[PD-dev] making a libusb object (expanding on [hid] toolkit)

[Christian Klippel]

hi all,

Am Sonntag 22 Januar 2006 20:45 schrieb B. Bogart:
> Hey all,
>
[...snip...]
>
> An approach would be to list all the common atributes:
>
> * analog in
> * analog out
> * digital in
> * digital out
> * PWM out (maybe?)
>
> based on this we could have three objects:
>
> [analog] [digital] [pwm]
>

you can drop [pwm] ... it is basically the same as [analog] .....
that the _real_ output is a pwm signal (whose average equals to an analogue dc 
voltage) is a matter of the used chip .....

> Can we simulraneously read and write to any of these devices? (that
> would be a nice feature)
>

usually yes .....

> You send the message [set 0 0.5< to set the first analog output of the
> device to half way up its full range. [set 1 1< would set the second
> analog output to its full range (5v).
>
> Maybe the analog out has modes for say, internal polling, or external
> polling, and for the range of pins to poll. [poll internal< [poll
> external<, [range 0 5< polls the first to the 6th outputs)
>

you mean analogue in, right? at least for the multio, the next firmware will 
have the option to turn off the auto-update of thechannel(s). polling is 
alway possible.

> The messages we get from the analog object would be something like:
>
> [0 0.5<   # first input is 2.5v
>
> So we just need to [route 0 1 2 3 4 5 6] or some more complex method for
> an unknown dynamic number of inputs.
>
> digital would act the same, except the argument would be a 0/1 rather
> than a float to turn pins on and off.
>

right ......

> [pwm]
>
> would have only an input, and we set it with [set 0 0.5] to set pwm pin
> 0 to half way through the PWM range of that micro.
>
> The relative pwm may be a problem, so we could use the hz as the
> argument to control a servo for example. (where say 1000hz is stop)
>

you mean output, right? if you need to meassure an incomming pwm signal 
instead of an anlogue voltage, you just need to make a simple rc lowpass 
filter (one resistor and one capicator) to get an analogue voltage from a pwm 
signal.

again: setting or reading a pwm signal with a 50/50 cycle (0.5 in the 0..1 
range) is the same as reading an analogue voltage at 50% of Vmax for an 
analogue input ....

greets,

chris