VD5377 datasheet(37/88 Pages) STMICROELECTRONICS

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Doc ID 022952 Rev 2

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VD5377

Key features

6.7

Automatic/manual frame rate

The VD5377 can operate in either automatic or manual frame rate control mode. The default

frame rate control mode is automatic (see Table 21, register 0x1c bit 4). This means that the

device adjusts frame rate automatically depending on the tracking velocity. By default, frame

rate is adjusted in the range 1 k to 2 k to Max. Because power consumption increases as

frame rate increases, automatic frame rate control is the most efficient in terms of power

consumption and requires no additional overhead from the host CPU. The maximum frame

rate to be applied in auto frame rate mode is set with register 0x1c bits 7:5. The default

maximum frame rate is 3.3 kf/s. Manual frame rate is selected with register 0x1c bits [2:0].

Due to CPU bandwidth limitations of the on-board MCU, maximum frame rate is limited to

3.3 kf/s in sunlight timing mode. In Normal DMIB timing mode only (default mode - register

0x51 = 0), the maximum frame rate may be increased up to 4 kf/s but in order to meet

internal timing constraints, the maximum exposure time (EXPOTIME_MAX 0x49) needs to

be reduced according to Table 22. The motion_threshold_low_comp (SPARE 0x32) should

also be updated.

Table 21. Adaptive frame rate control

Addr

(Hex)

Signal name

Bit

Type

Default

(Hex)

Comment

FRAME_RATE_CONT

ROL

frame_rate_sel

2:0

PRW

Frame rate selection (value for

internal osc running @48 MHz)

0 = 0.5kf/s (2 ms period)

1 = 1 kf/s (1 ms period)

2 = 2 kf/s (500 us period)

3 = 2.5kf/s (400 us period)

4 = 2.9kf/s (350 us period)

5 = 3.3kf/s (300 us period)

6 = 3.6kf/s (275 us period)

7 = 4 kf/s (250 us period)

frame_rate_ctrl

Frame rate management control

0 = Automatic (1 k / 2 k / Max f/s

auto frame rate)

1 = Manual (set with

frame_rate_sel reg)

max_auto_frame_r

ate

7:5

Maximum frame rate to be applied

in auto frame rate mode.

0 = not allowed

1 = not allowed

2 = 2 kf/s (500 us period)

3 = 2.5 kf/s (400 us period)

4 = 2.9 kf/s (350 us period)

5 = 3.3 kf/s (300 us period)

6 = 3.6 kf/s (275 us period)

7 = 4 kf/s (250 us period)

VD5377 数据表(PDF) 37 Page - STMicroelectronics

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