[Paparazzi-devel] Fwd: Twog and I2C.

[Helge Walle]

Hi again,

As a follow up to my own mail below:

Of course the reading frequency of the imu is controlled by PERIODIC_FREQUENCY, sorry I was just looking past that.

I then found that when using the ppzuav subsystem. the autopilot is polling for a magnetometer, which the SEN-10121 imu does not have. This is what filled the I2C bus. So when I stopped the polling for a mag, there is much idle time on the bus.

Thanks,

Helge.

---------- Forwarded message ----------
From: Helge Walle <address@hidden>
Date: 2015-05-30 18:45 GMT+02:00
Subject: Twog and I2C.
To: "address@hidden" <address@hidden>

Hi,

I am testing my Twog with an airspeed indicator consisting of two MS5611 pressure sensors. Results are promising, but sometimes I don't get data from one or both of the MS5611s after power cycling the system. A repeated power cycle normally cures this. When both barometers get running, they run consistently.

The Sparkfun SEN-10121 IMU seems to work fine every time, and I have no problems with Auto2 flight.
I use   <subsystem name="imu"           type="ppzuav"/> in my airframe file.

I am on Paparazzi version 5.4 and use my own DIY twin-barometer module.

I looked at the I2C bus with my logic analyzer, and it seemed the protocol was almost filled with data, leaving almost no idle time at all. Excluding the barometers module showed that the IMU packs the I2C protocol with data. The SEN-10121 has ITG3200 gyro and ADXL345 accelerometer.

I increased the clock frequency from 37500Hz to 125000Hz with these defines in my airframe file:
<define name="I2C0_SCLL"         value="60"/>
<define name="I2C0_SCLH"         value="60"/>

Is this the correct way to control the frequency? Please advise.

I would like to be able to control the reading cycle frequency of the sensors on the IMU board, How should I do this?

Thanks,

Helge.