Jan Olof's Content

#9092 LCDKeypad 16x2 HD44780 Shield

Posted by Jan Olof on 07 February 2011 - 12:40 AM in Project Showcase

Hi The level converter is not supposed to scale a signal. It is just converting the high logic level to another voltage. Sparkfun says this: "Does not work with an analog signal." /Jan Olof

#9020 Pull Up/Down Resistors, and when to use them?

Posted by Jan Olof on 04 February 2011 - 11:47 PM in General Discussion

Hi Just to be clear, you only need a pull down resistor to inhibit the activating of the relay at reset when the pin is set as a input with a pullup resistor. Fred in his relay drive circuit have found that a 2,2 K Ohm resistor was a good value. 2.2 K will only draw 1.5 mA from the available 8 or 16 mA when the output is high. /Jan Olof

#8980 Connecting a beam load sensor to netduino

Posted by Jan Olof on 04 February 2011 - 09:03 AM in Netduino 2 (and Netduino 1)

Hi Aref is the reference voltage normally connected to 3.3V. On the A version of the boards you had to have an external jumper, on the B version boards it is default internally jumpered. /Jan Olof

#8947 SD Card Issues.

Posted by Jan Olof on 03 February 2011 - 08:37 PM in Netduino 2 (and Netduino 1)

alanb Please tell us if your 4GB card works, normally they don´t (mine Sandisk 4 GB did not work). If it should work, give us some more details of model and so on. /Jan Olof

#8849 SPI Sends Msb or Lsb

Posted by Jan Olof on 01 February 2011 - 11:10 PM in Netduino 2 (and Netduino 1)

No I have not tried out SPI yet, but I have an BMA180 that I want to use so I am following SPI discussions on the forum. I am trying to understand what your resistor will do. The only thing that come to mind is that it will delay the rising edge of the CS signal as the pullup is a rather high value resistor. You could test with an small capacitor to gnd instead of the resistor perhaps 1 or 4.7 nF. You could perhaps use an other pin and manipulate the CS signal yourself, all this just to verify it is an timing issue as I think. /Jan Olof

#8844 SPI Sends Msb or Lsb

Posted by Jan Olof on 01 February 2011 - 09:39 PM in Netduino 2 (and Netduino 1)

Hi Just to make sure, is the resistor in series with the chipselect signal? Also what value is it ? /Jan Olof

#8557 Analog Read

Posted by Jan Olof on 27 January 2011 - 02:50 PM in Netduino 2 (and Netduino 1)

Well I'm stumped. I don't think the netduino can measure current directly. You might need something like this that outputs varying voltage:

http://www.sparkfun.com/products/8883

Thats overkill!

You only need a resistor. Calculated by Ohms law.
You need a voltage drop of 3.3 V at 20 mA, and then you just measure the volage over the resistor with the analog input of the Netduino.

165 Ohm at 20 mA gives a drop of 3,3V (max for the Neduino analog input) (U=R*I)

I would select the one closest below 165 Ohm I can find, with 1% accuracy I would take 162 Ohm.

/Jan Olof

#8103 1-WIRE

Posted by Jan Olof on 22 January 2011 - 03:54 PM in Netduino Plus 2 (and Netduino Plus 1)

But it only allows for 1 sensor on each wire, so you have to have separate wiring for each sensor. Not good, when the sensors are a bit away. So please speed up the native support! /Jan Olof

#8098 Add Reference .NET tab empty

Posted by Jan Olof on 22 January 2011 - 09:35 AM in Visual Studio

Hi Shawn It is not only you. I just found out that if the focus is on the project Solution Window, Add Reference from the Project window have the .NET tab populated, if focus is an another window the .NET tab is empty. This explains why I had problem adding a reference a while ago (in anothere thread), I had to browse to add it, later I found it in the add reference dialog, I then blamed it on me being blind. /Jan Olof

#7667 NetDuino Quadrocopter

Posted by Jan Olof on 14 January 2011 - 05:51 PM in Netduino 2 (and Netduino 1)

