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Forum Index : Microcontroller and PC projects : ESP8266 and TeraTerm problem

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Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 192
Posted: 04:45pm 22 Jan 2015
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Hi all,

I went out on a slight limb and purchased a pair of ESP8266 boards with the external aerials hoping for better range out of them.

I now have one working but have a strange problem; some characters are not being displayed correctly in Tera Term (TT).




WHILE the log from TT shows :-

AT

OK
AT+RST

OK
ö,"
YâG@ÇR búbc8$ýbº÷
[Vendor:www.ai-thinker.com Version:0.9.2.4]

ready
AT+CWLAP
+CWLAP:(3,"AndroidAP",-38,"78:4b:87:5b:6b:d7",11)
+CWLAP:(3,"BobNet2",-60,"08:bd:43:4b:1b:e5",11)

OK

As you will see still some junk in the log BUT "better" than the screen!

Any thoughts?

Rob
Rob White
 
Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9586
Posted: 12:17am 23 Jan 2015
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Hi-de-hi.

I am guessing that you are using auto-detect for setting the baud-rate, by just sending "AT" and <CR>. The module locks onto that, and sets the baud-rate.

I have had very limited success with that method, and plenty of modules support it.
I always prefer to set the baud-rate to a known speed, then you can rule out any kind of auto-baud mishaps which may(or may not) be taking place.

AT+RST sounds like a system reset command, and if that is the case, it is likely that this will reset the default baud rate too.

Ignoring that rubbish text for the moment, is the module OK from that point on, or does it intermittently keep coming up with the rubbish text?
Smoke makes things work. When the smoke gets out, it stops!
 
Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 192
Posted: 11:14am 23 Jan 2015
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No the module seems OK from then on. I have managed to set it up as a webserver as per Geoff's SC article.

BUT

Have now lost comms with the module completely!! Even my second one does not want to communicate with me!
Rob White
 
Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3282
Posted: 01:05pm 23 Jan 2015
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I lost a couple of modules by still driving the Rx line while the module was powered down. This is why the article suggests using a series resistor.

Geoff
Geoff Graham - http://geoffg.net
 
Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 192
Posted: 07:20pm 24 Jan 2015
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Geoff,

What was the exact state of the EPS's that you destroyed? Did they transmit rubbish with some characters OK. I get the word "ready" but all else is garbage and I cannot see any characters I send to it.

I have the "33K" resistor in series. Interestingly I can not get a loop back to work through the resistor (resistor is actually 3 10K resistors) loop back works only with 10k in series. I am using a freetronics USB to serial adapter with switch set to 3.3v DVM verifies this. With this setup it is not possible to power down the RX line.

A question about your SC article are the pin numbers correct in Fig4? (MM user manual Ver 4.5 page 5 shows COM1 on pins 21 & 22).

Rob

Rob White
 
Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3282
Posted: 12:20am 25 Jan 2015
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They just stopped communication and appeared to be totally dead. The ESP seems very fragile so maybe (in your case) the 33K resistor was not enough. In later code I closed the serial port which put Tx into high impedance before I powered down the ESP so I did not extensively test the 33K option.

The pin numbers are wrong in the SC article. The Micromite manual is correct. One of the problems with a magazine article is that you cannot go back and correct errors as you can with a web page

Geoff
Geoff Graham - http://geoffg.net
 
Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 192
Posted: 09:23am 25 Jan 2015
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Thanks Geoff,

I think I will shelve my testing until I get some more MMites so I can power all from the same supply and also use the power down technique.

Rob
Rob White
 
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