1 / 16

CY3236A-PIRMOTION: Pyroelectric Infrared (PIR) Motion Detection Evaluation Kit (EVK)

CY3236A-PIRMOTION: Pyroelectric Infrared (PIR) Motion Detection Evaluation Kit (EVK). Agenda. PIR Theory PIR Motion Detection—The PSoC Way. PIR Theory. PIR Theory - Basics. Humans at normal body temperature radiate most strongly in the infrared spectrum at an approximate wavelength of 10uM

jaime-tillman
Download Presentation

CY3236A-PIRMOTION: Pyroelectric Infrared (PIR) Motion Detection Evaluation Kit (EVK)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CY3236A-PIRMOTION:Pyroelectric Infrared(PIR) Motion Detection EvaluationKit (EVK)

  2. Agenda • PIR Theory • PIR Motion Detection—The PSoC Way

  3. PIR Theory

  4. PIR Theory - Basics • Humans at normal body temperature radiate most strongly in the infrared spectrum at an approximate wavelength of 10uM • To detect this signal, a transducer is required that converts the infrared signal to current or voltage

  5. PIR Theory – PIR Sensors • A PIR sensor is made of ceramic material that generates surface charge when exposed to infrared radiation • As the amount of radiation increases, the surface charge generated increases • A FET is used to buffer this signal

  6. PIR Theory – PIR Sensors • As the sensor is sensitive to a wide range of radiation, a filter window is added • This window limits the infrared rays falling on the ceramic pickup to 8um-14um range • Also, a resistor is added to the source of the FET to convert the charge to voltage Filter Window Ceramic Substrate

  7. PIR Theory – PIR Sensors • The output of the sensor is the function of infrared radiation • But the output is also affected by vibration, radio interference, sunlight etc What is the solution? Filter Window Ceramic Substrate

  8. PIR Theory – PIR Sensors • Dual Sensors are used • Both sensors are connected out of phase such that any excitation that is common to both the sensors cancel out • A body passing before the sensors excites first one and then the other sensor Two Sensors connected out of phase Physical Construction of a dual sensor

  9. PIR Theory – Fresnel Lens • To improve the range and detection angle, Fresnel Lens are used • A Fresnel lens is a plano convex lens that has been collapsed on itself to form a flat lens that retains its optical characteristics, but is thinner and has lesser absorption losses

  10. PIR Theory – Fresnel Lens • There are many types of Fresnel Lens available, each having a different angle of coverage, focal length etc

  11. PIR Theory – Detection • When an object moves in front of the sensor, the dual elements are excited one after other • The resultant output is a +ve signal followed by a –ve signal

  12. PIR Theory – Detection • The signal is first amplified using an amplifier and then fed to a comparator • The comparator produces an output when the sensor detects a movement • This comparator output can be further processed to control electrical loads

  13. PIR Motion Detection Applications • Automatic Lighting Controls • Automatic Door Openers • Security Systems • Activating Wireless Cameras

  14. PIR Motion Detection—The PSoC Way

  15. PIR Detection – The PSoC Way • The Amplifier is implemented in 2 stages with capacitive coupling between stages • ADC measures the output of amplifier stage

  16. PIR Detection – The PSoC Way • Digital High Pass Filter and Decision logic in firmware • All Hardware and Firmware implemented in One PSoC Device Refer to AN2105 on www.cypress.com/designresources

More Related