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There have been 35 items by Paul Newton (Search limited from 28-April 23)

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#59926 Powering EasyDriver and Netduino

Posted by Paul Newton on 28 August 2014 - 06:16 PM in Netduino Plus 2 (and Netduino Plus 1)

Hi Andre,

If the EasyDriver you are referring to is the SparkFun EasyDriver, then the A3967 IC on the board has built in protection diodes so that its internal transistors are not damaged by back emf.

You are right to worry about the motors affecting the Netduino. I was using a similar circuit with a 9V battery supply (6 x AA 1.5V) for my buggy and had to give up powering both from the same supply because the Netduino kept re-booting when the motors turned.

I was never aware of any damage to the Netduino - I think it was just brown outs, or maybe noise that was enough to trigger a reset..

If you are worried that the driver board will feed current back to the 12V supply, then add a rectifier diode in the positive line between the battery and the driver so it can only take current - that should protect the Netduino from high voltages.

(Note that the EasyDriver circuit does not have any protection for its own logic supply, so I don't think they are expecting any problems like this. However they do have a 30V tolerant input.)

You might also add a similar diode to the Netduino supply input and add a big capacitor after the diode so that short brown outs are less likely to reset the Netduino.

Let us know how you get on.

Have Fun - Paul

#59707 GPIO Start Low

Posted by Paul Newton on 14 August 2014 - 05:45 AM in Netduino Plus 2 (and Netduino Plus 1)

Hi,

I solved this problem for my robot buggy by using opto-isolators.

I was using the Netduino Plus v1 whose pins are pulled high with weak pullups at reset.

These pullups were enough to activate the H-bridge circuit for my motors, but not enough to activate an opto-isolator's LED.

A single isolator was a small package so not a problem to fit into a small space, and they also make multiple devices.

The one I used was and still is �1.39 GBP in the UK from Maplin.

Its all written up on this WIki page: Driving high current / voltage loads.

Have fun - Paul

#58637 Problem driving DC Motor with HBridge

Posted by Paul Newton on 08 June 2014 - 01:40 PM in Netduino Plus 2 (and Netduino Plus 1)

We have all been there Ken!

Welcome to the Forums.

Paul

#58481 Netduino Plus Ethernet - Interrupt-driven libraries?

Posted by Paul Newton on 30 May 2014 - 06:17 AM in Netduino Plus 2 (and Netduino Plus 1)

I've almost completed the motor mount for the stepper motor for the turntable (needed two unusual-sized drill bits which I picked up this morning). After it's mounted, I can get serious about the programming portion.

I have been playing with some tiny RC servos to motorise my points (turn outs).

The board I have fits into the skirt under our living room table. The board has to be flush underneath - e.g. no solenoids or wires can stick out because people sitting at the table will hurt their legs!

I have located some very thin servos and found that I can use a router / multitool to cut a blind hole in the board under the points that the servo sits in. I added some folded aluminium to allow me to adjust the position of the servo and nail it in place when the point works well.

I found that using servos was actually cheaper than any thing else I could buy to achieve the same job. Now I need to actully fit to the board and work out how to route all the wires!

Paul

#58480 Browser problem: Firefox spell checker not working in edit box

Posted by Paul Newton on 30 May 2014 - 06:08 AM in General Discussion

Paul, those two rightclick context menus are for two different HTML elements. The one with the spill chocker is from the <textarea> where you type text, the other one seems to be for an <iframe>. My guess is that it isn't the amount of text, but rather where in the textbox you rightclick that matters.

Try typing just a single word, and then rightclick on the word itself.

In your two examples you can try clicking the last menuitem, "Inspect Element", and you should see that you end up in two different part of the HTML source.

OK I give up.

I just spent a minute right clicking and found that it seems to go in runs of one menu or the other.

I just right clicked with no text at all this time.

At first it seemed like clicking near the flashing cursor gave the spell checker menu, but I found that once that menu is up, clicking further away gives the same menu.

