1/28: Lab 1: Getting Started With LogoChips

in which Julia revisits PicoBlocks to interface with simple circuits

Breadboard-computer connection:
wires through a microchip to a
USB cable.

Today we began our adventures assembling programmable circuitry with solderless breadboards!  After spending many hours as a small child delightedly wiring batteries to power small fans and miniature lightbulbs, this was a source of much personal joy.  I was especially enthused to interpret the pins of the microchip, as last semester I studied an IC chip for a materials science course at Olin (the source of the background, an SEM image of a 555 Timer IC).  In this first introduction we interfaced with the circuit via the simple programming language PicoBlocks and a LogoChip; as shown below, we used several resistors and capacitors (as well as some switches) to change the color and brightness of a red-green bicolor LED.

A simple LogoChip circuit to regulate current to the LED--can be programmed to brighten, dim, or flash LED.

 With a similar circuit, we were later able to monitor the current flow with an oscilloscope.  Adding a voltage regulator kept the voltage at about 2.5 V, the optimum level for the LogoChip (instead of the 3.3 V from fresh batteries).  Adding a photosensor (which changes resistance depending on the incident photons) allowed further creativity in programming; we were able to match the computer's output from the photoresistor (measured via the input gate of the LogoChip) with the oscilloscope's current flow readings.

Adding the voltage regulator, photosensor, and oscilloscope leads to monitor the current.

Next lab: Thevenin's Good Idea--voltage dividers and fun with motors!