LM3S6965 Ethernet Evaluation

The Luminary Micro LM3S6965 Ethernet controller included a 100 Mbps PHY at a similar price to what we were paying for the Intel/ Level One PHYs. We tried the LM3S811 as a JTAG probe for the Ethernet board, but the Ethernet board also had its own JTAG interface. (It could also act as a JTAG debugger for an external Luminary Micro).

We sifted through some of our archives, but are not sure when the Ethernet trials started. There was a small web server application to increment a counter and flash an LED, but we were more interested in the UDP stack. A small TCP demo ran, but we could not compile the UDP side due to size constraints of the evaluation compiler. There were plenty of other distractions and costs competing for the same pocket as a compiler toolchain would come out of. Our resistance was that the Flash and on-board memory were too small to invest in Ethernet on the device. There were stacks that had changed the 32-bit counters to use 8-bit unsigned chars, but then testing on a host would be too difficult. Our future Ethernet work would not justify the investment in a new TCP/IP stack.

From the warehouse perspective, the Ethernet to RS-485 interface would mean that the user-interface at the end of each aisle could use a vanila x86 PC. The LM3S6965 had a couple of serial ports, so it could also handle a barcode reader and a serial keyboard, but we were being spread too thinly to look into something that would cost as little as a PC.