I am using a MOD-WIFI-ESP8266(REV.B) board with button to flash in UART mode. I was adviced by the Olimex document to flash firmware using the flash download tools. I flashed this firmware successfully, the document suggested that I flash the firmware at the time of writing the document, this is what I have done. But when I open Tera Term to test the AT command set, I am only getting an inflow of Junk values on my terminal. I have checked and rechecked and even tried other things, like exchanging Tx and Rx pin. Nothing is working, Please Help.
Did you try with different baud rate - try with 9600, then 57600 and 115200? Did you change the settings in TeraTerm as suggested at the bottom of the AT test document? Test with another terminal software, maybe the settings in TeraTerm are not proper by default. Try puTTy, for example.
Also can you show us a picture of the junk that you receive? There is some boot information in the beginning. After it try to type some AT commands.
Yes, I tried all Baud rates. The junk values are coming continuously. Whenever i interchange Rx and Tx, these junk values stop but I am unable to type in anything. I can send an image of how this looks like via email, if you could please share your email ID?
It looks to me as if the module restarts and sends boot messages again and again.
Can you confirm that the AT command firmware was successfully uploaded? Did you try to re-flash it? Maybe you got a small error in the firmware addresses (these should look exactly as shown on page 13 of the guide here: https://www.olimex.com/Products/IoT/_resources/ESP8266EX-how-to-update-firmware.pdf)
Yes sir, I re-flashed twice, succesfully. Still didn't make any difference. Also I'm unsure about the nature of these characters, whether they are the boot sequence or just junk. I have a screenshot, how do i share with you?
Upload it to a free image sharing site like imgur and give me the link.
Well, did you try to type "AT"? The initial boot information might throw garbage characters like this because it has different baud rate requirement compared to the baud of the application (in this case the AT firmware). The native bootloader is made with 40Mhz quartz in mind and the board has 26Mhz. You might also try 74880 baud but it is not clear if it would fix the issue. Check here about the different boot and application baud rates: also: https://stackoverflow.com/questions/40708356/why-do-i-need-to-change-the-baudrate-after-i-send-a-reset-to-the-esp8266
Can you also upload a picture of the window of ESP FLASH DOWNLOAD TOOLS when you upload the firmware, maybe I can spot something?
This is when I flash it. And also, I'm unable to type any AT commands and changing the Baud rate just makes the junk move faster or slower.
Also, I'm using the following hardware:
Silicon Labs UART bridge with 3.3v, Tx, Rx, GND pins connected to my MOD-WIFI board.
Tx of UART bridge ---> Rx of Module (On the UEXT connector)
Rx of UART bridge --> Tx of Module(Also on the UEXT connector)
That may well not provide enough power. (And then you'd have a mess.)
The rest is alright and the fact that you can upload the firmware is actually a fairly good indication that the hardware is alright. Meanwhile I tested the guide again here and it all works well so it is not an issue in the guide. Did you change the settings of teraterm: "In the "New-line" box change the value for the "Transmit" field to "CR+LF"."?? Then test "AT" command again.
Yep, I have followed all the instructions on the manual exactly right. I did change the transmit to 'CR+LF'. I'm unable to type any AT commands because as soon as I open the serial port, I'm just not able to type. I even left the junk for nearly 10 minutes and It still doesn't stop. I have no clue what to do next. Do you recommend I change the Tx & Rx from the UEXT connector and use some GPIO pins instead?
First test if the TX of your adapter is alright - disconnect it from the MOD board and connect RX and TX together (with a wire maybe) and check if you can send text over the COM, there should be echo returned.
Then as JohnS suggested it might be something related to the power supply, maybe it can't provide sufficient current and the board stays keeps resting when more current is required. If possible try to provide 3.3V from another power source.
But it also can be more serious issue with the cable - for example if RX and TX levels are not 3.3V levels (sometimes these are as high as 4.2V or 5V). I recommend you to test with another serial cable if possible.
I tried the following:
1. Replaced the UART bridge with a new one with a different cable. It made no difference.
2. Replaced tera term with puTTY. Same thing as tera term happened, i got continuous junk values.
3. Shorted Rx & Tx of my UART bridge and sent messages using Qcom and got echo : https://imgur.com/a/qNOeaxr
4. Checked the voltage received by the 3.3V pin of the MOD-Wifi board and got 3.34V.
5. Re-dumped the standard firmware and tried again to no avail.
6. Changed Rx and Tx to pin numbers 3 & 5 instead of the Rx and Tx of UEXT connector.
None of it worked. Getting the same result.
Drop us an e-mail at firstname.lastname@example.org and Tsvetan would handle the warranty and returns. Make sure to link to this thread so we don't waste time :)