National Instruments 653X - Manual (Page 29)

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