Here is the final segment of an excerpt from uC/TCP-IP, the Embedded Protocol by Christian Legare. In this third chapter of the book, we look at how to actually embed TCP/IP and the common challenges and solutions you’ll need to work through.
3-2-7 µC/TCP-IP ADD-ON OPTIONS DATA FOOTPRINT
The RAM data usage for the µC/TCP-IP add-on options is provided for planning assistance. In the following table, we use the definition of the size of CPU_STK as being 4 bytes.
Several considerations are necessary when adding a TCP/IP stack to an embedded system. Most of these are performance related, including:
- The CPU’s ability to process all of the packets to be transmitted or received
- The Ethernet Controller type has an impact on the driver
- The transfer method between the Ethernet Controller and the TCP/IP stack has an impact on performance
- Byte copy from one location to another via the CPU
- DMA transfer
- The Zero-Copy architecture of the TCP/IP stack has an impact on performance
- The code and data footprints:
- Code footprint depends on what protocols are used and this depends on what the specific goal of the application.
- A data footprint is largely affected by the number of network buffers required. Chapter 7, “Transport Protocols” on page 167 gives the means to evaluate the number of buffers a system should configure. Sample applications provided in Part II of this book and the µC/IPerf application found in Chapter 6, “Troubleshooting” on page 137, provide additional means to evaluate a system's performance based on its configuration.
Next, we will examine Ethernet in the first layer at the bottom of the reference model to discover its importance in the product design. Ethernet driver development and test represent challenges the embedded engineer must face. We will then move up through the layers on our way to the Application layer, finding additional obstacles to overcome in order to efficiently embed a TCP/IP stack into a product.
Chapters of "µC/TCP-IP, the embedded protocol" are provided to UBM for users download and consultation, not for resale. Users wanting to know more about TCP/IP and Micrium can visit Micrium.