Aleksander Morgado
4f9817741f
The default AT commands to play with SMS rely on AT+CPMS to select the default memory storages for different operations. AT+CPMS defines 3 different storages, called 'mem1' (for reading/listing/deleting), 'mem2' (for storing or sending from storage) and 'mem3' (for receiving). For example, when an SMS is to be deleted, we first need to select with AT+CPMS the proper 'mem1' storage before issuing the command to delete the SMS part. But, in order to do this properly we need to synchronize the access to the currently set storages, so that no more than one action is run in the storages at the same time (e.g. don't store an SMS while another SMS is being deleted). In order to synchronize this access, we now provide commands to lock()/unlock() the storages, which should be used when we want to do some operation on them. Note that this logic is only required because we cannot specify the storage explicitly in the specific AT command operations. With QMI we don't need this locking/unlocking.
ModemManager. The problem ModemManager tries to solve is to provide a unified high level API for communicating with (mobile broadband) modems. While the basic commands are standardized, the more advanced operations (like signal quality monitoring while connected) varies a lot. Using. ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides DBus API, it is possible to use 'dbus-send' command to control it from the terminal. There's an example program (tests/mm-test.py) that demonstrates the basic API usage. Implementation. ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C. The devices are queried from udev and automatically updated based on hardware events. There's a GInterface (MMModem) that defines the modem interface and any device specific implementation must implement it. There are two generic MMModem implementations to support the basic operations (one for GSM, one for CDMA,) which are common for all cards. Plugins. Plugins are loaded on startup, and must implement the MMPlugin interface. It consists of a couple of methods which tell the daemon whether the plugin supports a port and to create custom MMModem implementations. It most likely makes sense to derive custom modem implementations from one of the generic classes and just add (or override) operations which are not standard. There's a fully working plugin in the plugins/ directory for Huawei cards that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! API. The API is open for changes, so if you're writing a plugin and need to add or change some public method, feel free to suggest it!