Ok Brandon, You are not using the HK401B as a unit, just as a donator of parts (the gyro). Interesting. /Jan Olof

#7642 NetDuino Quadrocopter

Posted by Jan Olof on 14 January 2011 - 08:51 AM in Netduino 2 (and Netduino 1)

Hi I took a look at the gyros you proposed HK401B, I am nu RC or gyro expert but to me they did not look promising to interface with the Netduino. What I could see is that they was black boxes that you put in between your RC receiver and your servo, with no other data output you can use. Also what I understood so are they specialized to keep your heading and interfaced with rudder. But I might be very wrong here. Anyway take a look at sparkfun and their sensors, and the Gyro and Accelerometer guide. /Jan Olof

#7501 Powering Netduino+ with 5V

Posted by Jan Olof on 12 January 2011 - 09:26 AM in Netduino Plus 2 (and Netduino Plus 1)

Miha, Take a close looka at the cellular datasheet, there might be charging circuit in it! It says optional, but if that means it is an option you can order, or if it is optional to use I don´t know. Next question is if the pins you need to connect to is available on the shield. It is the small things that makes life complicated

. /Jan Olof

#7486 Powering Netduino+ with 5V

Posted by Jan Olof on 12 January 2011 - 12:48 AM in Netduino Plus 2 (and Netduino Plus 1)

That was not a good idea, powering the Netduino through VIN! VIN is the input for the 5V regulator on the Netduino so that needs at least another 1,5V so 7,5 gives you some headroom, the schottky diode on the barrel input is specified at 1 A. Probably it would not have problem with 2A peak, but as it is a remote setup, play conservatve. I would break out the power to the GSM module and power that directly with 5V (and power the Netduino through the USB connector). /Jan Olof

#7481 Powering Netduino+ with 5V

Posted by Jan Olof on 11 January 2011 - 11:55 PM in Netduino Plus 2 (and Netduino Plus 1)

The subject have drifted, this is about powering from 12V. From the datasheet of the regulator, at a ambient temperature of 25 C and a voltage drop of 7V it can supply 400 mA with L=25 mm copper (but I am not sure of the board layout). So I am sure it can handle the Netduino at 12V, but I am sceptic about drawing 800 mA at 12V input (depending on the board layout). Max junction temp is 150 C, at 25 C ambient then it can rise another 125 C, that means that at 5,6W dissapation the therman resistance must be below 125/5,6= 22,3 C/W and that is way outside the diagram shown for the DPAK. /Jan Olof

#7479 Powering Netduino+ with 5V

Posted by Jan Olof on 11 January 2011 - 10:54 PM in Netduino Plus 2 (and Netduino Plus 1)

Looking at the schematics and using some google, it looks as though it is 800mA.

The question is how good the regulator is cooled, if you supply with 12V you have to drop 7V
with 0,8A that makes 5,6 Watts to dissipate as heat (7,5 V supply you only have to drop 2,5V that makes only 2W as heat).

Chris:

Would a good solution be to supply +5V (a little more than 2A) on the VIN header, that would then power both Netduino+ and cellular shield one like this
Posted Image

/Jan Olof

#7473 Powering Netduino+ with 5V

Posted by Jan Olof on 11 January 2011 - 10:30 PM in Netduino Plus 2 (and Netduino Plus 1)

The cellular seems to take its power from the VIN and it is then regulated down to 3,8 V, on the netduino+ that seems only connected to the barrel connector. The 2000 mA is peak current, average is around 350 mA when transmitting. I would look for a wall brick that gives 3A at 7,5 V, Hmm, I looked did not find any, 5V 3A is common. You can perhaps break out the connection so you don´t take the power to the cellular from the netduino, and power the netduino via the USB connector. I would be careful supplying 12V, it might be on the limit for Netduino, and the cellular shield is dimensioned for 5V, the regulator there might go up in smoke with 12V (the datasheets are really very sparese with information). Those 2A peak makes it complicated, it is really built for a battery. Anybody with a better idea ? /Jan Olof

