OLLYDOTDEV
commented
4 years ago PIR or passive infrared sensor
(note PIR do not work well in a hot environment where the ambient temperature is the same as people's this is one of the limitations of the functionality)
is a sensor that is used to detecting people.
for this project birdseye I have decided to go with the HC-SR501
- it is great as it has a long Sensing range: Max 7 m.
- it does have an Adjustable delay before triggering but this will not be used as I will be doing this in software.
- Input voltage range from 4.5 to 5v which is great as that is with my ROMS operational voltage
- has an Angle Sensor around 100 degrees FOV
the other competitor was the HC-SR505 it has a smaller range and in theory the same cone angle but in practice, it is greater. see here
added need header to ROMS pcb to allow for PIR sensor connection
here is my wire up for testing
the code for this can be found on Github here
both of these sensor fall under what is called a 1x1 pixel. as in short how they work are they take the average ambient infrared input and then checking if there has been a change in temp in the same place. with the sensor that has only one LARGE pixel you can get more pixel 4x4 8x8 16x16 etc that in turn allows you to see images and make out objects but there have been much research done and it has can be seen that in very few cases are the extra pixels properly utilized or give any additional reliability, therefore, they were not considered as a sensor for this project. as typically they more commonly used as bad thermal cameras (high pixel count)
As user I need more than one forum of a sensor on ROMS as a backup for https://github.com/OLLYDOTDEV/Project-Birdseye-DTX-2020/issues/12 so I can be sure that the information protection system activates