[C++] NXT Light sensor defective or C++ driver faulty?[SOLVED]


#1

hi,
running the NXT sensor example program sensors_nxt.c I get Light sensor readings just between about 2100…2600,
either if I have no object targeted or white or black or red or blue or anything closely in front.
I personally had expected values of 0…1023 for it.

(remark:
I disabled the color sensor as I don’t have one availble FTM, rest as decribed)
Nonetheless, USS and touch sensor are both working fine.

Is that supposed to be a correct light sensor reading though quite as designed by BrickPi3 ?

or is there perhaps a 12bit ADC active instead of 10bit?


#2

The BrickPi3 does indeed have 12-bit ADCs instead of 10-bit. The raw value range is 0-4095.


#3

ok,
but about the observed range of just 2100-2600…:
is that correct quite as expected and reproducable also for your NXT Light Sensor?


#4

Using the NXT light sensor in reflected mode (LED on), I see values from about 1700 (reflecting off a white surface) to about 3300 (pointed into a dark space).


#5

ok,
reproducable to me by sensors_nxt.c max. 1900-3000 ,
== about 475 - 750 in 10bit ADC.

So if that’s what was expected, then it’s fine!