New Project: Convo

Again - not really a new project at all, it just takes me ages to get around to updating this thing.

Awkward silences suck. Whether you're meeting your girlfriend's parents for the first time or making a tasteless joke at a funeral - the threat of a momentary pause in the conversation is an ever-present threat for the not-quite-entirely-antisocial engineer. Unavoidable? Not any more! Introducing Convo, the conversation-starting robot!

The circuit will be relatively simple - one or two minature microphones with amplifiers, a simple microcontroller (I'm using a PIC at the moment, but may switch to the new Value line of MSP430s when my dev kit arrives) with an ADC module, a CompactFlash or MMC card, and a small speaker and amplifier.

The flash card will be loaded with a large number of conversation-sparking sound clips ("How's about them current affairs?!"). The microcontroller will listen out for awkward conversation pauses using the microphones and play a random sound clip when one is detected. It should all be fairly easy to implement, I hope - although it may turn out to be very hard/impossible to get the actual awkward silence detection algorithm working well in all circumstances.

So far I have built the microphone and input amplifier circuit and connected it to a PIC16F819 via a very simple short-term smoothing circuit made from a capacitor and diode. The PIC constantly samples the smoothed output and turns on an LED when it's above a certain level.

Video:


There's only one bug at present - Convo appears to be generating awkward silence. Whenever I explain the idea to someone, my explanation is invariably followed by an extremely awkward silence. I'm not sure why...

Two Good Things

Two Good Things have happened!

1. MSP430 development board for $4.30
Texas Instruments have a new value line of MSP430 processors that seem to be targetting PIC users. They're 16-bit, pretty cheap, and available in DIP packages. Best of all, they're doing "LaunchPad" development boards for a ridiculous $4.30. It includes two of new the MSP430 chips, and they're currently doing free shipping as well. Sadly mspgcc doesn't support them yet, but both TI's Code Composer Studio and IAR's Embedded Workbench have free editions available that are effectively unlimited for the value line chips (they impose a maximum program size, but it's larger than the ROM available on these chips anyway).

The only down-side is that they appear to be on quite a long back order. I ordered mine a couple of weeks ago and was told that they were currently out of stock. No news since, so I think I'll be waiting quite a long time. For about £3, I'm not complaining.

2. A new free PCB design tool
RS Components have released a free PCB design tool called DesignSpark. I've had real problems finding good free PCB design tools, but from the brief play around I've had this one looks excellent for hobbyist use. The user interface in particular seems simple and clean, especially compared to some of the other tools I've tried (Target 3000! comes to mind...) Definitely worth a look.

Train controlling points

As usual, I got this working ages ago and have only just gotten around to writing about it here. I've figured out how to transmit using the CC2420 on the tMote and can now send messages from the train to the points! The train is now running autonomously on a little schedule I've hard coded. It moves to one end of the tracks, sets the points, moves the end of the branch and then back, sets the points to the other branch and moves there, before returning to the start and repeating. Not the most exciting thing in the world, but a big step forward because the train is now autonomously moving about and controlling the points wirelessly itself.

Here's the obligatory dull video!