Texas Instruments L137 DSP Project

Dual-core ARM-DSP

See our writeup for the ARM details of the L137 on this website.

In 2009, becalmed in the middle of the eye of the global financial storm, we bought a Spectrum Digital/ Texas Instruments OMAP-L137 board to evaluate the ARM, however, the DSP came up first and we ended up writing for the 674xx compatible VLIW DSP. We did not test any DSP algorithms, but programmed the on-board and on-chip peripherals in C. From the software view of the board (without interrupts enabled), the code was no different to that of any RISC. The processor can access bytes on any boundary. We are not sure if the promised Linux port ever shipped for the L137 board, but two years on, it is “shelfware” as newer devices are just so much more capable — the technology treadwheel never stops!

Spectrum Digital L137 board

Ethernet Testing

We bought the L137 board to test Ethernet on an ARM core with external memory so that we would not be constrained by the limited amount of RAM in typical ARM microcontrollers with Ethernet. The Luminary Micro and size constrained IAR compiler still haunted us, as mentioned in LM3S6965 Ethernet Evaluation on this website. The promised Linux port would make it attractive, but we feel that Spectrum Digital’s interest is more in the DSP side than the ARM. There was precious little for debugging the ARM side in the way of examples or code, particularly as the DSP booted first.

Future DSP Projects

The board was inexpensive and includes decent connectors for expansion boards (Samtec will supply prototype quantities), so it was also useful for keeping for any single core TMS674x floating point benchmarking. For the ARM side, much more capable devices are available in 2011 from Texas Instruments and Freescale.

Any future DSP projects are likely to be for imaging and to test SRIO. Other SRIO candidates are PowerPC from Freescale and cores from Lattice Semiconductor. For now we are working on ARM with some Lattice work in the pipeline. If these are of interest, send us an email.