Solution: Teensy 3.2 and SIM808: Can't connect to APN!


I just spend a day on a annoying problem.

I had a code that was working with a Arduino Due and a SIM808 GSM modul, using THINGER_TINY_GSM libary.

I compiled the code for a teensy LC and it worked right out of the box.

Then I switched to a Teensy 3.2 and nothing was working. The debug out put stoped at “Can’t connect to APN!”

After checking powersupply, changing GSM Modul etc, I noticed a option in the arduino IDE when the teensy drivers are installed: Their are optimization settings for the code: fast, faster, fastest, debug and smallest code.

I never touched this settings and it was set to “faster”. When I changed it to debug everything worked. Later I checked if it also works for the other settings and noticed that I only experienced the problem with the standart settings “faster”.

Perhaps this post will save somebody one day!

But nevertheless I still love this thinger project.


Nice! Thanks for the info! Do you have any clue why in the “FASTER” setup it did not work?

Just for curiosity… What are you working on using GPRS devices?