VV6444 datasheet(21/60 Pages) STMICROELECTRONICS

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STV0680A + VV6444/6410/6500

Digital Camera Chipset; Customer Datasheet, Rev 3.0, March 2000

PRELIMINARY

CDSTV0680F-C

Commercial in confidence

STV0680F_contents.fm

4.6.1

Power switching to USB

Included in the USB compliance requirements, is the ability of the camera to report to the PC when connected to the USB bus,

whether or not there is a fresh battery in the camera. This means that power sourcing from USB is required, which also saves on

battery life while the camera is used in USB tethered video mode. In order to allow switching from battery to USB power, some

additional hardware is required (see also Section 9.):

•

The USBDETECT input to STV0680A is used to detect that a USB power supply is connected

•

If the USB is detected, additional hardware is used to switch off the battery

•

An inrush protection circuit can protect the USB bus from current draw in the case of a low battery/battery not fitted. This may

be necessary to comply with the USB specification.

•

For precise USB compliance requirements, please consult the USB specification version 1.1

4.6.2

Switched sensor supply

Dependant on the hardware implementation, the SENSPWR output from STV0680A can be used to power off completely the

sensor during Standby mode (in the case of VV6444) or put the sensor into Suspend mode (in the case of VV6410/6500). This

has a significant improvement on battery life.

4.6.3

Battery type

This is hardware dependant. The schematics referred to in Section 9. assume either three or four 1.5V cells.

4.7

Quartz Crystal

Regardless of the sensor type or anti-flicker requirements, the sensor + STV0680A chipset operates from a single 12MHz

fundamental quartz crystal. For specification requirements, see Table 15. STV0680A includes an on-chip low jitter PLL, for PLL

characteristics, see Table 14.

4.8

Numeric LCD interface

STV0680A supports a 2-digit LCD panel only, for alpha-numeric display.

4.8.1

LCD types

STV0680A connects to a non multiplexed, direct drive LCD with 2 x 7 segments. Many LCD types are compatible with this

interface. The LCD refresh frequency is 34.7Hz.

4.8.2

LCD interface pinout

'0' connects to segment 'a', '1' connects to segment 'b', and so on, where a to g are standard for all 7-segment displays, as well as

an LCD common output, giving

fifteen signals in total.

4.9

Switches and LED’s

The GPIO lines on STV0680A have pre-defined functions as follows, see Section 2.2 for user interface functionality, and Section

9. for precise hardware implementation.

4.9.1

MODE push button and SHUTTER push button: GPIO0 and GPIO1

Both push button inputs have internal de-bounce circuits, reducing the amount of hardware required externally. It is

recommended that labelling is used on the camera casing to help the user understand the functioning of the 2-button interface.

4.9.2

Input to select between 50 and 60Hz flicker frequency: GPIO3

This allows for factory setting of the anti-flicker frequency, dependant on the final country of destination. See also Section 2.5.

The polarity of this selection is detailed in the reference design (see Section 9.).

The precise functionality of early demonstration units may vary from the actual user interface supported

by STV0680A.

! Note

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