Re: [Paparazzi-devel] Aspirin I2C Only Wiring

[Christophe De Wagter]

Dear Simon,

I updated the yapa page a bit: http://paparazzi.enac.fr/wiki/Yapa#5_Volt_-_Molex

Now to power your aspirin (or other sensitive imu)

1) I personally prefer the i2c-only carrier board with extra linear power supply. 

2) you can use the 5Volt [http://paparazzi.enac.fr/wiki/Image:Yapa_v2_5volt.jpg]

3) while theoretically not being ideal: in practice powering the aspirin with 3.3volt also works well (only a few millivolt dropout)

4) After checking all datasheet it looks like the imu can also be powered directly from any 2-cell or 3-cell lipo safely. (Aspirin: 3.6mA + 0.4mA + 0.8uA = 6mA. lp2992 regulator on aspirin: max voltage input: 16Volt. Power dissipation at 3-cell LiPo: 0.05 Watt = no problem) 

 I will check option 4 the next days to find the best (easy+good) way to power the aspirin on any twog/tiny/yapa. I expect that for the latter solution a RC filter in the power line is useful to cope with VBat fluctuations caused by motor controllers etc...

-Christophe 

On Thu, Nov 24, 2011 at 8:13 PM, Simon Wilks <address@hidden> wrote:

Hi Christophe,

I am using a YAPA V2.0 and I will power the servos separately. 

So when looking at this: http://paparazzi.enac.fr/wiki/Image:Aspirin_IMU_documented.jpg I would connect:

Aspirin SCK and Aspirin SCL -> YAPA I2C-SCL

Aspirin MOSI and Aspirin SDA -> YAPA I2C-SDA

Aspirin GND and Aspirin MISO -> YAPA I2C-GND 

Aspirin ACC_CS -> YAPA GPS-3.3V

Aspirin 5.6V -> YAPA ???

Is this correct? Where can I tap 5V from on the YAPA V2?

The carrier PCB could be interesting if I can get the Aspirin off the current carrier board. Are they available?

Thanks,

Simon

On Thu, Nov 24, 2011 at 7:30 PM, Christophe De Wagter <address@hidden> wrote:

The aspirin expects anything from 3.6 to 7 volt to be powered. The "cleaner" the bettter: (less ripples, variations, emi, emc, emd, ...)

e.g.:

on Lisa-L use the linear dcdc 6.5V analog supply 

on the tiny/twog ... probably the less bad solution is to power it from the 5V and make sure your servo's are not powered with the onboard 5V. A big low ESR capacitor added very close to the aspirin and maybe even a 1Ohm resistor in the VCC wire towards the aspirin can also help. 

There is also a breakout board for this if you don't mind ordering a pcb.

-Christophe 

On Thu, Nov 24, 2011 at 4:41 PM, Simon Wilks <address@hidden> wrote:

Hi,

The wiki page for the Aspirin IMU (http://paparazzi.enac.fr/wiki/Inertial_Measurement_Units#Aspirin_IMU) states:

Connect Aspirin-SCK and aspirin-SCL to the I2C-SCL, aspirin-mosi and aspirin-SDA to I2C-SDA, Vcc to 5V (preferably linear), aspirin-gnd and aspirin-miso to GND, and aspirin-CS to 3.3V.

The only part I don't understand is what I need to do for Vcc to 5V (preferably linear). 

Thanks

Simon

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