Archive for the ‘sprinklino’ Category

Gypsum Sensors Completed

So I went a slightly different route to build the soil moisture sensors as I wasn’t having much luck with the drinking straw method (too fiddly).

My solution was to drill a hole between two pieces of MDF with a flat bottomed forstner bit and then to drill two smaller holes into the bottom of it where the wires would go.

The two pieces clamped together made a really nice mold for the plaster of paris and I could ensure that the wires were a consistent distance apart. I covered the surfaces with vaseline so that the two sides of the mold would seperate easily.

I’ll post pictures of the sensors later today. But it worked really well.

Successful Test of VirtualWire

So I got my TTL RS232 converter from Modern Devices which enabled me to finally fire up my BBB with the VirtualWire transmitter software running on it, with my Arduino Diecimila running the receiver, and it worked flawlessly :) I need to get another breadboard so I can start doing some range tests with it (and play with antenna design) but so far so good and so much cheaper than the XBee modules :)

Multiplexer Test

So tested out the CD4051B 8 Channel Multiplexer today and everything worked as expected. I’m using a multiplexer so that I can use more sensors than I have digital i/o pins.

It’s very simple to use, you send the chip a 3 bit address, and that is the pin that is connected to the output.

To get the Arduino to select each input in turn I did a loop and wrote value directly to the port data register PORTD

void loop() // run over and over again
for(int i = 0 ; i <= 16 ; i++)
byte b = (byte)i << 2; // Shift to the left so that I don't mess with pins 1 & 2
PORTD = b; // Write bits to the i/o pins

I have my LED resistor connected to the common pin so that I only need to use one, and LEDs connected to all the output pins, et voila disco lights :)

Although you can’t see it in this pic the leds are being lit one after another. You can also see the RX4 ASK receiver in this pic but it isn’t hooked up yet as I’m waiting on the TTL/RS232 converter to arrive to program my other Arduino which will control the transmitter.

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