Bios Default BAUD [esp8266]

KevinA
Posts: 12
Joined: Tue Sep 20, 2016 3:09 pm

Bios Default BAUD [esp8266]

Postby KevinA » Sun Oct 02, 2016 9:26 pm

While working on the latest SDK I was trying to figure out the garbage on my screen every time I rebooted to discover 74880 baud would allow me to see what was being dumped to the screen. Is there a reason for 74880 instead of a standard baud rates? Some terminal programs do not have 74880 support and there are plenty of posts about garbage at the esp8266 forum.

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kolban
Posts: 1683
Joined: Mon Nov 16, 2015 4:43 pm
Location: Texas, USA

Re: Bios Default BAUD

Postby kolban » Sun Oct 02, 2016 10:20 pm

I am finding that my default baud rate after a reboot is 115200. I am using the latest ESP-IDF images from Github and am using a DevKitC board made by Espressif to host my ESP32. Now ... I am also flashing the device at 115200. When I tried to flash it with a faster rate ... i.e 230400 that worked ... however on reboot, I found that at the initial start of a soft reboot, the speed remained at 230400 until somewhere into the boot process where it seemed to switch back to 115200. So far, I haven't seen a 74880 on my ESP32 travels.
Free book on ESP32 available here: https://leanpub.com/kolban-ESP32

a2retro
Posts: 56
Joined: Tue Dec 01, 2015 3:09 am

Re: Bios Default BAUD

Postby a2retro » Mon Oct 03, 2016 3:01 pm

I find 921,600 with compressed works quite nicely for me using my Particle Programmer board. I have not tried that speed via the built in silabs interface yet.

Edit: 921,600 also works for me on the silabs interface

KevinA
Posts: 12
Joined: Tue Sep 20, 2016 3:09 pm

Re: Bios Default BAUD

Postby KevinA » Tue Oct 18, 2016 5:59 am

My bad, I should have posted in the esp8266 forum, the latest NodeMCU from LoLin has sdk 5.2 on it and this is what it does:

print(uart.setup(0, 74880, 8, 0, 1, 1 ))

ERROR

Communication with MCU..Got answer! Communication with MCU established.
AutoDetect firmware...

Can't autodetect firmware, because proper answer not received (may be unknown firmware).
Please, reset module or continue.
boot mode:(3,6)

load 0x40100000, len 1856, room 16
tail 0
chksum 0x63
load 0x3ffe8000, len 776, room 8
tail 0
chksum 0x02
load 0x3ffe8310, len 552, room 8
tail 0
chksum 0x79
csum 0x79

2nd boot version : 1.5
SPI Speed : 40MHz
SPI Mode : DIO
SPI Flash Size & Map: 8Mbit(512KB+512KB)
jump to run user1 @ 1000

È[ƒÐÚ�R+­¨R�
After I can switch to 115200 and read everything.
AT+GMR

AT version:0.60.0.0(Jan 29 2016 15:10:17)
SDK version:1.5.2(7eee54f4)
Ai-Thinker Technology Co. Ltd.
May 5 2016 17:30:30
OK

But I haven't gotten my ESP3212 boards yet, still waiting..

ESP_Angus
Posts: 2186
Joined: Sun May 08, 2016 4:11 am

Re: Bios Default BAUD [esp8266]

Postby ESP_Angus » Tue Oct 18, 2016 10:42 pm

Thanks for updating Kevin. The 74880 on esp8266 is an artifact of the crystal speed (if you use a 40MHz crystal the baud rate is 115200, but everyone uses 26MHz crystals so it's proportionally lower.) On ESP32 the default baud rate is 115200 regardless of crystal clock rate.

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