FarSync Drivers | ![]() |
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Some of the FarSync device support an on-board clock synthesiser, and it is therefore possible for non-standard clock rates to be configured. There can be one custom clock rate per port. This requires the use of an external tool called the VersClock II Programmer to generate a clock string. You will find a copy of the tool in the VersaClock directory, but you should check with the chip vendor if there is a later release.
The process of setting the clock rate manually or programmatically is described below.
The following describes how a user can program a FarSync Synthesiser capable device to generate non-standard user defined clock rates using the onboard synthesizer.
The FarSync device firmware supports a wide range of preset standard clock frequencies built in, but when non-standard frequencies are required, a design tool from the synthesizer manufacturer may be used to calculate the programming sequence.
These non-standard frequencies may be configured prior to a port being opened (static), or may be configured and changed while a port is open and running (dynamic).
Some restrictions apply to dynamic clock adjustment and are described later in this document.
Firstly, go http://www.idt.com and search for the product page on the ICS307G-03LF device, then locate the link for the VersaClock II Desktop Software Setup and download and install the application. The tool itself comes with a full User Manual, but the following notes detail its use specifically with FarSync products.
The VersaClock II Desktop application opens with the following screen:
Select the Part Number as shown, then click Continue:
Select Show Programming Word and Manual Pin Assignment from the Options menu:
Select a Ref freq (MHz) of 8.192:
Select the Desired MHz for Pin 8 (64500Hz in this example), leave the Error ppm blank:
Click on the Calculate Button:
For a generated clock that closely matches your requirements look for 5 green bars and 0 ppm. Less than 5 green bars and/or more than 0 ppm may be acceptable in some applications, it is left to the user to make this judgment.
NOTE: A minimum frequency of 0.032MHz (32KHz) is recommended at the synthesizer output. To generate lower frequencies, multiply the desired frequency by 256. When using dynamic clock adjustments, it is important that you do not switch between a clock that requires a divide by 256 and one that does not. For dynamic clock adjustment, in order to achieve a glitch-free transition from one clock to another ,there should be no change in the synthesizer output divider configuration.
The Pin Map shows the pin out of the device and the calculated 16½ byte Programming Word:
Click on the Prog. word to Clipboard button:
Please save this string in a text file for now as it will be required either in a fautil command to manually set the clock rate, or you can past it into you application if you are requiring the set the clock rate programmatically.
To use farutil to set the custom clock rate manually you need to supply two pieces of information:
These are then used in the farutil command as follows:
farutil sync0 set clock 64500 custom_rate 0000177BE8C00000000000000006FFFC6
The custom clock rate will take effect the next time that the port is opened. Note that it is important that the "clock" keyword appears before the "custom_rate" keyword, as the processing of the "custom_rate" will use the current value of "clock".
The custom clock rate can also be set through the ioctl() interface to the driver. Please see the FarSync SDK documentation for further details, and you can reference the switch_speed example application to see how this feature can be used to dynamically change the clock rate of the device.
If you are using and encoding mode where clock synchronisation is encoded in the data, for example FM0, FM1, Manchester etc, then a few of the steps outlined above need to change.
If you receive the following message when you try and run the VersaClock tool from the desktop
Then please follow the steps below.
The application can now be launched from the desktop icon.
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