Tuesday, June 26, 2012

Netduino - Update Relay Control Board Mock-Up

I have finally managed to get my relay control board prototype working. What this allows me to do is control the relays with 12 volts and also to light a 12v LED to display which relays are on.

I am currently using a 74HC595 to provide the control logic to switch the transistors on and off. The next stage is to control the fans using PWM, I also need to add a DS18B20 that will connect in to my 1-wire bus. The temperature sensor will be used to control the speed of the fans, I may in fact used 2 temperature sensors to control the 2 fans independently for each of the heat sinks.

As I now have a Netduino GO I am working towards modularising my main aquarium control board. The first thing I want to modularise is this control board so it will work with the GO bus. I am hoping that the STM8 will provide enough IO to control the transistors and also PWM for the 2 fans. It would also be amazing if there was a spare serial port so I can create a 1-wire bus on the same board, but I have a fair bit of learning to do before I can get started with the STM8S103F2P6 chips I've got.

Here is a little video showing the shift registers switching the transistors on and off that control the LEDs.


  1. Hi McInnes,
    So you did go with the go configuration, how is it going?

    magpie here.

    1. Hi Magpie

      I haven't done much with the GO yet, I have bought one and the touch screen display, but I am being proactive with my controller first. I am intelligently trying to group functions at the moment to create a set of modules that will ultimately provide me with the functionality my original aquarium control board design offered.

      I also think that making modules is a much better approach for design work as you get a sense of achievement when you complete something completely as opposed to just a small part of a big project. Plus it makes bug tracking a lot easier (which is also a key reason I have changed my design completely).

      Have you looked at the STM8s yet? I really want to get some 1-wire functionality from the STMs but can't work out if it is possible. I need this for my temperature controls which seem to feature highly in this project, ranging from the relay enclosure, to my lighting enclosure and also the for the tanks themselves.

      My first plan is to get this relay control board finished to run on the standard netduino then work out what I need to do get it working with an STM8. Ideally the STM8 will give me 2 PWMs, 6 logic, and a 1-wire bus. This will allow me to pretty much make any of my modules then and follow a standard design throughout.

      How are you getting on with picking parts for your new attiny board? Are you going the 3 channel route still now you've moved channel 3 or have you had any more though on the attinyx25s?