Real Time Clock

RTC Implementation

Increment of Nanoseconds Field

Figure 8-2illustrates the implementation used to create the RTC nanoseconds field. This is performed by the use of an implementation specific 20-bit sub-nanoseconds field as illustrated. The nanoseconds and sub-nanoseconds fields can be considered to be concatenated together.

All RTC logic within the core is synchronous to the RTC Reference Clock, rtc_clk.

 

Nano Seconds (32 bits unsigned)

Sub-Nano Seconds

 

 

 

 

 

(20 bits unsigned)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Step 1

fill with zero’s

RTC Increment Value (26 bits)

(written by processor)

controlled frequency RTC

Step 2

RTC Nano Seconds Offset (30 bits) (written by processor)

Synchronised RTC

Figure 8-2:Increment of Sub-nanoseconds and Nanoseconds Field

Ethernet AVB Endpoint User Guide

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UG492 July 23, 2010

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Xilinx UG492 manual RTC Implementation, Increment of Nanoseconds Field, Real Time Clock