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Chris Esposito 2018-02-06 14:36:11 +11:00
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@ -28,52 +28,6 @@ If you’re familiar with electronics lab equipment, you can also skip most of t
Apart from that, enjoy! Let’s move on.
## Connecting Your Labrador to a Breadboard
![image_1](https://user-images.githubusercontent.com/22040436/35839080-95ad4e64-0b42-11e8-86e7-644dbfbf6564.png)
(image credit: Gianpaolo Macario)
You can connect your Labrador board as shown above. Power supply pins should go in the side rails to prevent any shorts.
Of course, if you don’t have a breadboard handy, the board can also be used without one. But where’s the fun in that?
## Connecting Your Circuits to Labrador (WIP)
There are a few important things to keep in mind when using your Labrador board:
* Labrador is a *collection of independent tools *that happen to share a single connection and software interface. Apart from small amounts of unintended crosstalk, there are no internal connections between Labrador’s different instruments!
* All voltages are GND-referenced, with the exception of the multimeter which measures CH1 referenced against CH2. If your oscilloscope measures 5V, it means that the voltage at the node your oscilloscope pin is connected to is 5V higher than the Labrador’s GND pin (NOTE: In Electrical Engineering there is no such thing as an "absolute voltage" at all; only how much higher or lower the voltage at one particular node is compared to another. A 1.5V battery doesn’t “have” 1.5V; it just means that the positive terminal is 1.5V higher than the negative terminal.). Make sure you connect the GND point of your circuit under test to Labrador’s GND pin!
* If you don’t know what AC coupling is, don’t use the AC-coupled pins. Use the DC-coupled pins instead as they don’t alter your signals.
* Labrador is idiot-proof. You should be able to short any two pins together without damaging your board, and even if you do something like connecting a 12V external power supply directly to one of your digital output pins, they’ll nobly sacrifice themselves to ensure the rest of the board will still function (and you can fix it by replacing a single resistor). Experiment a bit! You can’t do too much wrong.
* Labrador is idiot-proof, but not complete-idiot-proof! If you start touching live wires to random components on your board, I cannot guarantee what will happen. Please make sure you **only connect your circuits to the external header pins**, and don’t dangle live wires near the microcontroller!
## A Simple Circuit Example
The simplest circuit I can think of is the voltage divider:
![image_2](https://user-images.githubusercontent.com/22040436/35839083-996f4cfa-0b42-11e8-9bc0-aa796d82fdb0.png)
It transforms the input voltage Vin to the output voltage Vout according to the equation:
For example, if you used a 1k resistor for R1 and a 10k resistor for R2, the voltage at Vout would be equal to 10/11ths of the voltage at Vin.
I tested this theory in real life by building the voltage divider and connecting it to Labrador!
You can do the same. If you’ve not dealt with oscilloscopes or signal generators before, it’s the best place to start.
![image_3](https://user-images.githubusercontent.com/22040436/35839086-9b8ae602-0b42-11e8-8111-a5a5922af8d8.jpg)
Above is a picture of my breadboard. The oscilloscope CH2 pin is connected directly to Vin with a standard solid-core jumper wire. The oscilloscope CH1 pin is connected to Vout. The GND node of the voltage divider is connected to the GND pin of the Labrador (NOTE: If you’re not familiar with how the connections in a breadboard work, I recommend checking out Adafruit’s tutorial. I also recommend tearing the backing off of a breadboard at least once in your life. Just make sure you have duct tape handy to put it back together again.). Vin is connected to the signal generator CH1 DC output. The resistors used were both 6.8k, meaning that the voltage at Vout should be approximately half (NOTE: I say "approximately half" because no component is 100% accurate. The resistors I used have a tolerance of +/- 1%, meaning that the actual resistance could be anywhere between 6.73k and 6.87k.) the voltage at Vin. You can do the maths if you don’t believe me.
![image_4](https://user-images.githubusercontent.com/22040436/35839090-9f656a9a-0b42-11e8-8173-08870d1601ff.png)
Above is a picture of my Labrador’s software interface. I used the signal generator to output a 3V sin wave. As you can see, the yellow trace (oscilloscope CH1), is half the height of the blue trace (oscilloscope CH2). Thus, the voltage at Vout is half of the voltage at Vin!
# Firmware and Bootloader Mode
Each version of the software interface is compatible with a specific version version of the board firmware. If there is a mismatch, then the software will automatically flash the required firmware and continue.