Timing Considerations; Data Size Versus Bus Size - HP 3563A Operating Manual

Digital Connections
Connecting the Input Pods

Timing Considerations

Data
Data Clock
Qualifiers

Data Size versus Bus Size

The number of data bits doesn't always match the number of data lines on the bus. Use the
following configuration table to set up the analyzer. When the (input) bus size is 8 bits and the data
size is 16 bits, the analyzer multiplexes the incoming data and reconstructs the data internally. In this
case, 00 is used to differentiate between the qualifier patterns for the most-significant byte (MSE)
and least-significant byte (LSE). The clock qualifier word is the "address" of the MSE. The same
word, with 00 complemented, is the "address" of the LSE. See examples on pages 13-13 and 13-22.
When a channel is providing the sample clock, the LAST 1 /0 softkey (appears in the DATA CLOCK
menu when bus size is 8 bits and data size is 16 bits) is used to designate the end of a two-byte
transfer by specifying the state of 00 for the last byte. Otherwise, the data word is composed of the
last two bytes clocked into that channel before the sample clock. These two settings (values of 00
and Last) allow the two bytes to be read in either order as well as allowing either state of 00 to
indicate MSE. See the following examples and figures 13-22 and 13-23.
Notes
The MSE and LSE can be read fro m the analyzer in a variety of ways, but there
must be only one signal differentiating them; this signal must be used for 00.
The qualifiers 0 1
examples, that requires that the addresses must be consecutive. Not all consecutive
pairs work;
13-12
"ts u1 Data set-up time relative to data clock; 20 ns
t h1
Data hold time relative to data clock;
'ts u 2 Qualifier set-up time relative to data clock: 60 ns
t h2 Qualifier hold time relative to data clock;
(15
ns when moving i6-bit data on an 8-bit bus)
Figure Setup and Hold Times for Digital Inputs
13-1 1.
07 must be the same when reading MSE as for LSE.
-
and 6 are consecutive but more than one bit changes.
5
5
ns
5
ns
In
these