Xmos has designed a modular prototyping board for its XA devices, which combine the company’s own real-time, multithreaded processor core with an ARM Cortex-M3 microcontroller based on Silicon Labs’ Gecko architecture.
The first I/O board for the core processor module is aimed at industrial networking. A lot of the protocols in use are based on standard interfaces and protocols such as RS485, CAN and ethernet but often have proprietary extensions or use the standard protocol in odd ways. New versions of ethernet are popping up that offer time-triggered or fixed-schedule modes to try to improve their real-time performance. Those exceptions can be handled in software by putting a large chunk of the stack on the Xcore.
Pete Tasker, product manager at Xmos, said: “With some fieldbus versions of CAN there is a requirement that the CRC check is maintained so that it can be propagated through the system. Most hardware implementations throw it away. We can store it so that it can be propagated onto a packet that’s sent out over ethernet, for example.”
Having the ARM provides compatibility with existing middleware, Tasker said: “When it comes to fieldbus standards, they often have an existing ARM code base which can be reused on the XA. We envisage that the ARM will continue to do the higher-layer stack processing and the Xcore will do the lower-layer stuff.
The core board uses an I/O pinout defined by Xmos, onto which the industrial networking module fits. The company expects to produce others. Although a number of other chipmakers have made their prototyping boards compatible with Arduino shields, Xmos has opted for its own layout.
“The XA is quite a powerful chip. We didn’t want to limit its capabilities. It can do things an Arduino never would. However, we do like the idea that there is a social networking element around [platforms like Arduino],” said Tasker.
Xmos sees it is still possible to link to I/O boards or shields from ecosystems such as Arduino by using an interposer. Rather than Arduino specifically, the company currently favours the Click Board concept developed by MikroElektronika. “At Embedded World earlier this year there was a real hubbub around Mikro and an ecosystem has sprung up around the Click Boards. They can do interesting things like provide a GSM modem or touch-sensitive control.”
For debugging on the XA carriers, Xmos provides both its own debug software and interface with ARM access made through a built-in version of the Segger debugger.