STV-DCA/VGA-E01 STMICROELECTRONICS [STMicroelectronics], STV-DCA/VGA-E01 Datasheet - Page 12

• Manufacturer Part Number: STV-DCA/VGA-E01
• Description: Low Cost Digital Camera (LCDC) Chipset
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Digital Camera Chipset; Customer Datasheet, Rev 3.0, March 2000
2.3
An on-chip battery level detector on STV0680A detects when the battery voltage falls below a threshold. This threshold is
determined by the designer, dependant on the perception of what remains as ‘acceptable’ image quality as the battery voltage
falls. The chosen threshold level is determined by a resistor value, as shown in Section 9. Where no USB has been detected, the
LCD display flashes, which indicates that the battery is low. Where a USB connection has been detected, the camera sources
power from USB, if certain additional hardware is fitted.
Note: It may be a requirement of certain USB compliance tests that such additional hardware is included in the camera design, in
order to enable the camera to switch to supply from USB and hence report back to the PC while connected to the USB bus
without a battery.
2.4
Either USB Interface (full speed 12Mbit/sec max.) or RS232 interface (115.2Kbaud) is supported by the chipset, with driver
software available from ST for both. The interface type is auto-detected by the chipset. PC software can be one of the following
(exact compatibility is clarified in Table 3):
2.4.1
Complete images (displayed as either thumbnails or in full resolution), or the entire SDRAM contents (e.g. for uploading
continuously captured image sequences, recorded using ‘Continuous Capture’ mode) can be downloaded through USB, and
USB connection also allows for tethered video mode to be activated by the USB driver.
Thumbnail image download is extremely fast for the entire memory contents in the camera. Once a picture is selected for
download, full image download takes approximately 0.15 seconds per image for a CIF image (0.6 seconds for a VGA image),
plus post processing time per image.
For USB interface details, see Section 4.4.
Note: Actual USB download and post processing time also depends on PC performance and USB bus loading
2.4.2
Thumbnails of images, complete stored images, or the entire SDRAM contents can be downloaded through RS232, but tethered
video is not supported.
Once a picture is selected for download, full image download takes approximately 10 seconds per image for a CIF image (around
30 seconds for a VGA image), plus post processing time per image (of the order of 1 second approximately).
For RS232 interface details, see Section 4.5.
Note: Actual post processing time after RS232 download also depends on PC performance
2.5
The chipset operates automatic exposure and gain control for either 50Hz or 60Hz mains-driven indoor lighting, using the same
12MHz crystal. This improves picture quality by selecting a set of exposure values which minimise ‘flicker’ effects. Detection of
STV0680F_contents.fm
2. Camera has been ‘gone to sleep’ i.e. moved into standby mode. Pictures are retained in memory.
3. Picture has been successfully taken after the user presses the capture button.
4. Picture has NOT been taken after the user presses the capture button. This indicates to the user that there is insufficient
5. Picture has NOT been taken after the user presses the capture button, due to picture counter having reached the maximum
6. End of continuous capture in un-tethered ‘Continuous’ mode, due to memory full.
7. Self-timer activated and counting down.
1. Simple image upload demonstration software supplied by ST, allowing uploading of stills or ‘continuous’ images. This soft-
2. TWAIN driver to suit all TWAIN compatible imaging applications
3. Video for Windows driver for tethered video mode (USB only)
4. Custom end-user software developed by OEM using SDK (for SDK availability, contact ST). The SDK is supplied by ST as a
light, or that the exposure control was not ready due to a rapid change of lighting in the scene.
number of images. The user has the chance to zero the counter if desired.
ware should not be supplied as an end-user product.
32-bit DLL format, running on Windows 98, and accessed through a documented software interface. This provides the basis
for developing a custom software application for uploading stills and/or video. See Section 5. for further details.
Battery Level Detect and USB auto-switch
PC interface options and software support
Anti-flicker exposure and gain control
USB
RS232 (not available on STV0680-001)
Commercial in confidence
CDSTV0680F-C
PRELIMINARY
STV0680A + VV6444/6410/6500
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