EM203 Ethernet-to-Serial Module

The EM203 is an Ethernet module designed for onboard installation. It features one auto-MDIX* 10/100BaseT Ethernet port (please note that standard Ethernet magnetics are not integrated into the module), one CMOS-level serial port, and an internal processor whose firmware bridges the connection between Ethernet and the serial port.

The Ethernet “side” of the module connects to the RJ203 jack/magnetics module, a standard Ethernet magnetics circuit (e.g., YCL-PH163112), or an RJ45 connector with integrated magnetics. The serial “side” interfaces directly with the serial port pins of most microcontrollers, microprocessors, UARTs, etc. EM203 includes four onboard status LEDs.

* Auto-MDIX refers to automatic detection of “straight” and “cross” cables.

Key Features

The EM203 is an upgraded version of the EM203A module. It uses the newer DM9000B Ethernet controller, which supports auto-MDIX and features a fully digital PHY. The EM203 also has a lower profile, thanks to the replacement of two large vertical crystal oscillators (found on the EM203A) with smaller SMT components on the EM203.

Hardware and Functionality

From a hardware perspective, the EM203 serves as a universal platform suitable for a wide range of applications. The majority of its functionality comes from the application firmware, not the hardware itself. The EM203 is available with two distinct types of application firmware (version restrictions apply — see below):

• “Serial-to-Ethernet” firmware, currently in its 3rd generation ("Release 3"), turns the EM203 into a fully functional serial-to-Ethernet converter, allowing almost any serial device to connect to an Ethernet network. This firmware has a fixed functionality, but you can customize EM203's behavior by configuring its programmable parameters, referred to as settings, which are defined within the firmware.

• TiOS (Tibbo Operating System) firmware turns the EM203 into a Tibbo BASIC/C-programmable controller. When running TiOS, the EM203 has no pre-defined functionality, device behavior is entirely determined by your BASIC/C application. TiOS, BASIC and C programming are covered in the Development (TiOS) guide.

The newer DM9000B Ethernet controller requires firmware updates that were introduced in V3.70 of the “Serial-to-Ethernet” firmware and 2.05.10 of the “TiOS” firmware. Earlier firmware versions are incompatible with the EM203. If you require the older firmware, you will need to use EM203A instead.

The EM203 module includes a heat-conductive sticker. The protective paper must be removed before installing the module onto the host PCB. Refer to the Thermal Considerations section for more detailed instructions.