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Application Notes
auto-exposure mode unless Address 130d[2] is set to 0. For more information concerning
auto-exposure, refer to LC99704B-WK3 Sanyo DSP Specification, Version 1.
2
Digital and analog gain controls can be varied over the I
C interface. Use both the digital
and analog gain to achieve a maximum gain of over 30 dB. Bar code reading applications
do not use the digital gain control since it provides no true signal amplification value. Write
2
values to I
C register 157d to set a particular analog gain as outlined in
Figure
5-7. Once
written, the analog gain changes a minimum of 3 dB each subsequent frame until the
desired value is reached. If the analog gain is set to a level less than 3 dB from the current
value, the correct analog gain takes effect on the read-out of the subsequent frame.
In Mode 1 the SE4400 starts in auto-digital gain and auto-analog gain mode. Set Address
130d[0] and Address 130d[1] to 0 for manual digital gain and manual analog gain,
respectively. In Mode 3 the SE4400 defaults to manual gain mode. To change this, set
these addresses to 1. For more information concerning auto-gain, refer to LC99704B-WK3
Sanyo DSP Specification, Version 1.
Figure 5-7. Analog Gain Control
5-17
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