Serial to Ethernet Converter for TM4C129x Microcontrollers Using RTOS

Some legacy products may only contain a serial port and accessing such products is increasingly becoming a challenge due to the inability to add multiple such products to a shared network and the inability to access the legacy product from long distances. A serial-to-Ethernet converter provides a simple solution to solve the above challenges. The software described in this application report allows an Ethernet-based TM4C129x microcontroller to be used as a serial-to-Ethernet converter. TM4C129x microcontroller is ideally suited for this application due to the integration of MAC and PHY on the microcontroller along with on-chip voltage regulator. This allows quicker time-to-market and cost savings. The software uses FreeRTOS to schedule the various tasks and runs out of the box on an EK-TM4C1294XL board.

Project collateral and source code discussed in this application report can be downloaded from the following URL: http://www.ti.com/lit/zip/spma072.

Trademarks

Code Composer Studio, Tiva are trademarks of Texas Instruments.

Keil is a registered trademark of ARM Limited.

IAR is a trademark of IAR Systems AB.

All other trademarks are the property of their respective owners.

1 Introduction

When a legacy product only contains a serial port for configuration or control, continuing to access the legacy product through the serial interface can become challenging over time. The following are the challenges of using a serial port:

The inability to add multiple such products to a shared network
The inability to access the legacy product from long distances
Modern PCs generally do not have RS-232 ports

Using Ethernet in place of the serial port provides the following benefits:

The legacy product can be more easily shared (instead of changing a cable connection, a new connection over the existing network is made)
Ability to access from longer distances. Cable length is no longer an issue
Ethernet is a more common interface available on today’s computing equipment

The software described in this application report (enet_s2e) allows an Ethernet-enabled TM4C129x microcontroller to be used as a serial-to-Ethernet converter. By connecting a serial-to-Ethernet converter to the serial port of a legacy product, it can be given the ability to operate on the Ethernet without requiring any changes to the existing hardware or software. This is especially useful when the legacy product cannot be modified (such as in the case of third-party products).

The software works out of the box on an EK-TM4C1294XL board. With minor modifications, the software can run on the DK-TM4C129X board. For details, see Section 3.2.

FreeRTOS has been used for scheduling the various tasks. Although an RTOS is not a requirement for this application, it has been used to make the application easily scalable.