ESP8266 Community Forum

- Mon Oct 05, 2015 10:43 am #30550 hello guys !
I'm new to your forum and usually try to solve questions by myself and the help of existing information but this time i totally rely on you

when i communicate to my ESP-03 characters received from the device are sometimes scrambled but the error is always an invalid Bit-3. I have already soldered an additional capacitor as i thought it could relate to the power supplied but the problem persists.

When i reset the device it responds:
▒rl▒B▒
Ai-Thinker Tekhnology(Co. Ltd.

realy

or similar. You see the 'c' 0x63 0b0110011 becomes a 'k' 0x6B 0b0110111 ,
the 'd' 0b01100100 becomes an 'l' 0b01101100 .....

The response to the rest-command reads:
AT version: 0.21.0.8
SDK version: 0.9.5

SPI speed: 40 MHz
SPI mode: QIO
Flash Size 4MBit

Has anyone of you got an explanation why Bit-3 shows up erroneously ?
I guess this is also the reason why i'm not able to flash the unit .....

Thank you in advance
Tom

Attachments

my ESP-03 with UART communication problems ....

- Mon Oct 05, 2015 3:23 pm #30587 Hi, if you are only using power from a usb via the USB TTL, thats most likly your problem the ESP is very hungry at times. The cap may stop the voltage dropping enough to crash but can still mess with the logic levels on both the ESP & the USB to TTL.

- Mon Oct 05, 2015 4:46 pm #30601 Hi Bear !
Thanks for your answer.
But i'm using a dedicated 3.3V regulator that is powered directly from the USB-connector and should be able to sink 800mA. The smd-caps are located at the regulators input and output and the 220uF cap is directly soldered to the supply pins of the ESP-module.
And how could a bad supply only affect Bit 3 being set - never ever any other bit !

Sometimes "Ai-Thinker" becomes "Ii-Thinker" so even the very first byte sent is sometimes affected in this way ...

I wanted to use the module with an stm32 application and also develop stand-alone software with Eclipse once in a while.

Any other ideas ?

- Mon Oct 05, 2015 5:27 pm #30607

Any other ideas ?

The only time I encountered junk characters was at first, when my homemade RS-232 to TTL converter had a wiring fault.

So this makes me think there's some issue with your FTDI adaptor. Two things to try:
- the FTDI adaptor runs from the USB's 5v. Move the 220 uf to the 5v terminals of the FTDI adaptor, add something like a 10 uf tantalum on the 3.3 in on the ESP.
- try an external source of 3.3v on the ESP. As mentioned, USB power to ESP has sometimes caused problems