Counter Read

The user can read the counter values for Counter Input applications using the following options:

• Single Point (On-Demand) Read
• Implicit Buffered Read
• Buffered (Sample Clock) Read

Single Point (On-Demand) Read

With single point (on-demand) edge counting, software can read the counter contents at any time without disturbing the counting process.

The following figure shows an example of a single pulse-width measurement. When the signal-to-measure goes inactive, the counter stores the count in the FIFO and ignores other edges on the signal-to-measure and the counter timebase. Software then reads the stored count.

Implicit Buffered Read

With implicit buffered read, the measured signal determines when data is latched in. The counter stores the data in the counter FIFO.

The following figure shows an example of an implicit buffered pulse-width measurement. On each trailing edge of the signal-to-measure, the counter stores the count in the counter FIFO. The TestScale backplane transfers the sampled values to host memory using a high-speed data stream.

Buffered (Sample Clock) Read

With sample clock buffered read, the value of the counter is sampled on each active edge of a sample clock and stored in the FIFO.

The following figure shows an example of a sample clocked buffered pulse-width measurement. The counter counts the number of edges on the counter timebase while the signal-to-measure remains active. On each sample clock edge, the counter stores the count in the FIFO of the last pulse width to complete. The TestScale backplane transfers the sampled values to host memory using a high-speed data stream.