Agilent Technologies L4400 manual 208

8L4450A 64-Bit Digital I/O with Memory and Counter

Synchronous Buffered Outputs You can use synchronous mode handshake with buffered (memory) output operations. (Buffered operations are described in more detail beginning on page 210.) For buffered output operations, the H0 line acts as a start/stop line. This line will be set high when the memory output command is executed by the L4450A and will return low when the memory output operation has completed.

Synchronous memory output operations can be paced using either the internal strobe or an external strobe.

When using the internal strobe, the H1 line is the strobe output line. The timing of the output operation when using the default INTernal clock is controlled by the CONFigure:DIGital:HANDshake:RATE command.

This setting affects strobe width, memory clock rate, as well as the setup and hold times. Alternatively, the reciprocal form of the command CONFigure:DIGital:HANDshake:CTIMe can be used to specify the speed in terms of time instead of a rate. The timing should be set such that the device receiving the data can latch the data lines during the TCYCLE time.

The receiving device should detect the leading edge of the strobe line, wait for the L4450A to set the data (TPD) and then latch the data. Latching the data on the trailing edge of the strobe is recommended, however, you can the data following TPD. TPD ranges from - 23 to 23 ns.

A synchronous buffered output using the internal clock is shown in the diagram below (default handshake line polarity).

H0 (Start/Stop)
	TCYCLE / 2	TCYCLE
			(Last Cycle)
H1 (Strobe Out)
	TPD	TPD	TPD
Data Out	Invalid	Valid

208 L4400 User’s Guide