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CMV50000

Functional Description

Datasheet

• PUBLIC

DS000522

• v4-00 • 2023-Aug-03

136

│ 90

On-Chip OBC

Setting EOB_BYPASS to 0 enables the automatic on-chip black level correction (clamping). In this

mode, BLACK_LEVELADC_OUT is calculated on-chip, based on OB pixels, for every row allowing to

correct for row and frame noise in the image.

This is the recommended mode of operation.

Off-Chip OBC

Setting EOB_BYPASS to 1 disables the automatic OBC. BLACK_LEVELADC_OUT is now specified with

register EOB_BYPASS_VALUE. This value is constant and cannot correct for row noise in the image.

Equation 17:

������������������������������������������_������������������ = ������������������������[������������������������������������_������������������ − ������������������_������������������������������������_������������������������������ + ������������������_������������������������������������]

Further external or off-chip OBC can be achieved by reading out the OB pixel data (refer to section

7.8.5

).

7.7.2

Analog and Digital Gain

Register GANA is used to set the analog gain. When changing the analog gain, the OB black level

also has to be fine-tuned to have optimal black level clamping.

Figure 116:

Analog Gain Registers

Reg. Name

Bank

Addr

Bits

Description

GANA

0

78

[7:0]

See settings in 7.4.2

EOB_OFFSET_FINE

1

38-39

[15:0]

See settings in 7.4.2

Digital gain can be specified for the 4 color channels individually (even/odd columns, even/odd rows).

E.g. GDIG_RE_CO relates to Rows Even and Columns Odd.

The digital gain for each channel is defined by a similar equation:

Equation 18:

������������������������������������������ ������������������������ (������������_������������) = (������������������������_������������_������������ + 1)/16

Base (default) digital gain is set by uploading a value of 15 to GDIG_Rx_Cy. The maximum digital

gain is 16x with GDIG_Rx_Cy at 256. The lowest digital gain is 1/16x with GDIG_Rx_Cy at 0.