Client: Alphatronics BV

Alphatronics creates, among other things, communication systems for healthcare.

For a new range of products the desire for a speaking listening connection from the client’s home to a central control room came up. It has been decided to realize this “speaking listening connection” by means of a SIP (VoIP) connection. MKSE had been asked to implement the SIP stack for the device at the client. This consists of the SIP protocol, associated protocols (including SDP and RTP), and the interface to the hardware (PCM).

This PCM interface was connected to a number of GPIO connections, because the controller does not have support for this. MKSE came up with a hardware modification that consists of adding 4 NEN ports, so that for a large part the existing SPI interface may be used. The processor load for controlling the PCM interface has been reduced from 90% to 9%. Important, since these devices have to do more than just VoIP.

Since the existing IP stack was not suitable for the SIP protocol (less than ideal realtime behavior, no ToS support, written for a specific, obsolete ethernet controller) MKSE introduced a new IP stack (Ethernet, ARP, IP, TCP, UDP, ICMP ) which solves the aforementioned restrictions. In addition, this stack is designed so that IPv6 can be easily added later.

Both stacks have now been delivered and tested satisfactorily, and will be used in future products.