PoKeys USB Interface

[Wendy]

Hey Philip,

Funny you ask because I'm writing a small program that can drive a servo directly connected to a PoKeys USB card. It is not yet completely finished but it works already. When changing the flap lever the servo moves slowly to the choosen flap setting. It will work with FSUIPC.

As soon as it is ready I'll post a link to the program.

Regards, Wendy

[flatdog]

Wendy,

That is great news - thank you. Is there a way forward for things like EGT, Fuel Temp and brake pressure? I can see the outputs in the ProSim737 interface but am not entirely sure how to make best use of them.

Regards,

Philip

[Wendy]

I don't know, I'm not that far. Maybe it is better to ask this question on the ProSim forum.

Regards, Wendy

[tlhflfsx]

Wendy,

I was able to get a poKeys55E (ethernet version) for testing and have created an updated lua script that shows how to connect to both the USB version and the ethernet version. The script also contains more examples of how to interface to the poKeys device that others may find useful.

Please remove the original file on your web site and replace it with this file.

Terry

[Wendy]

Thanks Terry for the updated script. You seem to have a very good understanding of LUA-scripting, very nice.

Regards, Wendy

[flatdog]

Wendy,

I am sorry to ask such a basic question but could you confirm the way to connect a servo to a POKeys55 card. I have a HiTec servo with red (+), black (-) and yellow (signal) wires. I am also a little unsure as how the pins should be configured in the POKeys software.

Many thanks,

Philip

[Wendy]

Hey Philip,

The black and red wire are the power, so + 5Volt. The black one goes to the ground on the PoKeys card. The red one I connect to a separate power supply of 5 Volt (because the Pokeys have only 3,3 Volt and that is not enough for the servo). Ground of servo and Pokeys have to be connected. Make sure you make no mistake, otherwise the PoKeys card goes to heaven. The yellow goes to a PWM output port on the PoKeys.

You can check the working of the servo via the included software "Peripherals - PWM outputs".

If you want to drive the servo via external programming (see also the PoKeys examples), here is which values to use.
RC servos require a pulse with the width between 1 and 2 ms, with 1.5 ms being the center position. Furthermore, these pulses must be sent at approximately 50 Hz (20ms period).
In order for this to work properly, use the following settings:
- PWM period: 20 ms * 12 000 cycles/ms = 240 000
- PWM duty: 1-2 ms * 12 000 cycles/ms = 12 000 (one end) to 24 000 (the other end)
The 'good' values for the PWM duty are therefore only between 12000 and 24000. Some servos may support signals that are out of the 1-2ms range. Adjust the duty cycle accordingly.

Hope this helps you.

Regards, Wendy

[flatdog]

Wendy,

Many thanks for your detailed reply. I had assumed that the '5v' port on the opposite side of the card from the '+3.3v' was a 5v supply but obviously not. Can you tell me what it is for?

Regards,

Philip

[Wendy]

Well it is indeed a 5 Volt connection, haven't noticed this before

You could use it if you're servo uses les power than the usb port can provide. For me I do not like to power them from the USB-bus.

Regards, Wendy

[flatdog]

Thank you. I hope you did not think I was trying to be 'clever', it was certainly not my intention. I am gradually getting to grips with these cards - I think they have huge potential. I have a slide potentiometer connected to the 5v port controlling a test throttle which seems to work well but I wasn't 100% sure what I was doing. I am keen to experiment but do not want to destroy the card so your advice is much appreciated. Out of interest what do you use for your 5v supply. I have been stripping a 350W PSU from an old PC but haven't quite finished it yet.

Regards,

Philip