PPM & PWM Tester/Analyser
Posted: 27 Feb 2018, 01:05
Unfortunately the original project is now lost and I never kept a local copy - I didnt even have the drawing Ron posted - its soul destroying to realise how much time and effort has been lost from the old forum.
I have found a couple of photos of the vero layout but I've not been able to recover anything from Wayback or from my own backups.
So here is an attempt to retrospectively describe the Arduino PPM and PWM tester. Firstly, what is it for?
In a nutshell, it displays all the information contained within a PPM stream.
its ideal for testing new encoders before they're dispatched, ensuring that they generate PPM and that all the channels operate as expected. Its great for checking mixes, measuring servo outputs, setting up channel switches, etc...
As well as displaying channel values from a PPM stream, it also shows the pulse duration, pulse polarity, channel count, frame rate and sync pause length. Optionally it also drives 6 servos for test purposes.
It can sense if the input is a single servo signal, say from a receiver channel or a servo tester - and will automagically switch from PPM to PWM mode, displaying the servo pulse width.
I find it very hard to photograph back-lit displays, so I have to turn the white-balance right down,
hence the dark photo. Honestly, its clear as a bell in practise!
Here it shows a 20ms frame carrying 8 channels, using negative-going pulses of 300uS duration. The first 6 channel values are shown, 1500uS being 'neutral' of course. All values are shown in microseconds:
There is very little to it, just a slab of vero, a 4-line by 20-character LCD display from ebay, a Nano and a few headers. I haven't done a detailed vero layout but its very easy to recreate from this drawing, I've aligned as many connections as poss but there are some cuts and bridges to make. The hardest part is the servo block which is 'against the grain' as you can see in the vero photos. Track cuts have to be made between the servo block holes, or you could use a small vero strip mounted at 90 degrees to the mainboard, carrying the pos & neg to the servo block:
Checking the video I noticed a brainfart, I said 'sync pulse' when of course I meant to say 'sync pause'.
Also I forgot to mention that it measures PWM servo pulses too, ie from a receiver channel output:
Here's the diagram which is also a suggested layout: NOTE the weird orientation of the contrast preset pot - see 'top' photo.
Sketch is here:
It uses the Hasi method to read the PPM with a resolution of 0.5uS.
and here's Ron's S/C transmitter connected to the PPM tester...
...and an explanatory diagram showing how the numbers relate to the PPM stream:
Thats it chaps, works well, accurate, does the job
Cheers
Phil
I have found a couple of photos of the vero layout but I've not been able to recover anything from Wayback or from my own backups.
So here is an attempt to retrospectively describe the Arduino PPM and PWM tester. Firstly, what is it for?
In a nutshell, it displays all the information contained within a PPM stream.
its ideal for testing new encoders before they're dispatched, ensuring that they generate PPM and that all the channels operate as expected. Its great for checking mixes, measuring servo outputs, setting up channel switches, etc...
As well as displaying channel values from a PPM stream, it also shows the pulse duration, pulse polarity, channel count, frame rate and sync pause length. Optionally it also drives 6 servos for test purposes.
It can sense if the input is a single servo signal, say from a receiver channel or a servo tester - and will automagically switch from PPM to PWM mode, displaying the servo pulse width.
I find it very hard to photograph back-lit displays, so I have to turn the white-balance right down,
hence the dark photo. Honestly, its clear as a bell in practise!
Here it shows a 20ms frame carrying 8 channels, using negative-going pulses of 300uS duration. The first 6 channel values are shown, 1500uS being 'neutral' of course. All values are shown in microseconds:
There is very little to it, just a slab of vero, a 4-line by 20-character LCD display from ebay, a Nano and a few headers. I haven't done a detailed vero layout but its very easy to recreate from this drawing, I've aligned as many connections as poss but there are some cuts and bridges to make. The hardest part is the servo block which is 'against the grain' as you can see in the vero photos. Track cuts have to be made between the servo block holes, or you could use a small vero strip mounted at 90 degrees to the mainboard, carrying the pos & neg to the servo block:
Checking the video I noticed a brainfart, I said 'sync pulse' when of course I meant to say 'sync pause'.
Also I forgot to mention that it measures PWM servo pulses too, ie from a receiver channel output:
Here's the diagram which is also a suggested layout: NOTE the weird orientation of the contrast preset pot - see 'top' photo.
Sketch is here:
It uses the Hasi method to read the PPM with a resolution of 0.5uS.
and here's Ron's S/C transmitter connected to the PPM tester...
...and an explanatory diagram showing how the numbers relate to the PPM stream:
Thats it chaps, works well, accurate, does the job
Cheers
Phil