Kvaser MagiSync™ is patented by Kvaser and it represents one of Kvaser’s key technologies.
Time synchronization is needed to achieve accurate and precise time stamping between several PC-to-bus interfaces connected to one PC. Since each PC-to-bus interface uses its on-board clock to set the time stamps.
Kvaser MagiSync™ is a new innovative way to synchronize several different Kvaser USB interfaces. You do not need external cables – you get instant synchronisation when you connect the Kvaser USB unit. All Professional and SemiPro units possess this feature. Kvaser MagiSync™ is patented solution and represents one of Kvaser’s key technologies.
The foundation of Kvaser MagiSync™ is the accurate time stamping of what we call reference events, events that are guaranteed to occur within a limited time period on all synchronised devices. The event used in the Kvaser Leaf’s is the USB SOF packet, a packet delivered to and identified by all device controllers in a USB tree within at most 500 ns. The worst case scenario of 500 ns can easily be made a lot less by simply connecting all devices at the same hub level and using cabling of equal length for all hubs. When the USB device controller identifies the SOF’s it asserts an interrupt to the microcomputer. The interrupt is connected to trig a capture register that reads and saves the present time of the microcomputer without its direct intervention. The interrupt handler then simply reads the captured time, assigns it the SOF sequence number for easy identification of the exact event and sends it to the drivers in the host computer.
The driver collects all time stamped reference events from the synchronised hardware and matches those events that refers to the same event with the time masters ditto. The set of matched pairs are then used to translate all further time stamped events (such as can messages etc) through simple linear regression. Recall from early school days the function
y – y0 = k * (x – x0), where k = (y1 – y0) / (x1 – x0)
x refers to the local time base of the devices and y is the common global time base.
The (xi, yi) are the matched reference event pairs mentioned above.
The pros of this approach are among others the simplicity by which devices can be built. With off-the-shelf hardware, that had to be there anyway, it can still outperform much heavier constructions that include dedicated hardware using FPGA’s. Already proven off-the-shelf hardware combined with the simplicity as such vouches for a clean stable highly reliable yet powerful product.