Rising clock edge

Here is an example of a Moore finite state machine. A reg variable] MooreState is used to model the machine state which can have either of] the four states. The event list indicates that the state transitions occur synchronously on every rising clock edge. 

Here is a model of a modulo-binary up-counter. This counter has only a synchronous preclear control and all transitions occur on the rising clock edge. 

Fig. D.6. (a) A simple T-flip flop implemented using NAND gates (b) the symbol for a T flip-flop. Q is the output, Q is the inverse of the output. When a rising clock edge is applied to T, the state switches from on to off or vice versa. More sophisticated latches may be necessary to prevent race conditions depending on the transistors used.

If the initialization signal, INTT, is high the normal shift operation occurs. The register will be initialized if INIT goes low. These operations inside a process are synchronous when a Wait statement is used with the dock expression. The trigger in this case is a rising clock edge. See Box 5.7 for more details on this construct. 

Flip-flops are state storage elements which have provisions for programming and, in many cases, clocking. One architecture which is useful for making clock dividers is known as the T flip-flop, whose design is shown in Fig. D.6. The T flip flop stores state when the input is steady, but inverts its output state on a rising input edge. 

These preclude a signal from being assigned on both a rising and falling clock edge or on different clocks. 

The semantics of the always statement implies that all statements in are to be executed only when a rising edge or a falling edge of clock occurs. We shall call this special always statement as a clocked always statement. 

Here is a model for a parameterized N-bit binary up-down counter with synchronous preset and preclear controls. The counting is synchronized to the rising edge of a clock. 

Here is the behavioral model for the transmitter block TX. This model is a synthesizable model. Rising-edge-triggered flip-flops are inferred for variables TBR, TR, TRE, TBRE, DOUT, CBTT and PA this is because these variables are assigned values under the control of clock CK. 

Here the intention appears to be to store the value of PresentState in a flip-flop (rising-edge-triggered). After synthesis, not only is there a flip-flop for PresentState, there are also four flip-flops for Zout. This is because Zout is assigned under the control of a clock. It may or may not be the intention to generate flip-flops for Zout. If not, then a case statement needs to be written in a separate always statement in which Zout is assigned, this... 

Direct Rambus A memory bus that transfers data at 800MHz over a 16-bit memory bus. Direct Rambus memory models (often called RIMMs), like DDR SDRAM, can transfer data on both the rising and falling edges of a clock cycle. 

Startpoint f reg (rising edge-triggered flip-flop clocked by dk)... 

Clock clock Sense rising edge Asynchronous Reset Unspecified... 

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