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ST VD5376 Application Note
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ST VD5376 Application Note

ST VD5376 Application Note

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1
Introduction
This document gives a non-exhaustive list of tests which may be run on the ST
VD5376/VD5377 optical finger navigation (OFN) devices.
2
Initialization
The initialization setup depends on the customer application (for example, automatic or
manual power mode, direct 1v8 drive or Vtop supply, CPI setting, X/Y direction and so on).
Please refer to the individual application notes for initialization instructions:
●
AN3356: Interfacing to the VD5377 optical navigation device (018567)
●
AN3217: Interfacing to the VD5376 optical navigation device (017529)
October 2011
VD5376/VD5377 optical finger navigation testing
Doc ID 018955 Rev 1
www.BDTIC.com/ST
AN3419
Application note
1/16
www.st.com

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Summary of Contents for ST VD5376

  • Page 1 Application note VD5376/VD5377 optical finger navigation testing Introduction This document gives a non-exhaustive list of tests which may be run on the ST VD5376/VD5377 optical finger navigation (OFN) devices. Initialization The initialization setup depends on the customer application (for example, automatic or manual power mode, direct 1v8 drive or Vtop supply, CPI setting, X/Y direction and so on).
  • Page 2 Navigation AN3419 Navigation This chapter describes the navigation tests that can be performed on the VD5376/VD5477 sensors. XY table navigation Using a mechanical setup gives accurate navigation results of how well the module navigates at various speeds and over various surfaces.
  • Page 3 Figure 8 ) considered acceptable OFN navigation (plots below were done at 4ips). Figure 5. OFN good navigation Figure 6. OFN good navigation Figure 7. OFN bad navigation Figure 8. OFN bad navigation Doc ID 018955 Rev 1 3/16 www.BDTIC.com/ST...
  • Page 4 CPI value. Figure 7 Figure 8 shows glitchy navigation while the navigation in drifts, is too small and does not complete the full circle. These errors cannot be ‘fixed’ by register settings. 4/16 Doc ID 018955 Rev 1 www.BDTIC.com/ST...
  • Page 5 The image below shows good finger navigation. The module was tested by manually Figure 9 swiping a finger across the sensor. One swipe in each direction ( Figure 9. Manual finger swipes - good navigation Doc ID 018955 Rev 1 5/16 www.BDTIC.com/ST...
  • Page 6 Navigation AN3419 Figure 10. Manual finger swipes - bad navigation 6/16 Doc ID 018955 Rev 1 www.BDTIC.com/ST...
  • Page 7 AN3419 Navigation Figure 11. Manual Swipes - bad (jittery) navigation Doc ID 018955 Rev 1 7/16 www.BDTIC.com/ST...
  • Page 8 Mode Max exposure Run fast Run medium Run Slow Powerdown 40uA Automatic power management mode should not be used with VD5376 in applications with more than one device on the I C bus. 8/16 Doc ID 018955 Rev 1 www.BDTIC.com/ST...
  • Page 9 AN3418: VD5377 OFN high speed imaging system (018952) – Image download over I C is very slow on the VD5376 (0.5fps), this is because of the auto increment I C read function. This can be disabled on the VD5377, enabling a much faster image download.
  • Page 10 OFN module for this test mode. See application notes AN3417 and AN3418 for more details. In both Figure 14 Figure 15 , the image download application shows Features, MEP and exposure. Figure 14. VD5377 ST image download application (1x optics) 10/16 Doc ID 018955 Rev 1 www.BDTIC.com/ST...
  • Page 11 AN3419 Images Figure 15. VD5376 ST image download application (0.75x optics) Doc ID 018955 Rev 1 11/16 www.BDTIC.com/ST...
  • Page 12 ), but there is some misalignment with the optics and the LED, so we only see half the image. ® a. Blu-Tack is an adhesive tack product and is a registered trademark of Bostik. 12/16 Doc ID 018955 Rev 1 www.BDTIC.com/ST...
  • Page 13 AN3419 Images Figure 18. Blu-Tack, flat centred image - good Figure 19. Fingerprint - good Figure 18 shows a good image of Blu-Tack. Figure 19 shows a good image of a fingerprint. Doc ID 018955 Rev 1 13/16 www.BDTIC.com/ST...

  • Page 14: Other Factors

    A 150W halogen light source (with IR filter removed) and light pipe is used to illuminate the module. The light pipe is held approximately 5cm away. It is important to test navigation with both slow and fast movements. For the VD5376, the application note AN3217: Interfacing to the VD5376 optical navigation device (017529) describes how to improve sunlight navigation.

  • Page 15: Revision History

    AN3419 Revision history Revision history Table 3. Revision history Date Revision Changes 04-Oct-2011 Initial release. Doc ID 018955 Rev 1 15/16 www.BDTIC.com/ST...
  • Page 16 No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein.

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