Wireless connection to Velleman K8055/VM110

[pmlogg]

I've acquired a used Pulsar rotation system to provide the mechanical system but would like to modify it to allow computer control via Levesdome. 

I've read the interesting posts by others about power transfer to a motor on a rotating dome but instead I was minded to try to achieve it using the existing battery. 

From what I've read the Velleman board needs to be connected via its usb socket for communication as well as power.  A wireless usb hub looked like a possibility but those currently available (please correct me if I'm wrong) seem to be very limited on what usb components they can be used with (printers and storage devices mainly). 

Another alternative would seem to be to have a compact dedicated computer equipped with wifi to act as the wireless usb hub.  One of the Intel Compute Sticks, to connect via Windows Remote Desktop, seems like it might be an easier option for me than using a Raspberry Pi (but again correct me if I'm wrong) and compared with more capable mini-PCs be less power hungry.

I've read that the early Compute Sticks were slow and Wifi not great but the Atom x5-z8300 version has two physical usb ports rather than just one plus more on the AC adapter on the m3/m5 versions, and it uses less power.  My thoughts were that, if just using it for Levesdome and the connection to the main PC, it and the battery would be able to cope.  Attached is a block diagram of what I mean.  I would need to step down power from the battery's 12V DC to 5V.

Any comments on that would be very welcome as I my electronic knowledge is very limited.

[steppenwolf]

Is there any way that you could run a Cat 5 network cable to your dome from your home PC? This would remove one set of comms. challenges from the equation.

Although I no longer use it, I used to have a Lesvedome system for dome rotation and dome shutter control and it worked very well but I used an old Windows XP PC in the dome and controlled this remotely using TeamViewer down the network cable. I also used a second VM110 to control a whole set of observatory components and, in fact, I continue to use this part of the Lesvedome system even now as it saved me having to design and program a complete new control system for my ancillaries.

[pmlogg]

Steve

Thanks for your reply.  I have Cat 5 from the PC indoors to inside the dome, along with cabling to a remote keyboard, mouse and monitor so that I can control the mount and cameras either locally or from indoors.  The issue is that for observatory control the Velleman Card will need to be on the rotating part of the dome along with the rotation motor etc., all powered by the 12V battery.  I need to establish a wireless link to its usb input and the options seemed to me to be either a dome mounted mini PC with low power consumption, e.g. a Compute Stick or a wireless usb hub.  The 2nd alternative would remove the need for a 2nd PC but I've not been able to identify a currently available wireless hub that would work with a K8055/VM110. 

I don't know if the K8055/VM110 might alternatively be communicated with by an add-on Wifi card (but still powered by battery. Another,  more complex solution, might perhaps be to add wireless relays, allowing the Velleman card to be on the non-rotating part of the dome, directly connected to the PC by usb.  I know nothing about wireless relays but they seem to exist.

Thanks, Peter

[hughgilhespie]

Hi Peter,

My solution, which is based around the Lesvedome / VellemanVM110, is to have the main control box mounted on the static part of the observatory. I added an Arduino based controller to the Velleman system. The Velleman board responds to the Lesvedome ASCOM driver and rather than using the Velleman outputs to switch the  motor control relays on or off directly, the output signals are picked up by my homebrew Arduino board. This board then controls the motors. I actually use stepper motors but you could just as easily use the Arduino board to control relays to switch DC motors on/off. The big advantage of sending the motor control signals via an Arduino is that you can use fairly cheap wireless modules to send the signals to another battery powered Arduino / relay motor controller mounted on the rotating dome.

I realise this is a bit daunting if you are not comfortable with using Arduinos or similar but it does make for a fairly straightforward solution to automating the dome shutter. My system using stepper motors could be much simplified to become a relay driven system. In fact, thinking about it you could use the classic Lesvedome VM110 relay circuit for the dome rotation and all you would need to add for remote shutter control would be two ready made boards, Sparkfun Teensy 3.1 XBee adapters available from Cool Components in the UK, together with the Teensy 3.2 and XBee modules and probably a relay board. 

If this is of any interest please send me a PM and I will be happy to give you more details.

Regards, Hugh

 

[pmlogg]

Hugh

Many thanks for that.  I will think that through and either respond here or via a PM.

