6 years, 8 months ago.

Urgent! SWD error on mbed u-blox C027

After reprogramming mbed with a .bin image I started getting the "SWD ERROR" Now I'm not able to flash anything else. Some details: I have been reprogramming this board for over a month now, haven't had this kind of problem. I'm using the latest version for the CMSIS-DAP Interface Firmware; I have loaded the same firmware in a different board (another u-blox C027, I have 32 of these for a project) and got the same problem, now I have 2 defective boards.


Question relating to:

The u-blox-C027 is a complete starter kit that allows quick prototyping of a variety of applications for the Internet of Things. The application board has a MAX-M8Q GPS/GNSS receiver and …

Can you try pyOCD to test if the communication can be established? There are tests scripts like basic_test which you can run

posted by Martin Kojtal 10 Feb 2015

Thanks Martin, this sounds good, I'll try it as soon as possible.

posted by Marcio Menezes 10 Feb 2015

But ublox do not answer emails or give any support. I am thinking of going back to motorola products as they give good and proper support.

posted by Erastus Coetzee 10 Feb 2015

I'm actually a bit disappointed by the fact that mbed doesn't have a more efficient channel to support issues with their boards, which are quite nice and can in fact speed up development process, but without a direct support channel it makes me think twice before using it in the future.

posted by Marcio Menezes 12 Feb 2015

Martin I have tried to connect to my c027 with pyOCD however I keep getting a message like, unsupported device. Now I don't know if I missed something on the setup or if that means that my board is dead. Do you know any other way I could erase the LPC1768 memory? Do you think that I've got the device protected (like a JTAG fuse blow or similar)? Thank you for your support.

posted by Marcio Menezes 12 Feb 2015

3 Answers

6 years, 8 months ago.

Hi Marcio,

I had exactly the same. My unit was swopped and all are 100%. ( It was a new unit)

Hi Erastus,

you mean, mbed gave you a new unit?

posted by Marcio Menezes 12 Feb 2015
6 years, 8 months ago.

Dear Marcio,

Did you have any success on unbricking your C027? I've used pyOCD on mine and it presents the same issue you pointed.

No luck so far Helio... I think there is no way to recover these boards...

posted by Marcio Menezes 19 Feb 2015
6 years, 8 months ago.

Do you have an external power supply connected? The C027 only works with both USB and external power connected, without external power you'll see issues updating firmware, without USB you'll get random crashes in your application..

Andy thank you for your answer. I mentioned that I've been reprogramming the board for quite a while with no issues, so yes I'm using an external power supply, I have also switched to another one to make sure the first one had no issues, I have also monitored the power quality with an oscilloscope and checked the current drawn by C027 and it all seems to be fine.

posted by Marcio Menezes 10 Feb 2015


It was checked by the local supplier and it was faulty. I have the new unit plugged in on my dev board and it is working well.

I complied and down loaded the software no problem what so ever. My unit was new I only had it for a few days

posted by Erastus Coetzee 12 Feb 2015