Meaning of APP RDY in BG96 module


i am a developer of a IOT-Device which uses the BG96 modules.
I have two BG96 modules, on which i did some minor configuration changes (apn, RAT etc.). Registering to mobile network and TCP/IP connections are working, but i wonder about the meaning of the APP RDY message. One of the module do send this message after startup. The other doesn’t send that message, but is still working properly.

My first thought was SIM card, but i receive APP RDY even if no SIM card is installed.
I didn’t find anything in the AT and TCP/IP-manuals, neither didn’t find anything helpul in internet searches.

I want to correctly handle the bootup messages to prevent any pitfalls in the future.

Thanks and best regards

AP ready is a very important message , You know , There are 3 CPU cores in the module , All the peripherals and the user interfacs are loaded on AP core.

if you get AP ready , it means that AP OS run up , and ready to be operated
if not , it means something is wrong about AP core OS.

Thank you Steven, but that doesn’t answer my questions.

I have one module, that responds with RDY and APP RDY almost immediately after power on. The other module responds with RDY after activating, but i have discovered that the APP RDY message ist sent much later. I can send a few commands and get their responses and then receive the APP RDY message between commands.

The module responds to AT commands already, before it sends APP RDY.

So what’s up with that message? Do i have to wait for it, before doing anything else? Or can it be ignored?

What can be the cause, that these modules behave differently from each other?

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I used to wait for APP RDY and generate an error if APP RDY was not received within a couple seconds.

But this approach frequently created false errors. I had situations that after the power up function, which waited for Status pin, the APP RDY message came too quickly and the UART hardware (NXP UART with SPI) was not initialized yet and I would not get the interrupt signaling the character receive with the APP RDY.

Now, I wait for APP RDY or timeout at about 2.5 seconds and proceed to operate the modem. So if I catch the APP RDY it just speeds up the power up sequence. The next part of my driver’s init sends the necessary AT commands for expected behaviors. It these init cmds fail then I throw an error.