VXI VT1433B manual Idle HL Sync/Trigger Line, Trigger Measure LH HLLH, Measurement Loop

VT1433B User's Guide

Using the VT1433B

In the BOOTING state, the digital processors of the module load their parameters and their program. Once done, the module releases the Sync/Trigger line and moves to the BOOTED state. The VT1433B stays in the BOOTED state until it sees a high-to-low transition of the Sync/Trigger line (that is, all the VT1433Bs in the system have booted).

In the SETTLING state, the digital filters are synchronized and the digital filter output is ‘settled’ (it waits N samples before outputting any data). Once the module is settled, it advances to the PRE_ARM state.

In the PRE_ARM state, the module waits for a pre-arm condition to take place. The default is to auto-arm, so the module would not wait at all in this case. When the pre-arm condition is met, the module releases the Sync/Trigger line and advances to the IDLE state.

This complete measurement sequence initialization, from TESTED through BOOTING, BOOTED, SETTLING, PRE-ARM and IDLE, can be performed with a call to the function hpe1432_initMeasure.

Measurement Loop

This section describes the measurement loop in the VT1433B.

The progression of measurement states and the corresponding Sync/Trigger line transitions are:

Idle

H L

Sync/Trigger Line

Arm

Trigger Measure

LH H LLH

Figure 3-9: Measurement loop

In the IDLE state the VT1433B writes no data into the FIFO. The VT1433B remains in the IDLE state until it sees a high-to-low transition of the Sync/Trigger line or an RPM arm/trigger point is calculated. If any of the VT1433Bs in the system is programmed for auto arming (with hpe1432_setArmMode), the Sync/Trigger line is immediately pulled low by that VT1433B. The VT1433B may also be moved to the ARM state by an explicit call to the function hpe1432_armMeasure.

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