Just resolved a nasty timing issue regarding AT-commands and serial auto-baud config on our SIM7070 NB-IoT module. Phew! 😅

The MB-IoT module talks to our system via a serial interface using AT commands. Our PPP daemon for the mobile data connection needs to send various AT commands (using ChatScript), but communication didn't work in the first place.

Well - it worked when using the serial-to-USB converter, but it did not work via the native serial connection. The datasheet mentions that by default "auto-baud" is enabled, which tries to configure the module's baud rate by detecting a predefined bit sequence. That is why we need to send an "AT" before we issue any more AT commands. We do that - but probably we're too fast sending the next AT command, because if we introduce a bit of delay by sending another "AT", everything works fine. 🥳

Probably the serial-to-usb converter introduces just enough delay to make it work properly. 🤔

#iot #nbIoT #ppp #raspi #simcom #mobileNetwork

Let’s put #cellular #IoT to the test!

Sharing performance metrics of SIMCom's LTE Cat-M1 and Cat 1 modules with Monogoto core network - allowing you to make a better decision on what technology to use.

#SIM7000E #A7672E #SIMCom #monogoto #LTE #IoT

https://monogoto.io/2022/12/22/the-true-speed-of-cellular-iot/