Chapter 2
Using Your NI 653X
2-22
ni.com
Figure 2-10.
Connecting Signals
If you are using the burst protocol, make the connection to the appropriate
PCLK pin on the NI 653
X
.
Choosing the Startup Sequence
To avoid invalid or missing data when the ACK and REQ lines change
polarity to either active high or active low, start a transfer using one of the
following methods:
•
Control the configuration and use an initialization order.
•
Select compatible line polarities and default line levels.
Using an Initialization Order
This startup sequence ensures the NI 653
X
is configured and is driving a
valid ACK value before you enable the transfer on the peripheral device.
Similarly, you can make sure the peripheral device is configured and is
driving a valid REQ value before you enable the transfer on the NI 653
X
.
1.
Configure the NI 653
X
for a mode compatible with your peripheral
device.
2.
Configure and reset the peripheral device, if appropriate.
3.
Enable the input device (NI 653
X
or peripheral device) and begin a
transfer.
4.
Enable the output device (NI 653
X
or peripheral device) and begin a
transfer.
To control this initialization order, you must enable and disable the
peripheral device and control the order in which the NI 653
X
and the
peripheral device are enabled. You can use the extra input and output lines
for this purpose.
ACK
REQ
I/O
Confirm
Ready
I/O
653
X Device
Your Peripheral Device
