I am using an analog pin on an arduino nano 3.0 to read a gyro (IXZ-500).
I am trying to optimise the reference voltage in order to get the resting voltage of the gyro into the middle of the analog pin's 1024 value digital range.
The resting (zero-rate) value of the gyro is 1.35v so I assume the best reference value for the arduino's AREF pin is 2.7v (1.35v range for one direction of angular rotation and 1.35v range for the opposite direction).
However, the reference voltage supplied by the IXZ-500 is also 1.35v.
Can anyone suggest the simplest way of getting the arduino, through code or hardware, the 2.7v reference voltage it needs for this task?
You didn't state the accuracy you require (including drift).
There are a variety of references that are 3V. Use the parts selectors at Linear Tech,
Analog Devices and TI.
You can also trim references using resistors. You need to be careful of the resistor
accuracy and drift otherwise your reference will no longer be a reference. I would
not use a potentiometer. Pick fixed resistors and then calibrate if necessary.
You didn't state the accuracy you require (including drift).
I assume you mean accuracy and drift of the reference voltage?
The 'references' you refer to, are they essentially precision voltage regulators? So I could take the 3.3v off the arduino and reduce it through a combination of these regulators and some fine-tuning with resistors?
How do you calculate the correct resistor value for the voltage reduction? Does something like (V1-V2)/I = R make sense where V1 is the initial voltage and V2 is the desired lower voltage?
The accuracy and drift of the reference voltage is one part of the
measurement accuracy and drift. The A/D converter and sensor+signal
conditioning are the other parts. Placing a reference
with 5ppm/degC drift on an A/D with 1000ppm/degC drift won't
help the drift accuracy and will unnecessarily increase your cost.
You don't want to use a divider. This will decrease the accuracy
of the reference. The companies that make references make adjustable
references. In the datasheets will be the application circuits and
calculations. Look for "shunt references" at Linear Technology,
Analog Devices, Texas Instruments or National Semiconductor.
I would start with Linear Technology.