. but the current has to come from somewhere. the current a transistor draws on the emmiter depends on the current supplied on the basis. that is where the amplification happens. there is no magical multiplication of current…

garmisch_wong · March 17, 2018, 9:47am

So I should use a battery that can supply 80mA and add some resistor so it becomes 3.3v ?

Marvin_Sielenkemper · March 17, 2018, 9:50am

just a resistor would not work. the esp does not constantly draw 80mA. and if it uses less, the resistor would not lower the voltage enough which might damage the esp. you need a voltage regulator.

Marvin_Sielenkemper · March 17, 2018, 9:54am

how do you power the arduino?

garmisch_wong · March 17, 2018, 9:55am

With 4 AA batteries

garmisch_wong · March 17, 2018, 9:56am

And then I connect them to the jack on the Arduino

Marvin_Sielenkemper · March 17, 2018, 10:01am

so about 6v which is a bit on the low side…

garmisch_wong · March 17, 2018, 10:03am

Yea, I do realize that, but I haven’t found a battery box that holds more battery, so I will use 4 AA batteries for now.

Marvin_Sielenkemper · March 17, 2018, 10:28am

You could try something like that (emitter follower):

Marvin_Sielenkemper · March 17, 2018, 10:32am

So yes, just add a transistor: NPN, 500mW, 20V, beta of about 100 or more.

garmisch_wong · March 17, 2018, 10:32am

Ok, thank you

Zach_Hipps · March 17, 2018, 2:34pm

The Arduino’s GPIO pins can only supply 20mA of current. The esp8266 is connected to the Arduino’s 3.3V pin which can supply much more current. You’ll have to check the datasheet of the 3.3V regulator, but I think it’s somewhere around 200mA. You’re totally safe powering the esp8266 from the Arduino’s 3.3V pin.

As far as the UART goes, (Tx/Rx lines) if you’re trying to have the two devices talk to one another you need to have tx from one go to rx of other and vice versa. Hope this helps.

garmisch_wong · March 17, 2018, 2:42pm

I have done the connection right , and realize I it’s port is appearing in my mac , after some research, I know it’s because there isn’t enough current to power it. So is there any method of connecting the esp8266 with out a transistor?
Secondly, I couldn’t find the flasher for esp8266 for Mac, anyone found it?

Richard_Vowles · March 18, 2018, 5:29pm

I use esptool.py on the Mac. https://github.com/espressif/esptool