Hi!
I have bought a “Grove - PIR Motion Sensor”. I have got problem to change a sensor range. I want to detect object to maximum 1 meter. Over this value objects should be ignored.
I removed resistor R4 and I solder potentiometr 2MOhm. The foto resistor is not connected.
How to calibrate the sensor? What value should be of R4 resistor for fixed range 1 meter?
Thanks for help!
Hi there,
I tried it and succeeded.and I follow the process below：
1.Remove the R13 from the PCB board；
2.Add a potentiometer to the corresponding position on the PCB board(As shown below)
3.Adjustment potentiometer
Initially estimated for a fixed range of 1 m, the R13 resistance should be 0.188MΩ
1 Like
I want to do the same thing but limit the range even more (preferably a few centimeters) how do you determine the value of the resistance beforehand?
Hi there,
And Welcome Here,
So why not switch to the mmWave Sensor.? it can do very accurate measurement’s in that range, Check out the Wiki , for it and there are some examples and I have a demo with code as well , showing the PC app and the Xiao measuring Centimeters and Millimeters, and it detects moving object also. 
HTH
GL 
PJ 
or this device… i think it is basicly the same
or this device…. it measures real close… like too close to me… what is your location.. i would send you my… i have no use for it… i thought it was higher range
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The issue is that I need it for a school project. That’s why I’m limited to only a list of sensors I’m allowed to use. Also I only need a yes or no output from the sensor that’s why a more precise ultrasonic sensor isn’t the most efficient option.
2 Likes
are you saying you have to use the grove unit?
I am assuming you saw the OP used a pot to trim the measurement? i would say go that route or use a digital pot
according to this WiKi the pot is the way to go for the adjustment
on the seeed website, each product page has a tab called WiKi and learn… this tab will lead you to more information and a link to the WiKi.. or you can search the Wiki directly… that can be accessed by the seeed main page, support tab (where forum and discord are) FAQ and Wiki tab… i am going to ask them to move this out one layer to be easier to find
maybe you can ask your teacher for permission… they may like your resourcefulness
are you in the US? probably not… maybe I can get seeed to send you some gear
Hi there,
So you can maybe set the Operating Voltage from 5Vdc to 3.3Vdc if possible that will also lower the detection distance also. Keep that in mind too. So if the POT doesn’t get you low enough, drop the VCC to 3.3v see if it works. 
HTH
GL PJ
1 Like
great idea… i guess it depends on the MCU unit… if it is arduino it should be 5v… but if XAIO it would be 3v3 powered grove connectors… an important distinction to keep in mind when troublshooting grove modules.. Great Point PJ (GPPJ) or (GPPJG)
might be able to splice a pot onto the grove red wire, elegant solution