Agilent Technologies manual L4400 User’s Guide 209

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

Optionally, you can provide an external strobe input on the H2 line to control the memory transfers. If you pace the memory inputs from an external clock, the L4450A will sense the leading edge of the strobe and set the data. The data will be valid after TPD and the receiving device may latch the data. TPD ranges from 140 ns to 60 ns. The maximum TPD of 140 ns limits operation in this mode to 7 MHz.

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

H0 (Start/Stop)
		TCYCLE
		(Last Cycle)
H2 (Clock In)
	TPD	TPD
		TPD
Data Out	Invalid	Valid

For example, using the internal strobe, the following SCPI commands set the L4450A to have a 32- bit output using synchronous handshake. The number of times to output the traces is set to 4. A trace is then loaded into memory and assigned to the channel. The memory is enabled and then triggered. The start/stop line is set high following the first byte handshake and remains high until the last byte is output.

CONF:DIG:WIDT LWOR, (@1101)

CONF:DIG:DIR OUTP, (@1101)

CONF:DIG:HAND SYNC, (@1101)

SOUR:DIG:MEM:NCYC 4, (@1101)

TRAC:DATA:DIG:LWOR (@1101), mytrace, #hFFEEFFEE, #hBCBC9999 SOUR:DIG:MEM:TRAC mytrace,(@1101)

SOUR:DIG:MEM:ENAB ON, (@1101) SOUR:DIG:MEM:STAR (@1101)

Using an external strobe, the following SCPI commands set the L4450A to have an 8- bit output using synchronous handshake with an external strobe input. The number of times to output the traces is set to infinite (continuous output until the memory is stopped). The memory is enabled and then triggered. The start/stop line is set high following the first byte handshake and remains high until the last byte is output.

CONF:DIG:WIDT BYTE, (@1101)

CONF:DIG:DIR OUTP, (@1101)

CONF:DIG:HAND SYNC, (@1101)

CONF:DIG:HAND:SYNC:STR:SOUR EXT, (@1101)

SOUR:DIG:MEM:NCYC 0, (@1101)

TRAC:DATA:DIG:BYTE (@1101), mytrace, 260, 139

SOUR:DIG:MEM:TRAC mytrace,(@1101)

SOUR:DIG:MEM:ENAB ON, (@1101)

SOUR:DIG:MEM:STAR (@1101)

L4400 User’s Guide 209