Eventually it changed when I was half way across the edit box and then as I worked my way back towards the cursor, I kept getting the non-spell checker menu.

Once I had started typing this, I could no-longer get the wrong menu, so I'm not sure about the object inspection.

I have decided that I don't care why its doing it. If you keep clicking in different places, you will eventually get the required menu and then will be able to enable the spell checker. The more text the easier it gets.

I have already spotted several mistakes as I am typing this - so I'm happy (if still confused).

Thanks everyone - Paul

#58460 Browser problem: Firefox spell checker not working in edit box

Posted by Paul Newton on 28 May 2014 - 07:56 PM in General Discussion

What _do_ you get when you right click in the edit box? Websites can replace the right click menu, but working around that is pretty simple with add-ons, but before you go down that road you'd want to confirm that's whats going on

Thanks Wendo, you got me clicking and I managed to solve the problem.

What I found is that the right click menu changes with the amount of text in the edit box.

If there is only one line, then the menu does not have the option for the spell checker.
If there is another line, then the "proper" menu is there.

I have now managed to enable the spill chequer, unfortunately the using the wrong word checker is not enabled.

The screen shots of the two menus are below. As you can see, in both edit boxes the gggg is underlined in red now that have enabled the checker, but the menu options to control are missing in one.

Paul

Attached Thumbnails

#58441 Watchdog Reset Problem

Posted by Paul Newton on 27 May 2014 - 08:17 PM in Netduino Plus 2 (and Netduino Plus 1)

Happy to help.

Would be great to see a picture.

Even better if you add a wiki page!

#58401 Browser problem: Firefox spell checker not working in edit box

Posted by Paul Newton on 26 May 2014 - 11:54 AM in General Discussion

Thanks guys,

I don't want to use Chrome. I have a few suspicions about what it does in the background.

I have not looked at the HTML, was just hoping that if someone else is using Firefox OK, they could let me know what I am doing wrong.

Perhaps Secret Labs have tested the site with a few brewsors and have a list of wirkong ones.... Nudge.

Paul

#58398 Browser problem: Firefox spell checker not working in edit box

Posted by Paul Newton on 26 May 2014 - 07:28 AM in General Discussion

Hi Everybody,

I am using firefox (v29.0.1), I have a British English dictionary installed, when I am on a non-Netduino site with an edit box, I can right click in the text box and verify that I have the spell chekcer enabled, and if I make a mistake, the text is underlined (I make lits of spolling mastakes).

On the Netduino Forums, right click does not give me the firefox menu, and the above mistakes are not underlined in red as they would be on another site's text box.

Is there any way to get the spill chocker working??

Does the same thing happen with Internet Explorer?

Paul

#58397 Watchdog Reset Problem

Posted by Paul Newton on 26 May 2014 - 07:09 AM in Netduino Plus 2 (and Netduino Plus 1)

Hi Guido,

I have just looked at the Netduino plus V2 schematics.

The external reset appears to be an input only, I can see this because the /EXTERNAL_RESET signal is connected to the base of an NPN transistor. It can't act as an output, so it should not be affecting the reset chip.

Have you tried powering the reset chip from an external supply, whilst connected to the Netduino?

I am wondering whether the Netduino is affecting the 3.3V supply as it re-boots, causing the reset chip to give up.

On the schematic, the 3.3V on the header "+3V3_HEADER" appears to be connected to the 3.3V regulator via a transistor - it is controlled by a signal called "CTRL_OF_PWR_HEADERS" which is an output of the ARM chip.

The more I look, the more I think the power is being cut off when the ARM reboots. Also it looks quite hard to locate a place where you can access the unswitched 3.3V.

One place that looks like it might work, is the mini-jtag connector. This has +3.3V, Gnd, and /RESET pins. I guess that's perfect for a reset generator. If you were to modify the firmware, you might even be able to use one of the JTAG GPIO pins to send a don't reset signal to the reset chip using one of the other pads on the mini-jtag connector.

Hope this helps solve the problem - Paul