API functions often allow application to set blocking parameter indicating if function shall be blocking or non-blocking.
When the function is called in blocking mode blocking = 1, application thread gets suspended until response from GSM device is received. If there is a queue of multiple commands, thread may wait a while before receiving data.
When API function returns, application has valid response data and can react immediately.
- Linear programming model may be used
- Application may use multiple threads for real-time execution to prevent system stalling when running function call
Warning
Due to internal architecture, it is not allowed to call API functions in blocking mode from events or callbacks. Any attempt to do so will result in function returning error.
Example code:
../examples_src/command_blocking.c
If the API function is called in non-blocking mode, function will return immediately with status indicating if command request has been successfully sent to internal command queue. Response has to be processed in event callback function.
Warning
Due to internal architecture, it is only allowed to call API functions in non-blocking mode from events or callbacks. Any attempt to do so will result in function returning error.
Example code:
../examples_src/command_nonblocking.c
Warning
When using non-blocking API calls, do not use local variables as parameter. This may introduce undefined behavior and memory corruption if application function returns before command is executed.
Example of a bad code:
../examples_src/command_nonblocking_bad.c