Hey all,
First post on here so firstly hello to all, already found the chat link very helpful.
I'm building a circuit 'tilt sensor' which displays 20 LEDs driven by a pair of LM3914s. I'm using a freescale MMA7361 stamp which has a selectable +/- 1.5 and 6 g output.
Here lies the problem.
I'm only interested in measuring +/- 20 degrees from the horizontal. Reading the data sheet, it shows there is a 800mV change, per 'g' and 1g is equivelent to 90 degree's. This would mean 800mV/90deg would give me my mV change per degree moved, ie 8.8mV per degree moved/displaced.
When I put the output through my oscilloscope, the trace is unstable. The trace p-p is about 30mV therefore as 1 degree should be circa 9mV, I'm unable to display any degree of acuracy beyond 3-4 degrees.
Any help, advice welcome...maybe you've had the same problem...maybe its noise or are these 7361 chips that bad?? The Chip has conditioning so presume its not that...
Over to you!
First post on here so firstly hello to all, already found the chat link very helpful.
I'm building a circuit 'tilt sensor' which displays 20 LEDs driven by a pair of LM3914s. I'm using a freescale MMA7361 stamp which has a selectable +/- 1.5 and 6 g output.
Here lies the problem.
I'm only interested in measuring +/- 20 degrees from the horizontal. Reading the data sheet, it shows there is a 800mV change, per 'g' and 1g is equivelent to 90 degree's. This would mean 800mV/90deg would give me my mV change per degree moved, ie 8.8mV per degree moved/displaced.
When I put the output through my oscilloscope, the trace is unstable. The trace p-p is about 30mV therefore as 1 degree should be circa 9mV, I'm unable to display any degree of acuracy beyond 3-4 degrees.
Any help, advice welcome...maybe you've had the same problem...maybe its noise or are these 7361 chips that bad?? The Chip has conditioning so presume its not that...
Over to you!
Last edited: