March 5, 2009
C, C++, C#
Broklyn Poly (now: NYU)
Kiev Polytechnic Institute
PIC microcontrollers, programming
RC aircrafts, quadrocopter
about a year ago
Does anybody know at what frequency the Gyro sensing masses oscillate? I checked the datasheet, but did not find this data. In the past the ST’s gyro were not good for quads and helis due to the low frequency of oscillation so most of the control boards use Invensense sensors that have 27 KHz - 33 KHz oscillation rate for gyros.
I am curious whether this sensor is applicable to quads and helis.
about 3 years ago
First, the LSB is 0.1 uT, so to convert the result to micro-Tesla you need to multiply captured value by 0.1.
Second, as i noticed, this magnetometer has a huge offset (at least the one that I got) - for example, when I rotate the magnetometer the X value changes in the range of about 270 uT to 200 uT, while the proper range should be from about 35uT to -35uT. Looks like I need to load the x-offset register with something like -2350 (note: the user offset is applied to the raw measurement, which is calculated with LSB=0.1uT).
Why do you put the pull-up resistors for SDA/SCL lines on the breakout boards? It is rather easy to pull up these lines on the breadboard or in a custom board, but this practice makes it really difficult to attach several sensors to the same I2C bus.
I was trying for some time to make this breakout board and the one for MPU-6050 to work on the same bus and was getting strange errors until I noticed that each of the breakout board includes the pull-up resistors (4.7 KOhm for MAG-3110 and 2.5 KOhmn on MPU-6050), which put the bus out of specs.
about 3 years ago
Oh, it would have been a beautiful board IF Sparkfun guys break out the interrupt lines for each of the sensors - it makes programming MCU soooo much nicer without wasting time to re-query each of the sensors to find out when it is ready.
about 5 years ago
You would make a much, much better board if you bring our the DRDY pin to the header - there is a good reason that Honeywell decided to bring out the RDY bit (SR0 of the Status register) to a separate pin and it is pity that you did not do the same!
Having the DRDY pin available would make asynchronous (interrupt-driven) reading data from this magnetometer much, much easier; for now it is quite cumbersome…
The datasheet says that the I2C lines of this device are nominal 3.3V… I would appreciate an advise or share comments regarding interfacing this magnetometer with 5V dsPIC MCU.
No public wish lists :(
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