The Embedded COMmunication Foundation Library (ECOM) is a generic communication library with abstract communication stream support (a communication framework only). It allows you to open and use streams on communication devices such as a COMM port.
This library also provides a device manager, including a generic device registry and a notification mechanism, which allows plug&play-based applications.
This library does not provide APIs to manipulate some specific options for each communication method, but it does provide some generic APIs which abstract the communication method. After the opening step, the MicroEJ Application can use every communications method (COMM, USB etc.) as generic communication in order to easily change the communication method if needed.
The diagram below shows the overall process to open a connection on a hardware device.
- Step 1 consists of opening a connection on a hardware device. The connection kind and its configuration are fixed by the String parameter of the method Connector.open(String).
- Step 2 consists of opening an InputStream on the connection. This stream allows the MicroEJ Application to access the “RX” feature of the hardware device.
- Step 3 consists of using the InputStream APIs to receive in the MicroEJ Application all hardware device data.
- Step 4 consists of opening an OutputStream on the connection. This stream allows the MicroEJ Application to access the “TX” feature of the hardware device.
- Step 5 consists of using the OutputStream APIs to transmit some data from the MicroEJ Application to the hardware device.
Note that steps 2 and 4 may be performed in parallel, and do not depend on each other.
Device Management API¶
A device is defined by implementing ej.ecom.Device. It is identified by a name and a descriptor (ej.ecom.HardwareDescriptor), which is composed of a set of MicroEJ properties. A device can be registered/unregistered in the ej.ecom.DeviceManager.
A device registration listener is defined by implementing ej.ecom.RegistrationListener. When a device is registered to or unregistered from the device manager, listeners registered for the device type are notified. The notification mechanism is done in a dedicated Java thread. The mechanism can be enabled or disabled (see Application Options).
ECOM Foundation Library is an additional library. In the platform configuration file, check Serial Communication > ECOM to install the library.
<dependency org="ej.api" name="ecom" rev="1.1.4"/>
This Foundation Library is always required when developing a MicroEJ Application which communicates with some external devices. It is automatically embedded as soon as a sub communication library is added in the classpath.