VXI Technology, Inc.
32
VM1548C Programming
The
OUTP:CLOC:ENAB <port> ON
command configures the front panel clock connection to
the output mode. This allows the VM1548C to drive these lines clocking the UUT. The timing
and control circuitry generates the IN*/OUT <port> signal to the I/O data and word buffers
configuring them as inputs when the
SOUR:DATA:ENAB <port> 1
commands are received.
The
INP:REG:SOUR <port> TTLT
commands select the VXI TTL trigger in as the clock input
for the trigger method to input data from the UUT. This clock is transmitted from the front panel
connectors, clocking the data out of the UUT. When the commands are received the VM1548C
timing and control circuitry will generate the PORTENA* signal to the port decoder. The port
decoder then clocks the write clock enable latch selecting the CLKINENA. The CLKINENA
signals are applied to the I/O data and word buffers enabling the input clock line.
The
INP:REG:POL <port> INV
command
causes the timing and control circuitry to select the
falling edge of the TTL trigger in as the CLKIN <port> for the I/O data buffers.
When
INP:TTLT:STATE ON
command is received, the VM1548C timing and control circuitry
generates the PORTENA* signal to the port decoder. This clocks the trigger select latch selecting
the TINENA line. The TINENA signal enables the trigger in mux.
INP:TTLT 1
notifies the
timing and control circuitry to select TTL trigger 1 for the clock source. The port decoder is again
enabled to clock the trigger select latch selecting the TINSEL signals. These signals are routed to
the trigger in mux that enables TTL trigger 1 to be routed to the timing and control circuitry for
clocking the UUT and the I/O data buffers. The normal polarity of the trigger is sent to the UUT
and the inverted version is used for the I/O data buffers.
The
STAT:INT:ENAB
command uses the default value of NONE (ground) to generate the status
interrupt onto the VXI backplane and the
STAT:INT:PTR ON
command set the polarity of the
interrupt. When the TTL trigger 1 occurs, the VM1548C will send a high going pulse to clock
data out of the UUT. The falling edge of this pulse is used to latch the data into the VM1548C’s
I/O data buffers. The VM1548C sends an Interrupt Request (IRQ*) informing the slot 0 controller
via the VMIP that the transfer has occurred and that the data in the I/O data buffers is now
available. The READ? <port> command causes the timing and control circuitry to generate two
READ signals. The first READ signal is routed to the I/O word buffers thereby enabling them to
output data to the read/write data buffer and onto the VMIP bus. The second signal READ (0,2,4)
then clocks the I/O word buffer. The I/O word buffer will output one 16-bit word at a time.
Note that data inputs to the module do not contain pull-up or down-biasing resistors. If the user
does not provide active or passive biasing of the data inputs, a read of the port may result in either
a “1” or “0” being read from the data inputs.
Содержание VM1548C
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