#7469 Powering Netduino+ with 5V

Posted by Jan Olof on 11 January 2011 - 09:28 PM in Netduino Plus 2 (and Netduino Plus 1)

Miha, You can power it with +5V through the USB connector, or with 7,5V to 9V (perhaps even 12V but that could be maginal on the regulator) through the barrel connector. The pin marked +5V is on the output of the regulator and I am not sure if that would be happy if you connect 5V here. I not sure what would happen on the USB if you connect a computer at the same time (I would not do it). I have the feeling that 5V 500 mA is to little to power for your cellular shield, you must check the datasheet or tell us which you will use. AD0 to AD3 can drive 16 mA the rest 8 mA but all outputs together max 200 mA. There is a note that 5V can make problems if you use the built in pullup (I don´t see exactly what the problem is). Chris: It would be nice if there was a specification for the card regarding I/O voltages and current and also power, now you have to dig into 687 pages CPU datasheet. /Jan Olof

#7422 Full-featured driver / test code for the Maxim DS1307 real-time clock

Posted by Jan Olof on 10 January 2011 - 06:55 PM in Project Showcase

Fabien, I have downloaded the zip file (and some of your other zip files), both winrar, 7h and the builtin in win 7 says that the files are damaged (downloaded both with IE8 and Chrome)

. Can you please check your website. /Jan Olof

#7419 Remote heating regulation

Posted by Jan Olof on 10 January 2011 - 05:46 PM in Netduino 2 (and Netduino 1)

Miha Which country are you in? I checked shipping to Sweden and that was 6$

/Jan Olof

#7405 Remote heating regulation

Posted by Jan Olof on 10 January 2011 - 09:14 AM in Netduino 2 (and Netduino 1)

Miha, Member CW2 is working on OneWire drivers for the Netduino. At the moment that needs special firmware, but it will bee integrated into the official release when ready. There is a prerelease in the forum somewhere (you have to search), if I remember correctly there is 2 versions the original and a updated. This firmware may not contain all the other updates that is in the Alfa releases you can find in the forum. /Jan Olof

#7363 Reading temperature from DS18B20 using OneWire

Posted by Jan Olof on 09 January 2011 - 09:49 PM in Netduino 2 (and Netduino 1)

Carsten, Forum member CW2 is developing a OneWire driver that does not need an external processor. It will probably be integrated in the official firmware release when finished. But there are a special release of the firmware available in the forums with OneWire support(can´t remember the thread). /Jan Olof

#7357 SD card

Posted by Jan Olof on 09 January 2011 - 08:11 PM in Netduino Plus 2 (and Netduino Plus 1)

THANKS

I was blind did not see it in .NET under add references!
I did know about be and le but completly forgot when I found the reference.

It works now so I can see the directorys on my SD card.

Thanks again!

/Jan Olof

#7351 SD card

Posted by Jan Olof on 09 January 2011 - 07:10 PM in Netduino Plus 2 (and Netduino Plus 1)

I found it in C:\Program Files (x86)\Microsoft .NET Micro Framework\v4.1\Assemblies\be /Jan Olof

#7349 SD card

Posted by Jan Olof on 09 January 2011 - 06:59 PM in Netduino Plus 2 (and Netduino Plus 1)

Hi I am trying to get my SD card to work. Have found some examples here, but they are not complete regarding namespace and references. I have seen a lot of references to System.IO.Directories... but Visual Studio don´t like that. Am I muissing a namespace ? I also saw this in another tread: " To use the SD card, add the System.IO.dll reference to your project." But I can´t find it to add. Probably something obvious but I can´t find out. /Jan Olof

#7344 Analog in put C# coding

Posted by Jan Olof on 09 January 2011 - 04:19 PM in General Discussion

Hi He uses Debug.Print that output should you see in the Output window when running the debugger. On my screen this window pops up in the lowe left corner, think I have standard configuration but not sure. And yes you can take some power from the 3.3V pin, but I am not sure how much is left after the Netduino have taken it´s share from the regulator. /Jan Olof