I’ve made this board for some future projects with conductive ink, which I bought from Bare Conductive. The board has 3 buttons + a reset-button and 3 LEDS. It also has 6 pads that break out on each side (the bottom was supposed to be bare copper on the pads, but this way it’ll work as a cap-touch sensor if I want it to. It also has a battery-holder, programming pins and room for 2 4-pins external contacts. I think it can work ok as a general-purpose board for various projects when using a small battery.
Just a small post with a useful tip. If you want to make a capacitative touch sensor, you don’t need to use some fancy pre-made PCB board. You can actually use conductive tape, such as Aluminium tape as the sensor. Below is a picture of a test I did using a piece of paper, but it should also work with cardboard. As the microcontroller, use a touch-enabled MSP430 such as MSP430G2452 or MSP430G2553. You’ll get this by ordering a MSP430 Launchpad, which has two sample chips and a programming board for loading the firmware onto the chip.
Here are the instructions:
Find an enclosure for your product. For example the cardboardbox your MSP430 Launchpad came in.
Tape a bit of aluminium tape on top of your box. If you want more buttons, place several pieces of tape. Fasten a wire to each of these and attach these to Pins 2.5 (and other pins if you want to) on the MSP430.
Place some other tape over your aluminium tape. This is to insulate the alu-tape from your body.
Tape some aluminium tape below the touch-sensor on the other side of the cardboard. This will be your ground-plane. Attach a wire to this one also, and attach the other end to the GND plug on your Launchpad.
Upload the right code.
Test the buttons. You may have to edit the ‘threshold’ in the structure.c to get the right value for your box.
I’ve placed some example code here, which prints out the capacitative value that the the MCU has found for your sensor on the LCD board I make. If you have some other LCD, you can edit the code. I have two LCD boards, one capacitative and one button-board. This code is really for the button-board, since you have external touch sensors. The main.c file is below if you want to see it:
Up to now I have run an ad-free site, but I need to move to a better server so have to get some income on the blog. I hope people feel it’s ok with the level of ads that is here now. If not let me know and I’ll change it. Thank you very much for reading the blog and I hope you find it useful and interesting.
John asked a question about how to control motors from an MSP430, so I thought I’d make a post about it. This is a post-in-progress, since I’m at home looking after my baby boy and he won’t let me write much continuously. If you have suggestions to where it should be improved, let me know and I’ll add stuff.
First choose motor type. If you use modified servos, you can just connect them to your microcontroller (MCU) and upload the right code. If you use plain DC motors you need a motor driver chip or board, such as the L298. You probably want geared DC motors, since they aren’t as fast as non-geared ones. Connect the driver to your MCU and upload the right code. The speed of the motors is controlled using pulse-width-modulation.
Software-wise you can either choose Arduino (or the MSP430-equivalent called Energia) or go for the C-approach. C is more difficult, but maybe more powerful. Arduino/Energia works great for many robots and I used this for several years before I moved to C as a programming platform.
Read on if you’re interested. More details and instructions below.
On the garage-end of my garage-door-opener, I need a relay that’s controlled by the wireless key. The relay should be on for a second or less, and this triggers the garage door opener to either open or close the door. I’ve now made this component using a MSP430 Launchpad with a CC2500 Boosterpack on it. The relay is a relay board from Dealextreme. I’m using the 5V holes just next to the USB connector on the Launchpad to feed the +/- on the relay, and an MCU pin to feed the control signal.
I’ve also ordered a bluetooth module from Dealextreme (I have one in my lab, but can’t find it), which I’ll use to implement a smart-phone-app that opens the garage door.
My kids built this one themselves. It’s using the Lego Mindstorm module, two motors, a proximity sensor and a colour LED. The mindstorm module is programmed to wait for someone to walk in front of the sensor, and then move the arms up and down, flashing the RGB LED. Fun and relatively simple project.
This week my lab partner from university and good friend Simon is visiting me in Norway. We of course needed to have a good project to do where we could do a bit of electronics, soldering, radio and mechanics, and building another quad seemed like a good case. I earlier got the KKController from Hobby King. It’s a really excellent product and although there now is a version with accelerometer and an LCD display that makes it even better, the version I have should work.
So we designed a laser cut frame and cut it out of plexiglass. More info below.
I was away for a week’s holiday and it seems my server took a holiday also. It has been really stable the last year without any problems, so it’s typical that it stops the day I leave for holiday. Anyway, it’s back now.