WS6318 TX burst indication issue

Good day!

In our project we send data from UDP-client (running on WS6318) to UDP-server 1 message per 2 seconds.
Usually it works ok and I see that TX_CTRL LED blinks normally during Tx burst. TX_CTRL LED is connected according to datasheet.

The question is as follows. What might be the reason that cause TX_CTRL LED stop blinking for a while and start blink normally.

Assume that there is no bugs in software. My idea is that it might be result of bad GSM signal level. Am I right and what else could impact on TX_CTRL LED?

Thank you beforehand.

Best regards,


Is that avalid assumption :question:

Thank you for your answer.

Well, let’s exclude the reason of bugs in software of our MCU (we use MCU to control WS6318).
How does WS6318 behave when it is already in continuous mode, transmit data and suddenly the signal level become low? Is it waiting for a better conditions to start Tx burst again?

Now it operates in the following way:

  1. It works properly (TX CTRL blinks 1 time per 2 seconds)
  2. Then it stop blinking normally. Sometimes it blinks but less brighter than usually.
  3. Then it starts blink normally

Best regards,

Good day!

To exclude the reason of possible software bugs in MCU software I use the auxiliary LED. The auxiliary LED is switched on when I really call the transmit function (this function transmit a message from UDP-client to UDP-server 1 time per 2 seconds). TX_CTRL LED is still connected according to the datasheet and is controlled by WS6318 itself.

What I see:

  1. Normally TX_CTRL LED and auxiliary LED blink 1 time per 2 seconds
  2. Then TX_CTRL LED stops blinking but auxiliary LED continues blinking normally.
  3. Eventually 2 LEDs blink synchronously.

What might be the reason of that TX_CTRL LED strange work? The bad signal level?

Best regards,

Good day!

To determine the signal level I use AT+CSQ command.
The WS6318 returns
+CSQ: 0,99

0 is usual, 10 is rare, 20 is very rare, 30 is extremely rare.

What is strange:

  1. Why the distance between numbers are equal to 10?
  2. Can a bad antenna connection result in these responses?

Best regards,


May be some different in CSQ report it is result of GSM network configuration and loading. Your modem will seek nearest free base station for data exchange. You can check it by run the command:

+CREG: 2,1,"XXXX","YYYY"

The same base station registration codes correspond to equal CSQ levels if your device not moving across. The CSQ level usually flow around 2-3 points. Modem need to select another base station by GSM network rules…

About TX-LED blinking mode it is very unstable parameter while your MCU transmit data. For example, length of UDP/TCP packets will vary depend on current operator settings. In case of DNS names using, our application need to resolve name to IP-address first but this information will be cashed once (so next session has different time to transmit).

Next possible condition in retry transmission for error recovery or completely fail to transmit data on radio link protocol level at the selected channel/timeslot.

If you want to get more information, you will make a log of your MCU transmissions and receptions time/size and compare the records. Also you will compare traffic volume by GSM-operator billing system report and blinking intensity for some period.

The GSM network is unpredictable time to time… We have to use GSM-CSD connections for data files exchange mobile-to-mobile. Usually a file of fixed volume will send at fixed bitrate 9600 and real speed 800-1000 bytes per second but sometime (at the middle of transmission!) real speed grow up to 2000 bps or more and file transferred for ~4 minutes not for 10! I have to check result! No errors, file transferred - OK. All possible modem tuning parameters will used and applayed automatically the same manner every time but I can not to repeat this situation next time. It work? Good!

Best regards,

Good evening!

Vlad, thank you for your huge answer.

Strangely enough but it was a error in the software.
The reason of this error is my misunderstanding of WS6318 datasheet.
I read not official and not latest version.

Now it works ok.
At the very beginning AT+CSQ returns 0, then 10 and eventually it gives me something close to 31.
I don’t know for sure whether WS6318 should behave the same way.
Does anybody know?

Thank you.

Best regards,