ESP8266 Community Forum

- Sun Jan 10, 2016 12:52 pm #38430 Hi,
I've got some esp-01 module. I'm trying them out by terminal, by various libraries, etc.
First I've upgraded the firmware to AT 0.9.5.2 (it seemed to be stable). It worked, I was able to connect to wifi ap, etc.
And then I needed to change baud rate to 19200. I issued an AT+IPR=19200. I changed baud rate of terminal to 19200 and sent a simple AT. I got response OK. Well, at this point everything is okay.
Then I made an AT+RST. Module rebooted and from that point I wasn't able to communicate with it. I did a lot of tries at 19200 but nothing happened. Then - accidentally - I noticed that module sends some stuff at 115200 right after it gets power. The stuff looked like this (<...trash...> means a lot of random bytes):

<...trash...>MEM CHECK FAIL!!!

ets Jan 8 2013,rst cause:4, boot mode:(3,0)

wdt reset
load 0x40100000, len 816, room 16
tail 0
chksum 0x8d
load 0x3ffe8000, len 788, room 8
tail 12
chksum 0xcf
ho 0 tail 12 room 4
load 0x3ffe8314, len 288, room 12
tail 4
chksum 0xcf
csum 0xcf

2nd boot version : 1.2
SPI Speed : 40MHz
SPI Mode : QIO
SPI Flash Size : 4Mbit
jump to run user1

Fatal exception (0):
epc1=0x40201884, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000
Fatal exception (0):
epc1=0x40201884, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000
Fatal exception (0):
epc1=0x40201884, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000
....

Again, module worked well before changing baud!

With first module I thought this is a HW failure. But I can repeat all the above happening with another module....

Can anyone suggest some useful methods to get modules back to life?

- Sun Jan 10, 2016 3:06 pm #38438 I would think that a reflash would do the trick

pull IO0 to gnd
cycle power
flash it

I use ESP FLASH DOWNLOAD TOOL v2,4
of course you have to get a bin file somewhere...

- Sat Jan 23, 2016 7:51 am #39485 Thank you, re-flashing the devices brought them back to life.

But I can't change baud rate anyway. When I change baud rate to any value other than 115200 the same thing happens: module sends garbage and/or error messages. I've tried 0.9.5.2 and 1.1.1 AT fw.

Are you anyone out there who can change baud rate successfully by AT+IPR with 0.9.5.2 and 1.1.1 fw on esp-01??

- Sat Jan 23, 2016 9:10 am #39486 My experiance has been ... I change the baud then issue small delay to take affect,,,
The new baud will work until, RESET which goes back to the old baud rate,,,
By issuing the baud change early within the app, I miss the reset messages , but see the app messages...