Digilent CMPS2 with MyRio

[adanali]

Hi everybody;

I have bought Digilent CMPS2 compass module in order to use it with MyRio 1900. I have watched NI myRIO- Compass demo LabVIEW project video (https://www.youtube.com/watch?v=bWew4fHWVKo) which is related to CMPS compass module. But I couldn't find the connection diagram of CMPS2 compass module for MyRio. When I run the software located in "Part II - NI myRIO Mechatronics Kit/Compass demo", I have taken error message in Labview. Could you please help me about the connection diagram between the Digilent CMPS2 compass module and MyRio? I couldn't find any document for CMPS2 compass module about the wiring. 

Thanks a lot... 

[Bob_Schor]

The Good News is you've found two Ed Doering videos addressing the Digilent CMPS with myRIO.  Is this the same Digilent board you are using?  If not, you may need to make some small changes to the Wiring of the Board to myRIO, and also some minor Software changes (for example, the Doering video uses an I²C Board -- is your board I²C or SPI?  {SPI is different, both in wiring and in programming).

If you are unsure about the wiring, and Digilent can't supply you with the documentation, take a close look at the Board and note the information about the Chip.  Is it the Honeywell HMC5883L shown in the videos?  Then the wiring should be the same.

Bob Schor

[adanali]

Hi Bob;

First of all, thanks a lot for your kind interest. While the Digilent PmodCMPS has Honeywell HMC5883L three-axis compass, the Digilent  PmodCMPS2 has Memsic's MMC34160PJ. You can find the demonstration setup below for compass connected to NI myRIO MXP Connector A.

The problem is that while Pmod CMPS has J2/DRDY output (Data ready), there isn't J2/DRDY output on Pmod CMPS2. That's why, I don't know what to connect instead of the J2/DRDY output???

  

I guess, I should do some modifications on previous software, but I don't any idea about it. In addition that I don't know jumpers position about leaving both jumpers JP1 and JP2 disconnected or connected???

As you mentioned, both sensors (Pmod CMPS and Pmod CMPS2) use I2C-bus serial communications.  

Best Regards...

 

[Bob_Schor]

OK, you have a different Chip and it behaves (slightly) differently.  Now you are getting into Electrical Engineering (EE) territory.  The Chip manufacturer has a 14-page Data Sheet that explains how to use the Chip, how to set it up to take readings, all the steps you need to do to program the I²C circuitry.  The basic steps are the same as for the original Chip (is that still available?  If so, and you used it, you could just follow the wiring and logic laid out by the earlier Video), but (as you note) there doesn't seem to be an Interrupt line (though I thought I saw something called "Int" on one of the figure ...).

I'm not an Engineer (Electrical, or otherwise), so I won't give you advice, other than Read the DataSheet, and ask your Engineering colleagues for assistance/interpretation if you need it, though the sections at the end do seem to spell out the steps you need to take to get readings.

Let us know if you are successful -- it may well help the next person who encounters this Chip.

Bob Schor