Last week, I bought a pair of M8N GPS receivers. They seem genuine, the picture seems to correspond with genuine examples on the internet and flashing a firmware does seem to work. It came with firmware 3.01, however, I want to downgrade the software to 2.01 in order to use it with rtklib.
When I flash the 2.01 software from u-blox.com with u-center 8.25, the uploading seems to succeed. Here is a log where I just tried to downgrade the module:
However, after uploading, the version still seems to be 3.01. Here's a screenshot of u-center. As you can see, both the 'Software version' and 'extension' boxes show software version 3.01.
Today, I tried an older version as well, u-blox 8.20. I also tried an old FIS file, extracted from u-center 8.16. This all doesn't seem to make a difference, the board keeps running 3.01.
Is it possible that the hardware prefers loading its ROM? If so, can I 'tell' the module to boot from flash? There are people on fora telling that they successfully downgraded their M8N receivers, but I don't seem to be able to do just that. Does anyone here know how it's done?
Your help is appreciated!