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PerkinElmer Optoelectronics
4.1.2.1 Exposure Control
Slave mode camera exposure is determined by the LR and LT signals which must
be timed with MCLK. The exposure time is defined as the time between the
rising edge of the LR signal and the rising edge of the LT signal. The LR signal
must be held active low (ON) for a minimum of 4 clock cycles and must be
inactive high (OFF) for a minimum of 4 clock cycles prior to the LT signal rising
edge. The LT signal must remain on (High) for at least 2 clock cycles and may
remain ON until 2 clock cycles prior to the next line transfer. Because there are
extra stages in the CCD readout register there must be at least N+41 MCLK
cycles between successive LT commands.
Figure 4 Slave Mode Timing
4.1.2.2 Slave Mode Data Output
The data output timing in the slave mode is identical to that of the master mode
taking note, however, that the CCLK, CLT and LEN signals are synchronized to
the externally applied MCLK.
Note 1.
Since the camera electronics stores a video line in memory prior to sending it to
the output, then when operating in the slave mode, the first line output after the
first LT has been issued is not valid.
Note 2.
CCLK – Analog video data can be sampled or digitized using the falling edge of
the CCLK signal, however the receive circuit propagation delays must be
carefully managed in the systems design.