Thanks

Peter

[sloz1664]

On 09/04/2018 at 11:37, hughgilhespie said:

Hi Peter,

My solution, which is based around the Lesvedome / VellemanVM110, is to have the main control box mounted on the static part of the observatory. I added an Arduino based controller to the Velleman system. The Velleman board responds to the Lesvedome ASCOM driver and rather than using the Velleman outputs to switch the  motor control relays on or off directly, the output signals are picked up by my homebrew Arduino board. This board then controls the motors. I actually use stepper motors but you could just as easily use the Arduino board to control relays to switch DC motors on/off. The big advantage of sending the motor control signals via an Arduino is that you can use fairly cheap wireless modules to send the signals to another battery powered Arduino / relay motor controller mounted on the rotating dome.

I realise this is a bit daunting if you are not comfortable with using Arduinos or similar but it does make for a fairly straightforward solution to automating the dome shutter. My system using stepper motors could be much simplified to become a relay driven system. In fact, thinking about it you could use the classic Lesvedome VM110 relay circuit for the dome rotation and all you would need to add for remote shutter control would be two ready made boards, Sparkfun Teensy 3.1 XBee adapters available from Cool Components in the UK, together with the Teensy 3.2 and XBee modules and probably a relay board. 

If this is of any interest please send me a PM and I will be happy to give you more details.

Regards, Hugh

 

Hi Hugh,

I'm desperately seeking a solution to automate my shutter and although I have figured out how to drive the dome, mechanically & electrically (via 12v battery) I'm having difficulty finding a wireless solution for communication via the Velleman boards. If you could walk me through suitable solution, I would be eternally grateful.

Steve

[hughgilhespie]

Hi Steve,

Happy to help if I can. I used XBee radio modules in my design. They work very well but they are a tad expensive. There is another radio module, nRF24L01, that is much cheaper and is the one I would now recommend. If you look on http://embeddedcoolness.com/shop/ they are selling a breakout board called theRFX Nano 3.0 dev board w/ shield breakout, prototyping area, for use with an Arduino Nano and the nRF24L01. I have just bought 4 of these to have a play with. They  use the full WiFi capability of the nRF24L01 but you don't need that. All you have to do is use the nRF24L01 modules to send basic serial data between two Nanos - one fixed and one in the rotating roof. The fixed Nano will have pins connected to the Velleman board as follows:

DO5 Shutter Motor On/Off

DO6 Shutter Open/Close  (Motor Direction)

Analog Input 1 - Shutter Limit Switch 1

Analog Input 2 - Shutter Limit Switch 2

Based on the state of the 4 pins, the fixed Nano will send a serial message to the shutter Nano to start or stop the shutter motor or to change its direction. Obviously, the 5 volt, 20 mA or so output from a Nano pin won't drive a hefty motor so some form of relay board will also be required for the motor switching. I strongly recommend that you also use limit switches to detect when the shutter is fully open / closed. These limit switches will be connected to the motor relays and also to the shutter Nano so that they will switch off the power when the movement is complete  and also will send a serial message to the fixed Nano that will cause the fixed Nano to send a message to Lesvedome via the Velleman analog inputs.

To go any further can you describe how you are planning to control the shutter motor? When I know that I can try and flesh out my ideas.

Regards,

Hugh

 

[hughgilhespie]

Hi Steve,

A quick update. I should have asked how confident you are at soldering bits together. The ability to solder is pretty fundamental to messing about with Arduinos and the like. Funnily enough, the ability to write code is not so important - other people can help here but they can't solder the bits for you.

Anyway, for now I will assume that you are okay waving a soldering iron around. Today I will make a start on making up a couple of the Nano / nFR24 boards I received from the States. After that I can start thinking about the interface with the Velleman board and a suitable comms protocol for shutter operations. 

Regards,

Hugh

[sloz1664]

Hi Hugh, thanks for replying so promptly. Yes, I am adept at soldering and have built quite a few arduino projects around Mr R Brown's astro gems. Code I am not familiar with at all. I am controlling the shutter motor via the following wiring diagram:-

The motor would be driven a 12v battery mounted on the dome and I presume the wireless control would be via Digital pins 5 & 6.

Steve

[sloz1664]

Hi Hugh, forgot to add, the shutter travel would be controlled by lever actuated limit switches and the circuit would be self contained. I have built the circuit using a spare K8055 board and it works well.

