Choosing The Startup Sequence; Using An Initialization Order - National Instruments 653 Series User Manual

Chapter 2 Using Your NI 653X

Choosing the Startup Sequence

NI 653X User Manual
653 X Device
If you are using the burst protocol, make the connection to the appropriate
PCLK pin on the NI 653X.
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 653X 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 653X.
1. Configure the NI 653X for a mode compatible with your peripheral
device.
2. Configure and reset the peripheral device, if appropriate.
3. Enable the input device (NI 653X or peripheral device) and begin a
transfer.
4. Enable the output device (NI 653X 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 653X and the
peripheral device are enabled. You can use the extra input and output lines
for this purpose.
ACK
REQ
I/O
Your Peripheral Device
Figure 2-10. Connecting Signals
2-22
Confirm
Ready
I/O
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