Use unit prefix only instead of full unit

[laborleben]

instead set_voltage(self, channel, value, unit='mV') use set_voltage(self, channel, value, unit='m').

Makes things easier when comes to abstraction. We can also do some unit conversion based on a new class that we can put inside utils. The conversion is then based on a dict like that one: _prefix = {'y': 1e-24, # yocto 'z': 1e-21, # zepto 'a': 1e-18, # atto 'f': 1e-15, # femto 'p': 1e-12, # pico 'n': 1e-9, # nano 'u': 1e-6, # micro 'm': 1e-3, # mili 'c': 1e-2, # centi 'd': 1e-1, # deci 'k': 1e3, # kilo 'M': 1e6, # mega 'G': 1e9, # giga 'T': 1e12, # tera 'P': 1e15, # peta 'E': 1e18, # exa 'Z': 1e21, # zetta 'Y': 1e24, # yotta } also check http://stackoverflow.com/questions/10969759/python-library-to-convert-between-si-unit-prefixes.

[laborleben]

We can stay compatible to the old interface by just evaluating the first char.

[themperek]

full ack

[DavidLP]

I would not add a unit feature at all. It should be understood that all is in SI base units. Adding a e.g. e-3 at the base unit should be no issue. Otherwise one can only understand any value with the unit string. At least I would make this a not mandatory API feature, but an optional way to define values. And the standard unit should be SI base units.

[laborleben]

depends, actually I can live without that feature. Others are using it. However, implementing the conversion into every function is a waste of code. It can also be, that a conversion is needed for a DAC or ADC (wich is not using SI base unit).

[DavidLP]

A conversion for a ADC/DAC? What is that? ADC/DAC is just a value and no unit at all.

[themperek]

You do not want to thing what is 1.273V in DAC units. And calibration on top.

On Sat, Mar 14, 2015 at 6:15 PM, D.-L.Pohl notifications@github.com wrote:

A conversion for a ADC/DAC? What is that? ADC/DAC is just a value and no unit at all.

— Reply to this email directly or view it on GitHub https://github.com/SiLab-Bonn/basil/issues/10#issuecomment-80602245.

[DavidLP]

Now we are talking about calibration and not units ;-). But for calibration data it is much better to have the SI base units only, otherwise some calibrations will be in mV, some in V... To say set_voltage(1.273) is what I would prefer. How this is translated to a DAC value is irrelevant.

[themperek]

One does not go against other we assume we use default Si unit as default so e-3 etc will work. And we have optional unit parameter. Would this work? Does not break current situation.

[themperek]

http://pint.readthedocs.io/

[themperek]

We do this?