AT+WDWL firmware update hangs near the end

I tried to upload firmware for SL808xT using at+wdwl when it hangs just before transferring the entire file. :frowning:

After that, I’m no longer able to access Open AT commands but I’m still able to call at+wdwl.

Pls help me.


How big a jump in firmware are you trying to upgrade from/to?

I have personal experience with the Q26 modules when upgrading from R7.47 to R7.52 that you can’t directly upgrade. I needed to go R7.47 -> R7.50 -> R7.52.

As I understand, the Q26 are similar to the SL80x series modules, so if you are doing a similar (large) update, then you may need to do the same.

Ciao, Dave

Hi Davidc, thank you for replying. I’m upgrading from R7.50 to R7.52. I’m not familiar with the CPU, is it possible that it ran out of space or the upgrade failed?


I would have a very close read of the release notes to see if there any issues or requirements for the upgrade. In particular, I would look to see if you need to resize the AD flash area to fit the new flash binary image into.

You might have to go to 7.51 as part of the upgrade process.

I would also download a clean version of the firmware from the Developer Zone in case the version you are using is corrupt.

We’ll get there…

Ciao, Dave

Have you deleted the OAT app before upgrade?
See the note under section 5.3 of 7.52 release notes (

I remembered issuing at+wopen=3 and 4 but I can’t confirm if it went through. If the app is not deleted, what can be done? :frowning:

Oops… didn’t read the whole thread. Actually, deleting of OAT app is more applicable to the Dave’s issue of upgrading from 7.4x to 7.5x firmwares for 2G modules than your issue.
For SL808xT, 3 points:

  1. Use different tools. Teraterm doesn’t work for me. ClearTerminal & Developer Studio work fine for me.
  2. Use USB instead of UART. It is quicker and seems to be more reliable.
  3. Download firmware before bootloader as mentioned in release notes. If it fails use firmware exe file.

The exe file is more reliable for firmware upgrade & module recovery than xmodem. I would equate the usage of exe file on SL808xT to using DWLWin based firmware upgrade on 2G modules (in case you are familiar with DWLWin tool).

Hi Sushil, thanks. I’m using Hyperterminal. I managed to find another PC with a serial port and this time the upload was successful using the same hyperterminal software. It appears to be hardware imcompatibility?


What serial port were you using? Was it a ‘hard’ serial port (i.e a D9 connector on the PC) or a USB to RS232 adapter?

I’ve had problems with the early prolific brand adapters - from what I’ve learnt recently I suspect that some of them used clone chips. I now only use FTDI brand adapters (as produced by FTDI, not just branded FTDI) and no longer have many problems with usb to serial adapters.

Also, did you have all 9 wires connected in the serial cable? The PTS recomends that the xmodem firmware download needs hardware flow control.

Anyway, good that you’ve got it working.

Ciao, Dave

Is that a regression :question:

XMODEM shouldn’t need flow control; it should be self-pacing. But early Q26s (and WMPs?) had a silly implementation which would do a Flash write in the middle of an XMODEM block - so they needed hardware flow control. But I thought that had been fixed?!


For both PCs (first one failed, second one was successful), I used the hard serial port COM1. Initially, I thought of using an ATEN serial-usb adapter that I had - not sure if that is using prolific or FTDI but decided not to for fear of bricking my modem. :open_mouth:

I used hardware flow control and 1K XMODEM.