BitFlow NEO-PCE-CLB, Hardware Reference Manual

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CON15 Register The Neon
NEO-4-8 BitFlow, Inc. Version G.5
mechanical system backs up and moves forward (jitter). This re-acquisition can cause
problems as the resulting images will have distortions and will not accurately repre-
sent the object in front of the camera.
Programming this bit to a 1 turns on the no-reacquisition circuit. This circuit eliminates
this problem as each line in the image will only be acquired once, regardless of how
much jitter occurs in the quadrature encoder input. The circuit does this by making
sure that only one line is acquired for each encoder counter value. If the quadrature
encoder backs up, and then moves forward, the board will not acquire lines until a
new encoder counter value is reached.
This system handles any amount of jitter, regardless of how many times the counter
passes through a value, or to what extremes the counter goes. New lines will only be
acquired when new values are reached.
Once the entire frame has been acquired, the system must be reset. The system can
always be reset by poking QENC_RESET to 1. There are also ways that the system can
automatically be reset, see QENC_RESET_MODE.
QENC_DUAL_
PHASE R/W, CON15[29], Karbon, Neon
This bit controls which type of encoder is attached.
SCAN_STEP_
TRIG R/W, CON15[30], Karbon, Neon
The scan step circuit uses the encoder to generate a trigger to the system. The scan
step trigger generates a trigger every N lines (N is set in the SCAN_STEP register).
QENC_NO_REAQ Meaning
0 Lines are acquired every change in the encoder
counter (as controlled by QENC_AQ_DIR)
1 Lines are only acquired when the encoder counter
reaches new values (also controlled by QENC_AQ_
DIR)
QENC_DUAL_PHASE Meaning
0 A single phase encoder is attached
1 A quadrature encoder is attached
SCAN_STEP_TRIG Meaning
0 Trigger comes of the normal source
1 Trigger comes from the scan step circuit