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Member Since 14 Jun 2011
Offline Last Active Jun 20 2017 09:27 AM

Topics I've Started

Gainspan WiFi module

25 February 2014 - 11:49 PM



I wonder if anyone can help, I am trying to get my gainspan WiFi module working with a netduino 1. I wonder if anyone has a library or can give me some help getting started in creating a library for it?


Many thanks



Netduino Go! 4.3 firmware

24 November 2013 - 02:50 PM



Is there any news on the Netduino Go! 4.3 firmware?


Many thanks,



Call for Secret Labs to Kick Start Go! Bus

02 September 2013 - 10:46 PM



I have been a happy user of Secret Labs products for many years, I have enjoyed the fantastic, friendly and helpful community and Secret Labs energy and commitment to improve their products.


Now I feel it is the communities chance to help Secret Labs...


I would like to propose that Secret Labs start a Kick Starter campaign to help fund the development of the Go! Bus protocol which is holding back many avid netduino users and the exciting new products Secret Labs have on backlog. The community have all been waiting patiently for ethernet, SD and the Gadgeteer hub for sometime and it seems focus has shifted and the forums have gone a little quiet.


I would like to know the viability to allow the community to "give a little to get a little", by funding Secret Labs so they can employ some additional resources to either work on the Go! Bus protocol, or work on the AGENT smart watch, freeing up other resource to work on Go! Bus.


I would love to start getting some use out of my N Go! and would love to see the netduino forums that bustling hive of community interest they were previously.


What are your thoughts on this?


Many thanks,



Help bypass switch with reverse current protection

26 August 2013 - 11:48 PM



I am trying to find a way to manually override the control of some relays.


The netduino uses mux to control 24v which switches the coil voltage of some relays. I want to manually control the relays in case something goes wrong on my control board or with my software.


The manual switches will carry 24v from the same supply that switches the relays on my control boards. Things that I am unsure about include, if the switch is closed supplying 24v to the the relay coil, but the control board is not is closed, how can I ensure current from the switch doesn't travel backward in to the control board mux circuit?


I guess this would be an easy answer with something like diode right? Any help on which one and where would be much appreciated?


Finally, what would happen in the switch was close supplying 24v and the control board was supplying 24v to the relay? Would this be fine as it is the same source or could this create some form of over voltage/over current?


Could this be resolved with a transistor and if so how would I wire it in.


Basically the ciruit has a common ground and the 24v is common to both the ULN2802 which will be used to switch the relay coil and to the switch which will directly supply the same 24v?


There is one final consideration, the relays have a 2.5v voltage drop and a 30ma current drop. How would I handle this in terms of resistors and the 2 possible sources of current (ULN2803 or Switch)?


I would also like a status LED to show which relays are on again 2.5v voltage drop, 30ma current drop.


Many thanks,



High power multiplexing help

26 August 2013 - 03:59 PM



I am just in the process of rewiring my house using a radial system or in fact 2 seperate radial systems (one for the basement/ground floor and one for the first floor/loft). By radial system I mean each socket and light goes back to the distribution board.


The idea is that I can control each socket or light separately and so each of these will terminate on its own solid state 25 amp relay that will be din rail mounted in the distribution board. Each light switch will run on a low power system using cat5 cabling and so all the switching will be done using solid state relays. This not only allows me to manually control the lights using manual switches, a 24v din mounted power supply and CAT5 cable to the relays. But it also allows me to centralised control that I can interface with via the netduino. The reason for this is that you must ensure that there is a switchable light per room and it acts as a backup in case I have a software or electronics issues, most importantly this also avoids the Mrs getting annoyed if she can't switch the light on etc. ;)


What I am trying to do is create some din rail mounted modules that will provide the switching control for the relays. Each module will use CAT5 connections to connect it back to a central module that will house the netduino and will split the SPI which will be used to multiplex the control logic and distribute the switching voltage from the 24v 3.2A 85W din mounted power supply.


Each module will switch 8x 25amp relays using 24v, will have 8 LEDs to indicate what is on, will contain a 74HC595 shift register, a 74HC245N CMOS and a ULN2803 transitor array, plus some resistors or resitor array.


The relays have approximately a 2.5v 30ma voltage and current drop respectively.


The 4 twisted pairs in the CAT5 will carry the 3 connections for the SPI, 1 connection to return QH from the 595s so they can be daisy chained, common Gnd, 3.3v and 24v.


What I need a little help with is as follows:

  • Am I missing any connections on the 74HC245Ns, there is a direction pin (pin 1) and a QE pin (pin 19). I am not sure what to do with these?
  • Can you see any errors in the circuit or see any problems that it might face, and can you offer any solutions if so?
  • As I will have a fair few of these boards and each will have 8 small 3mm leds 30ma 2.5v, would I be better moving the leds to the 24v side of the circuit and if so what will I have to change? Would I need any extra resistors, diodes, caps etc?
  • The resistors I haven't even calculated and this is something I am terrible at, if I leave the LEDs where they are now what resistors would I need? I was thinking of using a resisor array from my inspiration for the circuit (see below). However linked to the previous question what if I moved the LEDs up to the 24v circuit so they aren't running off the netduinos power? Posted Image
  • Would the circuit benefit from any caps to level things out and if so what size and where?
  • Final question do I need any additional protection diodes for the netduino or chips?

Here is a fritzing (see Din Mount Relay_bb.jpg) of what I was thinking for the Din Modules and there is also the netduino shield which distributes the 24v and SPI (see Din Shield_bb), any help moving the LEDs to the 24v side would be much appreciated!


As a key:

Red = 24v

Black = 3.3v (from netduino)

Green = Common Gnd

Orange = Returned QH

White = MOSI

Purple = SCLK

Yellow = SS



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