My problem is related to SIM800 connection messages.
I use the module with STM32 developlment board. Sometimes module is reporting SMS Ready and Call Ready messages respectively. When I start to send AT commands to the module, it may send these messages (it doesn't happens all the times).
However, the commands I previously sent are apparently unrelated (for example HTTP commands), and SMS Ready / Call Ready messages is coming while they are not expected.
Because of this reason, Keil is reporting "Can not access" message in the debug session. Is it possible that disabling these messages when the connection is established? Or it means that module has an unexpected reset?
According to SIM800x modules AT commands guide, SMS ready and Call ready are URCs (unsolicited result codes) sent at startup as soon as the capabilities to deal with SMS and to perform calls respectively are correctly initialized and available.
So this is the first bad news for you: if you see them it probably means that your device reset due to a bug or as a consequence of one of the commands you previously provided.
The second bad news is that on the AT command guide linked above there's no mention of the capability to disable SMS Ready URC.
There's fortunately at least a good news: Call ready can be disabled by means of AT+CIURC command:
AT+CIURC (Enable or Disable Initial URC Presentation)
Syntax: AT+CIURC=<mode>
<mode> : 0 Disable URC presentation - 1 Enable URC presentation
Note: When module is powered on and initialization procedure is over URC "Call Ready" will be presented if is 1.
The guide also mentions the fact that this setting is saved in the profile area. So, in order to make sure it is persistent to reboot, after issuing the command store active profile:
AT&W
OK