#Different domain iclock code

In this type of implementation read and write pointers are converted into gray code first and then clock crossed into opposite clock domain. Cummings- SNUG 2001Īsync FIFO: Async FIFOs are used for clock crossing data bits or large group of signal buses. Synchronized Load Pulse with Feedback : Courtesy: Clifford E. Here’s an example of closed loop solution using Synchronized load Pulse. It can be used to transfer critical control bits from one clock domain to other. The feedback Mechanism is done using a simple FSM and feedback signal from destination domain needs to be clock crossed as well.ĭue to Feedback mechanism, this type of solution is slower compared to open-loop but more reliable. This reduces the chances of Metastability even further as original signal is re-tried if clock synchronization does not happen correctly. Synchronized Load Pulse with Feedback : In closed loop solution a feedback from destination clock domain is received before sending the next signal from source clock domain. Synchronized Load Pulse : Courtesy: Clifford E. Synchronized Load Pulse: Another Open loop solution is to pass a synchronized load pulse to destination domain and then use this synchronized pulse to flop in Data bits as shown. The conversion from Gray to Binary is discussed in Async FIFO post. This allows Synchronizer to be effective as there is less probability of Metastability. Conversion to Gray code allows 1-bit difference between signal updates.

Cummings- SNUG 2001īinary to Gray Conversion : If we have Multiple bits or a Signal Bus crossing clock domain then it can be converted into Gray code. 2 D-FLOP Synchronizer : Courtesy: Clifford E. Example below shows the 2 D-Flop Synchronizer. The general rule is period of destination clock should be 1.5 times of source clock period. We may also use 3 stages of D-Flops if needed but 2 D-Flops are sufficient for most of the cases. The 2 Flops allow signal to settle down and sample it correctly without getting into Metastable State. The process of synchronization can be broadly categorized into 2 types.Ģ-D flop synchronizer: Here the source signal is flopped twice on destination clock before its used by destination logic. If the synchronization is not performed then it could result into Metastability of the signal & could result into incorrect sampling of the signal at the receiving flop. The signal from source domain needs to be synchronized to destination domain before it can be used. For Lowest, dealer and best price Contact Us at 01979-234344.Clock domain synchronization is required when we have signals crossing logic domains that are running on two different Frequencies that are Asynchronous to each other. You can buy the ZKTeco iClock 700 time & attendance and access control terminal at best and dealer price from Our Head Office (Dhaka, Motijheel), IDB branch, Multiplan branch, Uttara Branch, Chittagong (chattagram) showrooms.

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