Monday, 27 April 2015

Yosemite and USB-422 Latency

Having updated Mavericks for USB Latency I was still getting a few emails from customers about Yosemite.  Because I use my macbook as my main machine running Mac, Windows and DOS and do all my work on this computer I was reluctant to upgrade just in case of problems.

Whilst in the USA for NAB I bought a new macbook with Yosemite pre-installed I can now use this machine for trying out new programs. I followed the posted instructions and disabled the Apple driver. You can use the 'ls' command to check that the driver has been disabled (Renamed). I then went to the FTDI web site where I discovered that FTDI had posted a new driver for the Mac that very same week! Version 2.3 2015-04-15. I installed the new FTDI driver, used KextDrop to add the low latency driver and restarted the computer. Everything worked OK and the port was discovered correctly.

I had to wait until I got back to my office to measure the latency, as you can see below it measures at 1mSec s expected. The Yellow trace is the command from the Mac via the USB422 and the Blue trace is the reply from our RM-6 synchroniser. They are both set up to send a message immediately after receiving a message. The USB runs a 1mSec poll so that there is approximately a 1mSec delay on the Mac. The embedded software reacts a lot faster as it is not limited by the USB Poll.

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