
Chapter 2
Using Your 653X
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National Instruments Corporation
2-11
Figure 2-3.
Connecting Signals
If you are using the burst protocol, make the connection to the appropriate
PCLK pin on the 653
X
device.
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 653
X
device 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
653
X
device:
1.
Configure the 653
X
device for a mode compatible with your peripheral
device.
2.
Configure and reset the peripheral device, if appropriate.
3.
Enable the input device (653
X
device or peripheral device) and begin
a transfer.
4.
Enable the output device (653
X
device or peripheral device) and begin
a transfer.
To control this initialization order, you need to enable and disable the
peripheral device and control the order in which the 653
X
device 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