Timing in digital circuits

Read Time series Diagram method

1, from top to bottom, from left to right, high in the upper, low level in the lower, high impedance state in the middle. Two-line representations may be high or low, depending on the data. The intersection line indicates the high and low points of the state, which can either be higher or lower, or it can be unchanged.

2, the vertical line is the lifeline, represents the time series of the object for a period of the existence of the sequence diagram of each object and the bottom center has a vertical segment of the dashed lines, this is the object's lifeline, the object's message exists between the two lifelines.

3, the timing to meet the establishment time and retention time constraints to ensure that the lock to the correct address. Timing drawing of data or address lines 0/12 lines indicating a fixed level, either "0" or "1" depending on the specific address or data; Crossed lines indicate level changes, state uncertainties, and values are meaningless.

Such as:

hcntl,hr/w shaded sections indicate unrelated data periods, non-shaded areas are valid stable data areas, and intersection lines are data-changing points of time.
The longitudinal longest dashed line is the reference point for data and control signal acquisition, i.e., the falling edge sampling of the Hstrobe
In the case of output readout data, both the shadow and non-shaded areas are read-out data time periods, but the shaded area represents the unstable period, and the non-shaded area represents the stable validity period of the data, which can be sampled to read valid data at the moment. The OUTPUT Middle horizontal line indicates a high impedance state of the data.

Timing in digital circuits