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Allegro acs756 current sensor for arducopter

Posted by Alexey Kozin on November 7, 2012 at 11:00am

allegro current sensor

The sensor is galvanically isolated from the circuit, but in contrast to the classical current sensor shows not only the battery discharge and charge it (eg energy recovery in airplanes)
but because of this, at zero current output, exactly half the supply voltage (for classical sensors autopilot 0) ie 2.5 volts.

to correct this misunderstanding to change firmware code

defines.h change

#define CURRENT_AMPS(x) ((x*(g.input_voltage/1024.0))-g.curr_amps_offset)*g.curr_amp_per_volt

parameters.pde add

    // @Param: AMP_OFFSET
    // @DisplayName: current sensor zero calibration
    // @Description: in volts
    GSCALAR(curr_amps_offset,      "AMP_OFFSET", CURR_AMPS_OFFSET),

parameters.h add

k_param_curr_amps_offset = 193,

      AP_Float        curr_amps_offset;

//#ifndef CURR_AMPS_OFFSET
# define CURR_AMPS_OFFSET               0.0
//#endif

archive with source and HEX file for quaid "x" APM2 here

arducopter, current, sensor

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Comments

daniel garrow October 6, 2017 at 11:18pm

my X8 can pull up to 531 amps so can I even use a current sensor?
Alexey Kozin February 5, 2014 at 10:04am

Thanks!!!!
Alexey Kozin February 1, 2014 at 8:31am

somebody ask Randy include this in the official firmware
Alexey Kozin February 21, 2013 at 10:22am

I offered Randy enable this setting in the official firmware
he either missed my post, or ignored.
try someone to write about it again to Randy

ps

and arduplane this parameter has made.
Alexey Kozin November 20, 2012 at 11:28pm

many thanks Andrew,
unit of measurement offset in volts, the range of values from 0.00 to 5.00
by the way this applies to standard sensors to calibrate the zero value
Developer

Andrew Tridgell November 20, 2012 at 6:34pm

Thanks Alexey! I've added your change in for the next release.
Alexey Kozin November 13, 2012 at 10:43pm

dont calculate cf and rf

it may be

rf = 1KOm - 3 KOm

cf = 1 - 4.7 microfarads

rfcf filter needed for accuracy measurement of "average current"
Rick Eis November 13, 2012 at 9:53pm

Alexey,

Awesome job on the voltage regulator!

So did you build as in the schematic posted above and if so, what did you use for Cf and Rf ?

Rick
Alexey Kozin November 8, 2012 at 11:20am

new value amp_offset used for tune input voltage on current sensor port "a1" with "zero current" allegro sensor with "zero current" have about 2,5 volts output

amp_per_volt used too, for calibrate sensivity

for +-100A allegro chip it is 40.0

for +-50A allegro chip it is 20.0
Andy November 8, 2012 at 6:04am

so the only vlaue that we have to determine is the "g.curr_amp_per_volt" am I right?