Steve

[sloz1664]

Hugh, here's a better schematic for the shutter control:-

Steve

[hughgilhespie]

Hi Steve,

Thanks for the shutter motor schematics. Please can you email me the schematic directly as my tired, old eyes have trouble reading it on here. I assume that your Pulsar only has one shutter and you will not need the limit switches for the 'lower shutter'? I also think that your choice of lever-operated micro switches is a good one. I have had bad experiences with trying to use magnetic reed switches, they have too much hysteresis to allow accurate mechanical positioning. 

So, from what I can gather, you already have the relays and the lever operated micro switches. So, the shutter radio control module needs to have the following:

A 12 volt to 5 volt power supply.

nRF24 / Nano board to receive the incoming signals from the static board 

A way of boosting the Nano outputs to drive the K5 and K6 relay coils. This will be a ULN2803a chip which is the same driver as used on the K8055.

 

The static radio control module needs to have:

A 12 volt to 5 volt power supply.

nRF24 / Nano board to receive the incoming signals from the Velleman K8055 board, pins DO5 and DO6 and to send signals to the two K8055 Analog inputs.

There are some interesting optional extras for the static module. There are plenty of GPIO  pins unused on the Nano and one of these could be used for say monitoring a rain sensor that activates a relay when rain is detected to automatically close the shutter if it rains. I use a Hydreon RG11 that has a built in relay for this.  https://shop.weatherstations.co.uk/hydreon-rg-11-optical-rain-sensor-800-p.asp

 

When I've finished making the two nRF24/Nano boards I will do a strip board design for the shutter radio module.  The strip board will carry the nRF24/Nano board and the ULN2803 chip and the 12 volt to 5 volt regulator components. 

Regards,

Hugh

 

[sloz1664]

23 hours ago, hughgilhespie said:

Hi Steve,

Thanks for the shutter motor schematics. Please can you email me the schematic directly as my tired, old eyes have trouble reading it on here. I assume that your Pulsar only has one shutter and you will not need the limit switches for the 'lower shutter'? I also think that your choice of lever-operated micro switches is a good one. I have had bad experiences with trying to use magnetic reed switches, they have too much hysteresis to allow accurate mechanical positioning. 

So, from what I can gather, you already have the relays and the lever operated micro switches. So, the shutter radio control module needs to have the following:

A 12 volt to 5 volt power supply.

nRF24 / Nano board to receive the incoming signals from the static board 

A way of boosting the Nano outputs to drive the K5 and K6 relay coils. This will be a ULN2803a chip which is the same driver as used on the K8055.

 

The static radio control module needs to have:

A 12 volt to 5 volt power supply.

nRF24 / Nano board to receive the incoming signals from the Velleman K8055 board, pins DO5 and DO6 and to send signals to the two K8055 Analog inputs.

There are some interesting optional extras for the static module. There are plenty of GPIO  pins unused on the Nano and one of these could be used for say monitoring a rain sensor that activates a relay when rain is detected to automatically close the shutter if it rains. I use a Hydreon RG11 that has a built in relay for this.  https://shop.weatherstations.co.uk/hydreon-rg-11-optical-rain-sensor-800-p.asp

 

When I've finished making the two nRF24/Nano boards I will do a strip board design for the shutter radio module.  The strip board will carry the nRF24/Nano board and the ULN2803 chip and the 12 volt to 5 volt regulator components. 

Regards,

Hugh

 

Brilliant Hugh, pm'd you btw. and thanks for your input. I am in the process of building Robert Brown's MySQM meter  and have a cloudwatcher system, which I will integrate into the shutter circuit. I will be very interested in your finished strip board design for the shutter radio module.

Steve

[hughgilhespie]

Hi Steve,

A quick update.  After I got your reply where you mention building Robert Brown's MySQM meter it occurred to me that a radio link for shutter control in observatories using the Lesvedome system might be of interest to a few people. To this end I decided to tackle this in the same way as Robert's very useful projects and to prepare a project called 'Magic Wire'.

I have now actually build a pair of complete radio modules and I have tried to document the design and building process sufficiently to allow other people who may be interested to have a go themselves.

