Yesterday morning I awoke to read my emails and find out the happy news that I had won something in the 555 Contest. No I wasn’t a finalist, but I was fortunate enough to score a lucky door prize.

It’s a 381676 Pen Meter from Extech sporting autoranging, a 2000 count display, non-contact voltage measurement, AC/DC voltage, resistance, continuity, and a diode test mode.

Many thanks to the organisers of the 555 Contest for all their hard work. Thanks also to Extech for sponsoring the event and for the great prize.

In case you’re interested, you can read all about my 555 Contest entry here.

Having cultivated a bit of an interest in robotics over the past few months, I bit the bullet and ordered a Sharp GP2Y0A21YK Infrared Proximity Sensor. This produces an analog voltage output that varies in relation its distance from objects in its sight. Here’s what it looks like (mounted atop a stepper motor):

I needed a circuit to test it out, so here’s what I came up with:

I needed a simple circuit to test an SG90 servo I purchased from DealExtreme. This was the first time I’d experimented with a servo.

I found this servo driver circuit and decided to lay it out on perfboard (aka stripboard, veroboard, etc.):

I thought I’d post the layout in case anyone else wanted to build it up. I produced the layout in LochMaster, a stripboard layout program that has some nice features.

I have now amassed quite a few LaunchPad and EZ430-F2013 development boards from Texas Instruments.

At base these boards seem to do substantively the same thing, just in different form factors. The bundled microcontrollers also appear to have similar capabilities, differing only in terms of certain peripherals.

Add to this the long names these micros have and it becomes a little confusing to remember the capabilities each has. So here is my little cheat sheet:

LaunchPad comes with:

• MSP430G2211IN14: 2kB Flash, 128B RAM, 10 GPIO, 1x 16-bit timer, WDT, BOR, Comparator A+.

• MSP430G2231IN14: 2kB Flash, 128B RAM, 10 GPIO, 1x 16-bit timer, WDT, BOR, 1x USI (I2C/SPI), 8ch 10-bit ADC

EZ430-F2013 - MSP430 USB Stick Development Tool comes with:

• MSP430F2013: 2kB Flash, 128B RAM, 10 GPIO, 16-Bit Sigma-Delta A/D, USI for SPI/I2C.

• MSP430F2012 (from the 3x target board kit, sold separately) : 2kB Flash, 128B RAM, 10 GPIO, 10-Bit SAR A/D, USI for SPI/I2C.

This post describes my entry in the 555 contest. I was poring over the various configurations of the 555 - astable, monostable, delays, inverters, bi-stables, PWM circuits, etc. - and got to thinking whether the 555 (or many 555s!) could be used to generate an asynchronous serial bit stream.

The brief was to create a circuit with 555s as the only active components that would endlessly put out the character “5” as a valid asynchronous serial stream at 9600 bps with 8 data bits, no parity, and one stop bit (8N1). Optionally, the circuit could support sending characters other than the ever so apt character “5”. This is what I came up with:

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