On the MMA7361 accelerometer, the guide says the static acceleration when kept flat with standard 3.3v input, should read out the following:
x axis -> 1.65 v
y axis -> 1.65 v
z axis -> 2.45 v
The results i am getting are like this:
x axis -> 1 v
y axis -> 1 v
z axis -> 1.2 v
Anyone know why this is happening, and if/how i can fix this?
--
Thanks Yogesh
Did you measure to be sure your 3.3V power is 3.3V at the chip's power and ground pins?
Are your sure your voltmeter is accurate? I would have expected more than one or two digits.
Note: The datasheet says that at 25°C and 3.3V input the 0G outputs should be between 1.485 and 1.815.
We connected it to the arduino duemilanove board, we measured the input voltage around 3.3v
The voltmeter is accurate, however it is analog..
Analog meter. That's why.
Analog meter ohms-per-volt around 10k to 20k, Digital meter input impedance 10M to 100M.
Analog meter can't measure an voltage accurately if its greater than a couple of hundred ohms or so output impedance.
Gotcha, i'll get a digital meter and check.
But, if that's is the problem then why does the 3.3v measure accurately?
yfegade:
Gotcha, i'll get a digital meter and check.But, if that's is the problem then why does the 3.3v measure accurately?
Low output impedance.
Typical voltage regulators manage output impedances well under an ohm. Its basically their function to be a voltage source.
I used a digital meter and it started giving me proper readings, thanks for the assistance