[TriEmbed] ESP8266 Serial Connection

[Nathan Yinger]

Success! It did indeed need more power, and the tx pin on the ESP had to be
wired to the rx pin of the Sparkfun FTDI board, which is opposite of other
serial adapters I've seen.

For those interested, I got the 'AT OK' response with 9600 baud and NL + CR
line ending.

Thanks for the help,
~Nathan

On Tue, May 19, 2015 at 1:19 PM, Pete Soper via TriEmbed <
triembed at triembed.org> wrote:

>  This is nice information.
>
> I looked at it a bit and one thing that jumped out and swatted me on the
> nose is the fact that the radio board 3.3v power supply current draw can
> greatly exceed the current an FTDI chip can put out. The "usual" FTDI chips
> (and it appears Sparkfun is using a vanilla FT232RL) can only source about
> 50ma at 3.3 volts from their internal regulators. The ESP8266 board has
> typical (i.e. possibly far from "worst case") current requirements looking
> like this (from the table on the web site linked to below):
>
> 802.11b, CCK 1Mbps, POUT=+19.5dBm 215mA
> 802.11b, CCK 11Mbps, POUT=+18.5dBm197mA
> 802.11g, OFDM 54Mbps, POUT=+16dBm145mA
> 802.11n, MCS7, POUT =+14dBm135mA
> 802.11b, packet size of 1024 bytes, -80dBm60mA
> 802.11b, packet size of 1024 bytes, -70dBm60mA
> 802.11b, packet size of 1024 bytes, -65dBm62mA
> Standby0.9uA
> Deep sleep10mA
> Saving mode DTIM 1 1.2mA
> Saving mode DTIM 3 0.86mA
> Shutdown0.5uA
>
> So a lot of the time you're basically trying to kill the FTDI chip. I
> personally let the smoke out of one of these by accidentally telling it to
> try to supply a motor controller (off by an inch with the wire in the
> breadboard and hit the wrong power rail). They will die if tortured enough.
>
> So plan on the FTDI's 5v line driving an outboard 3.3v regulator with
> proper capacitors on both sides. An oscilloscope could confirm the radio is
> getting a proper supply and that it's not being yanked down by sudden
> changes in current demand.
>
> -Pete
>
>
>
> On 05/19/2015 11:00 AM, Christian Lilley via TriEmbed wrote:
>
> All of the information on the ESP8266 can be found here.
> <https://nurdspace.nl/ESP8266>
>
>  According to the wiki the baud rate should be 57600. Sparkfun does
> mention that a level shifter should be used and that it should not be
> connected directly to 5V sources.
>
>  Here is an example
> <http://allaboutee.com/2014/12/27/esp8266-arduino-code-and-circuit/>using
> the Arduino's software serial to communicate with the ESP and the normal
> serial lines to communicate with the FTDI board. This guy uses a 9600 baud
> rate but I don't know if that is a custom setting he uses.
>
>   Christian Lilley | Electrical Engineer
>
>  [image: images] <http://www.gomohu.com/>
>
> 919.794.8627 ext 129
>
> christian.lilley at gomohu.com
>
>  www.gomohu.com
>
>
> On Tue, May 19, 2015 at 10:44 AM, Nathan Yinger via TriEmbed <
> triembed at triembed.org> wrote:
>
>>    So, I have an ESP8266, a new serial adapter (
>> https://www.sparkfun.com/products/9873), and I'm trying to get them to
>> communicate.
>>
>>  When I power up the ESP8266, it creates a wifi network where I can join
>> and ping it, but as far as I can tell, reprogramming it requires a serial
>> connection.
>>
>>  When the ESP8266 is powered on, the 'tx' light on the serial adapter
>> flashes continuously, which I assume means the ESP8266 is transmitting
>> something. Nothing appears in my serial monitor though, not even gibberish.
>>
>> I'm using the serial monitor that comes with the Arduino IDE, with
>> various baud rates and line endings. I haven't found any documentation
>> about the byte length, parity, or character encoding used by ESP8266. I get
>> a TTYUSB device in /dev when I plug in the serial adapter, so it appears to
>> be doing something.
>>
>>  Does anyone know what's required to make the chips do something? Or have
>> a working setup they could bring to the next meeting?
>>
>>  Thanks,
>>  ~Nathan
>>
>> _______________________________________________
>> Triangle, NC Embedded Computing mailing list
>> TriEmbed at triembed.org
>> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
>> TriEmbed web site: http://TriEmbed.org
>>
>>
>
>
> _______________________________________________
> Triangle, NC Embedded Computing mailing listTriEmbed at triembed.orghttp://mail.triembed.org/mailman/listinfo/triembed_triembed.org
> TriEmbed web site: http://TriEmbed.org
>
>
>
> _______________________________________________
> Triangle, NC Embedded Computing mailing list
> TriEmbed at triembed.org
> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
> TriEmbed web site: http://TriEmbed.org
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.triembed.org/pipermail/triembed_triembed.org/attachments/20150519/3f1b31ce/attachment.htm>