Enable Signals
The standard defines 4 enable signals:
- FVAL —Frame Valid— is defined HIGH for valid lines.
- LVAL —Line Valid— is defined HIGH for valid pixels.
- DVAL —Data Valid— is defined HIGH when data is valid.
- Spare has been defined for future use.
The standard requires that all four enable signals are provided by the camera to all channel links. For the 80-bit configuration, only two signals —FVAL and LVAL— are delivered by the camera.
The enable signals are used differently according to the selected acquisition mode.
Acquisition mode |
FVAL usage |
LVAL usage |
DVAL usage (*) |
Spare usage (**) |
Area-scan |
Start of frame |
Start of line |
Clock enable (optional) |
Unused |
Line-scan |
Unused |
Start of line |
Clock enable (optional) |
Unused |
Raw grabbing |
Frame cover |
Unused |
Clock enable (optional) |
Unused |
(*) The usage of DVAL is optional. By default, the board is configured to ignore DVAL.
(**) The spare signal is always ignored.