I have a project where I want to run both an Arduino Pro Mini (the 3.3V version) and an ESP8266 on an FTDI breakout module (the kind that has a switch to flip between 3.3V and 5V). The project is pretty simple, nothing fancy (sending e-mail on a button press).
So:
From what I can gather the ESP8266 consumes about ~170mA, and I expect the Arduino to go for 30-50mA final.
The specs for the FTDI’s power handling are a bit fuzzier, mentioning “typical 100mA USB consumption” but “max 500mA as per USB spec”.
You think I can hook them both on the FTDI without “grilling” it?
When I power them “independantly” (i.e. powering the ESP8266 with the USB Power Supply and powering the Arduino Pro mini with the FTDI chip), everything works out great.
When I try to power both of them with the USB power supply, nothing gets off the ground. I got both my Arduino and the ESP8266 chip hooked on the + and the - of a breadboard. LEDs light up but something is amiss.
LexMajor:
Hi all, this is a great place to browse.
I have a project where I want to run both an Arduino Pro Mini (the 3.3V version) and an ESP8266 on an FTDI breakout module (the kind that has a switch to flip between 3.3V and 5V). The project is pretty simple, nothing fancy (sending e-mail on a button press).
From what I can gather the ESP8266 consumes about ~170mA, and I expect the Arduino to go for 30-50mA final.
The specs for the FTDI’s power handling are a bit fuzzier, mentioning “typical 100mA USB consumption” but “max 500mA as per USB spec”.
You think I can hook them both on the FTDI without “grilling” it?
If the switch is set to the 3.3v side, then the data signals take the voltage from the internal 3.3 voltage regulator (which can only sustain up to 50 ma) That is the purpose of the switch. If you power the ESP8266 from that 3.3 volt and when it really powers up (it’s Wifi-radio) then the 3.3 volt comes crashing down and both (ESP+ Arduino) end up getting in a reset state due to power failure. “Grilling” or not, it is not going to work for you so don’t try. The ESP8266 needs its own supply of 3.3 volt. Which could be some kind of low-drop voltage regulator module that itself is powered from the 5v USB pin (and GND). It depends on the design of the USB port that it is connected to if the 100ma limit is enforced. Not all manufacturers of motherboards do.
That would seem to do the job in terms of supply. Although, I don’t see what it has to do with USB. It has a barrel connector instead of a USB plug. According to the LM317 datasheet it needs on it’s input 3 volts above what is on the output. So you need to supply it with a DC-wallwart of 6.3 volt minimal. Can you confirm you have that?
When I power them “independantly” (i.e. powering the ESP8266 with the USB Power Supply and powering the Arduino Pro mini with the FTDI chip), everything works out great.
When I try to power both of them with the USB power supply, nothing gets off the ground. I got both my Arduino and the ESP8266 chip hooked on the + and the - of a breadboard. LEDs light up but something is amiss.
What am I missing here?
In order for the ESP8266 to work some of it’s GPIO pins need to be set in a certain state. Half way down the page of this link is the basic required wiring for the ESP8266 to get working: http://www.esp8266.com/wiki/doku.php?id … he-esp8266
p.s. Which pin of the Arduino board is connected to the 3.3 volt from that supply? Also, what should it be doing other than lighting up it’s power led? Does it work on it’s own if you have it programmed previously with i.e. the blink program? (try to avoid complex programming, or even communicate with the ESP. We need basic signs of life first. Just a heartbeat.)
To clear a few things upfront: I’m much farther along than the Blink program, wiring and all The whole setup is an “e-mail sending button”, and it’s working absolutely fantastic: the program compiles fine and sends e-mails like a charm (that onboard TCP stack really does the trick… ). Sharing the code if you’re interested
It’s powering them that’s the catch, and I’m stuck. I absolutely get what you’re saying for the “upfront voltage” of the LM317, and I suspect that’s what’s happening here… the Arduino seems to be in this weird “on off unstable cycle” (I see the LED13 blink in a semi-erratic pattern). datasheet for the LM317 says too little a difference voltage could cause a “drop out” (whatever that means). I really don’t know how to supply the right voltage for the power supply from the USB Barrel, though. (6.3V USB?!?)
I switched from a basic USB port to a wall wart capable of giving 5V and an assured 500mA, and what I’m planning to do is get the Arduino to start correctly THEN start the ESP8266 with a transistor (or opto-coupler), in the hopes it will interfere less with the Arduino program.
Think it will make any difference?
Oh, and to state the obvious: I really should have bought the ESP8266 “Thing”… that would have made my life tremendously easier
OK, I went ahead ahd did something…BAD. But read along.
One of the first thing I noticed is that the FTDI breakout board (indeed the one you mention)'s output, depite having the switch at 3.3V, is indeed 5V on the output pin. Also, the ESP8266 works like a CHARM when plugged into the FTDI breakout. So that got me thinking “OK, so it’s not optimal, but seems like the ESP8266 does tolerate 5V”.
So instead of using the 3.3V pins of the USB power, I plugged everything in 5V (Direct on the chip, in the RAW of my 3.3V Arduino Pro mini).
And it works. The electronics beginner in me has the impression of having made a pact with the devil.
So I’m inclined to say… so what? As long as it works OK. It’s not exactly expensive equipment, so I’ll replace if anything fries along the way… right? Right?
UPDATE: important note, although I am powering my ESP8266 at 5V, any I/O it has runs at my Pro Mini’s 3.3V. Same thing for my Arduino: nothing 5V is plugged into the GPIO pins.
OK, I worked something out, this should be the last post.
So, for some reason, powering my Arduino through the RAW pin at 5V, THEN powering my ESP8266 from the VCC pin of my Arduino works out very well. I’ve gathered from here and there that the Pro Mini’s regulator can give out ~200mA without too much of a problem, so assuming 50mA for the Arduino (that’s pessimistic), and I’ve measured the ESP8266 drawing 100-125mA, everything is working out very good both for the Arduino and the ESP.
I’ll probably never know why using the power supply at 3.3V to power both doesn’t work, but my “E-Mail sending Button” works really well, and every part gets a reasonable amount of power!
). Sharing the code if you’re interested 