[chbot] The X-plane multiplex problem

Paul Sharp paulsharp360 at gmail.com
Sat May 19 00:47:06 BST 2018


Hello Trevor,

Thank you for your interest.

Here is what I have just put together here
<https://docs.google.com/drawings/d/1f8SLsSIm2VDcym7C_tvF0J3xjTBrV1xGKGb4beIdqfM/edit?usp=sharing>.
I am sorry it doesn't address your questions specifically as I am not sure
of how to answer at this stage.

Cheers
Paul



On Thu, 17 May 2018 at 22:29, Trevor Wignall <zl3adz at gmail.com> wrote:

> Hi Paul
> I saw some push button switches with built-in lights on your display.
> Presumably these will also need to be driven from the computer. Could you
> tell us the voltage and current of these lights and how many lights need to
> be driven in total? Also are there any 7-segment displays or similar? I ask
> because in some ways having a lot of outputs is harder to achieve than a
> lot of inputs.
> Cheers
> Trevor
>
> On Thu, May 17, 2018 at 11:32 AM, Paul Sharp <paulsharp360 at gmail.com>
> wrote:
>
>> Dear All,
>>
>> Thank you for showing an interest in my project. It is very much
>> appreciated.  I am trying to get up to speed with electronics [beyond
>> beginner] as quick as my time allows (I am reading your comment,
>> researching your comment, reading my recently purchased electronics book
>> etc, then reading your comments again).
>>
>> For those of you who are interested in the project; here is  my google
>> plus page here
>> <https://plus.google.com/u/1/collection/Mra5TE?pageId=none>
>>
>> Thanks again for all the support.
>>
>> Cheers
>> Paul.
>>
>> On Wed, 16 May 2018 at 19:31, Mark Atherton <markaren1 at xtra.co.nz> wrote:
>>
>>> OK, before you pile in, he is using I2C on a VGA port. Very cool idea.
>>>
>>> -mark
>>>
>>> On 16/05/2018 7:27 PM, Mark Atherton wrote:
>>>
>>> Synco,
>>>
>>> Still not sure how X-plane connects to the I2C devices - maybe a USB to
>>> I2C bridge, or are you bringing the SMB bus directly off of the motherboard
>>> ?
>>>
>>> -Mark
>>>
>>> -----------------
>>>
>>> Couple of our messages have been corrupted, here is Synco's earlier
>>> reply to me
>>>
>>> -----------------
>>>
>>> Wed May 16 00:33:27 2018
>>>
>>> Hi Mark+,
>>> I've written a few plug-ins for X-Plane, rather than use the UDP
>>> protocol, yet by next meeting that'll most likely have changed and will be
>>> happy to share. If each panel was to be stand-alone, from all the different
>>> I2C port expanders out there, it's likely you would have spare I/O that
>>> would avoid multiplexing / scanning tricks. Also, if you are running Linux,
>>> and don't want to use a Raspberry Pi, another option is to use the I2C
>>> adapter on your monitor connector. I've done this in the past, (and will
>>> again), yet be careful to ensure voltage levels and device addresses don't
>>> conflict !
>>>
>>> For example here is what it looks like on my pc:
>>> $ sudo apt install i2c-tools
>>> $ i2cdetect -l
>>> i2c-3 unknown    NVIDIA i2c adapter 7 at 1:00.0  N/A
>>> i2c-1 unknown    NVIDIA i2c adapter 4 at 1:00.0  N/A
>>> i2c-4 unknown    NVIDIA i2c adapter 8 at 1:00.0  N/A
>>> i2c-2 unknown    NVIDIA i2c adapter 6 at 1:00.0  N/A
>>> i2c-0 unknown    NVIDIA i2c adapter 2 at 1:00.0  N/A
>>>
>>> $ sudo i2cdetect -y 0
>>>      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
>>> 00:          -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 70: -- -- -- -- -- -- -- --
>>>
>>> $ sudo i2cdetect -y 4
>>>      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
>>> 00:          -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 30: -- -- -- -- -- -- -- 37 -- -- 3a -- -- -- -- --
>>> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 50: 50 51 52 53 54 55 56 57 -- -- -- -- -- -- -- --
>>> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>> 70: -- -- -- -- -- -- -- --
>>>
>>> And if you run out of addresses you can always add a i2c-i2c bridge:
>>> https://www.aliexpress.com/item/TCA9543A-Low-Voltage-2-Channel-I2C-Bus-Switch-Interrupt-Logic-And-Reset-Module/32763291440.html
>>>
>>> /s
>>>
>>> On 15 May 2018 at 22:01, Mark Atherton <markaren1 at xtra.co.nz>
>>> <markaren1 at xtra.co.nz> wrote:
>>>
>>> > Hey Synco,
>>> >
>>> > Any chance of a quick tutorial how X-Plane processes incoming UDP
>>> packets, and assigns associated bytes/bit-positions to each function.
>>> >
>>> > Getting some kind of spec. from Paul (or help write one) would be very
>>> useful to determine cable loom lengths, number of inputs, types etc. For
>>> each control: Push Button, On/Off, Rotary (number of positions) ,or
>>> Potentiometer (and resolution), and max scan time.
>>> >
>>> > He may have been using a 4 position switch with 4 wires, when it may
>>> actually be an encoded 2-bit problem. Not sure if full size, low cost
>>> rotary binary outputs switches are readily available - hex coded switches
>>> are obviously too small...  There was mention of an R-2R ladder on the
>>> switch and an ADC - this seems a bit over the top (?). How about using a 1
>>> of 4 rotary switch, and a small diode matrix (4 diodes + 4 pull down
>>> resistors) to encode to binary - there are obviously larger bit-savings
>>> with 8 and 10 positions switches.
>>> >
>>> > Not personally a fan of carrying I2C any great distance due to noise
>>> immunity issues (or lack thereof), but screened twin cable (and associated
>>> unwanted capacitance) with low clock rate (10kHz ?) and careful grounding
>>> may be OK though.
>>> >
>>> > R-PI seems over the top to convert bits into UDP, but I guess they are
>>> readily available, well supported, and low cost, so why the hell not...
>>>
>>>
>>>
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>>
>>
>>
>> --
>> Paul
>> 0292 360 360
>>
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>
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-- 
Paul
0292 360 360
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