Vernier Sensor

[ccorrea]

Hi everybody!!

Anyone know what IC using Vernier sensors (conductivity or other), I think they use some kind of I2C IC. I need to know which one, in order to try to comunicate with them.

Thganks and best regards

Christian

[WalrusBrigade]

I too have been trying to figure out how to access some vernier sensors in lejos. I've got the adapter, but all of the support is for LabView, RobotC or NXT-G. I'm trying to turn 4 force sensors into a force plate, and was going to use the NXT to do the processing and output. But trying to code sensors is a bit beyond my ability. So if anyone can answer this question and already has a way to communicate with them, I would love to hear what it is.

Christian, if you can figure this out would you please post the result so I could try your code. Thanks.

Martin

[skoehler]

I too have been trying to figure out how to access some vernier sensors in lejos. I've got the adapter, but all of the support is for LabView, RobotC or NXT-G. I'm trying to turn 4 force sensors into a force plate, and was going to use the NXT to do the processing and output. But trying to code sensors is a bit beyond my ability. So if anyone can answer this question and already has a way to communicate with them, I would love to hear what it is.

Christian, if you can figure this out would you please post the result so I could try your code. Thanks.

You can use the methods of the SensorPort to do I2C I/O. I think it's very much like in RobotC, once you get the idea of how to translate RobotC command into leJOS calls.

[WalrusBrigade]

Thanks!! I'm not really familiar with RobotC . . . or any C for that matter. I just brought it up because the support for the NXT adapter has RobotC in it. Still, I can fiddle around with SensorPort and hopefully will figure out how to get the data out. By the looks of it I can use the .readRawValue() method and do some processing after the fact. My only concern now is figure out how to configure the sensor properly. Again, thanks for pointing me in the right direction.

[skoehler]

Thanks!! I'm not really familiar with RobotC . . . or any C for that matter. I just brought it up because the support for the NXT adapter has RobotC in it. Still, I can fiddle around with SensorPort and hopefully will figure out how to get the data out. By the looks of it I can use the .readRawValue() method and do some processing after the fact. My only concern now is figure out how to configure the sensor properly. Again, thanks for pointing me in the right direction.

readRawValue is for analog sensors only. For I2C, you have to use other method. Take a look at the source of the I2CSensor class.

[sojkic]

Hi,
do you know how get values from dual-range force sensor (Vernier)? I work in Java and I use nxt unit with Vernier nxt adapter. Can you help me, please? I´m sorry my English is bad.

[skoehler]

Please tty SensorPort.S1.readRawValue()
You will probably have to calibrate the sensor yourself.

[sojkic]

Please tty SensorPort.S1.readRawValue()
You will probably have to calibrate the sensor yourself.

This method SensorPort.S1.readRawValue() return value -1 and a I don´t know why.

[skoehler]

You probably to call SensorPort.S1.setTypeAndMode once before readRawValue will work.
SensorConstants.MODE_RAW is probably the right mode. I'm not sure about the type. Try SensorConstants.TYPE_LIGHT_ACTIVE and TYPE_LIGHT_INACTIVE.

[sojkic]

You probably to call SensorPort.S1.setTypeAndMode once before readRawValue will work.
SensorConstants.MODE_RAW is probably the right mode. I'm not sure about the type. Try SensorConstants.TYPE_LIGHT_ACTIVE and TYPE_LIGHT_INACTIVE.

Excellent... The method return some value now, but Do you know how it calibrate, please? Thank you, very much.

[skoehler]

Apply a known force, write down the value. Apply another known force, write down the second value. Now perform linear interpolation. Or, even better, apply a third known force, and write down the value. Now look, whether linear interpolation is actually the correct method.

[sojkic]

Apply a known force, write down the value. Apply another known force, write down the second value. Now perform linear interpolation. Or, even better, apply a third known force, and write down the value. Now look, whether linear interpolation is actually the correct method.

I´m sorry, but why linear interpolation? This method return value in the unit NXT 555-556. This is mN??? I am tried take first value and writed to variableA and then I used variableB = (variableA - variableB); variableB is the second measured value. It is probably wrong, right? Maybe this are bad questions, i´m sorry. Thank you for your help.

[skoehler]

readRawValue() returns the value of the ADC. it's neither Newton-meters or any other unit that has a name.

The r1 and r2 the two raw values and let f1 and f2 be the corresponding known forces.
Then f = (r-r1)*(f2-f1)/(r2-r1)+f1 where r is the current raw value and f is the current force.

That's pretty basic linear interpolation between two known points (r1,f1) and (r2,f2).

[sojkic]

readRawValue() returns the value of the ADC. it's neither Newton-meters or any other unit that has a name.

The r1 and r2 the two raw values and let f1 and f2 be the corresponding known forces.
Then f = (r-r1)*(f2-f1)/(r2-r1)+f1 where r is the current raw value and f is the current force.

That's pretty basic linear interpolation between two known points (r1,f1) and (r2,f2).

Yes, I found this pattern, but I didn´t know what to put into the pattern. Where do I get the value of f? r is value from method readRawValue()? Thank you very much for your help.

[skoehler]

f is the value you compute. What you actually need are r, r1, r2, f1, f2. And yes, r is the value returned by readRawValue().