originally I was able to send measurement data through a SIM800L to my database on my Raspberry Pi.
The new infrastructure I have to use only has TLS1.2 and TLS1.3 enabled, which makes the SIM800L obsolete for me: SIM800L and old Firmware
Now I'm looking for breakouts/shields, which I can connect to my Arduino Mega2560 and already have at least an embedded TLS v1.2.
Originally, I had my eyes on this shield from sparkfun: SparkFun LTE CAT M1/NB-IoT Shield - SARA-R4, but from the video their version has 00 at the end, which means according to the datasheet for the SARA-R4 modules doesn't have embedded TLS 1.2. They are using SARA-R410M-02B-00, but only the SARA-R410M-02B-01 and onwards already have it embedded as far as I understood (Page 9).
Does anybody already have experience with cellular modules for the arduino, which are capable to do handshakes with servers out of the box, because they already have embedded TLS 1.2? It's really hard to find any references or projects, where somebody uses a shield or breakout to send data via cellular networks to a webserver, which only works with TLS v1.2 or TLS v1.3 in my experience.
PS. I've sent Sparkfun an e-mail to ask them, if this shield uses u-blox-modules, which have no embedded TLS 1.2. I will post it here, if they confirm it.
Kind regards,
SciWax
Modules found so far, which meet the named requirements:
GPy by Pycom (LTE-M with 1nce Simcard --> 1nce Simcards not available for private persons)
I've received an answer from Sparkfun. All of their LTE CAT M1/NB-IoT - SARA-R4 shields have a "00" at the end, which implies that they don't have TLS 1.2 embedded.
Thank you for reaching out to us. Unfortunately, all of our modules confirm that they are "02B-00".
I'm using the GPy from Pycom at the moment. The GPy has embedded TLS 1.2 and I've managed to send my data to a mysql mariadb database via WiFi so far. I just used serial communication between my Arduino and the GPy to transmit a json-formatted string to the GPy, which does a POST-Request. The GPy supports LTE CAT-M1 and NB IoT. I've ordered a LTE-M Sim card to test sending data through a LTE-M cellular network. Supposedly the best thing about the GPy is the power consumption during data transmissions using a cellular network. It's less than 500 mA, when I interpret the datasheet of the GPy correctly. The SIM800L can have a peak power consumption of 2A during transmissions.
A little update after trying to make the data transmission via LTE-M work with the GPy for 1.5 months.
Transmitting data via LTE-M in Germany works with the GPy too and an 1nce Prepaid Simcard, but the modem firmware on the GPy is really unstable at the moment. An Arduino has to be used as a Watchdog, so in the case the GPy freezes because of the modem firmware, the Arduino can set the Reset Pin on the GPy LOW. The health of the GPy (or any other Pycom MCU) is easily checkable, if you toggle one of the GPIO Pins of the GPy programmatically and let the Arduino listen to the Pin. If the Pycom device freezes, the Arduino will recognize, that for a certain time the GPy pin wasn't toggled from HIGH to LOW or vice versa.