The stage I am now at is that the first draft project documentation is written and I now will start writing the code for the Arduino Nanos, followed by testing. I don't have a spare K8055 board or any relays so my testing will be limited to spoofing the inputs and checking that the outputs respond correctly.

I have included the draft documentation - excluding the code for now - and I would welcome your comments.

If we finally get this up and running, with you as the guinea pig for final testing, I would send the project to Pierre to see if he would like to include it on the Lesvedome web site.

Regards,

Hugh

LESVEDOME DOME CONTROL HARDWARE.docx

[sloz1664]

Hi Hugh,

I've just picked this up. I'm away at the moment, with limited signal, and will be back at the weekend. Certainly be the guinea pig

Steve

[hughgilhespie]

Hi Steve,

Glad you can do the testing. I am away myself until Monday so will start doing the software when I get back.

 

Regards, Hugh

 

[sloz1664]

Hi Hugh,

Just reviewed your comprehensive instructions on the "Magic Wire" Shutter Control and they are excellent. Although I haven't seen the circuit diagram, you have listed, in the Technobots section, ceramic capacitors, but no reference to their rating?

Just want to order the components, but I have a good stock at home. Although I have ordered the components from Embedded Coolness.

Steve

 

[hughgilhespie]

Hi Steve,

Thanks for your kind words.

The ceramic caps I used are 50 volt rated, 0.1 and 0.33 uF. The Embedded kits include the 0.1 caps. The L78S05 regulator specifies an 0.33uF and I thought it best to stick to the recommended values.

Regards, Hugh

 

[sloz1664]

Thanks Hugh, Components ordered.

Steve

[hughgilhespie]

Hi Steve,

IGNORE THIS!! JUST PLAIN WRONG. CORRECTED VERSION SHORTLY!!!

I have revised the strip board layout for the Static radio module. I hadn't allowed for the fact that most people using the Lesvedome system and following the schematics on the Lesvedome site will be using 12 volt relays and connecting the Velleman / K8055 CLAMP terminal to the 12 volt rail. This means that when the outputs from DO5 and DO6 are inactive, they will be around 12 volts which is much too high for the Nano pins that are connected to them.

I have added a simple voltage divider to each connection, so another 4 resistors are needed, 2 by 3.9 k and 2 by 2.0 k. This will reduce the 'off' voltage to about 4 volts which is fine. The 'on' voltage will still be around 0 volts.

My apologies if this causes you any problems!

In terms of general progress, I am getting on with the firmware for the boards. I should be in a position to start debugging / testing over the weekend.

Regards, Hugh

Static_Module_Rev0.1.pdf

Edited August 23, 2019 by hughgilhespie
I have erred grievously!

[hughgilhespie]

Hi Steve,

CORRECTED STRIP BOARD LAYOUT

I have revised the strip board layout for the Static radio module. I hadn't allowed for the fact that the digital outputs from the Velleman / K8055 boards require the use of pull-up resistors in order to generate a voltage swing when switching. The new layout uses an extra 2 off 4k7 pull-up resistors, tied to the +5 volt rail. When the Velleman / K8055 outputs are INACTIVE, the voltage seen at the Nano pins will be about +5 volts. When the outputs go ACTIVE, the voltage will drop to about 0.2 volts.

My apologies if this change causes you any problems!

In terms of general progress, I am getting on with the firmware for the boards. I should be in a position to start debugging / testing over the weekend.

Regards, Hugh

Drawing2_Rev0.1.vsd

[sloz1664]

Hi Hugh,

Thanks for the update and problems with the changes, I've plenty of 4.7k resistors. Just waiting for the delivery from the states.

Steve

[hughgilhespie]

Hi Steve,

Glad to know my daftness hasn't caused any problems. On that subject, I also sent you the drawing of the updated strip board layout as a Visio file rather than a PDF which I meant to send. Attached is the PDF version which should be much easier to read.

Regards, Hugh

Static_Module_Rev01.pdf

[sloz1664]

Hi Hugh,

No problem, I have Visio installed anyway so I could read the PCB image. thanks for the PDF version anyway. I also purchased a Velleman K8015 relay switch to set-up a Dead man's handle. I already have a UPS in the obsy.......but just in case

Steve

[Gina]

It's many years since I used one of those Velleman boards.  Nowadays I use the Raspberry Pi to which I add my own interfaces.