Analog Inputs - Hardware¶
Note
This section covers analog input hardware. For a software guide to analog inputs, see Analog Inputs - Software.
An analog signal is a signal whose value can lie anywhere in a continuous interval. This lies in stark contrast to a digital signal, which can take only one of several discrete values. The Systemcore’s analog input ports allow the measurement of analog signals with values from 0V to 3.3V.
Important
Systemcore Analog Inputs are 3.3 volts, whereas the roboRIO was 5 volts.
In practice, there is no way to measure a “true” analog signal with a digital device such as a computer (like the Systemcore). Accordingly, the analog inputs are actually measured as a 12-bit digital signal - however, this is quite a high resolution [1].
Analog inputs are typically used with sensors that produce continuously varying measurements. Potentiometers are a good example, as they can communicate by outputting a voltage proportional to their measurements.
Connecting to Systemcore analog input ports¶
Warning
Always consult the technical specifications of the sensor you are using before wiring the sensor, to ensure that the correct wire is being connected to each pin. Failure to do so can result in damage to the sensor or the RIO.
Warning
Never directly connect the power pin to the ground pin on any port on the Systemcore! This will trigger protection features on the Systemcore and may result in unexpected behavior.
The Systemcore has 6 Smart I/O ports (numbered 0-5), as seen in the image above. Each port has three pins - signal, power (“3.3V”), and ground (“gnd”). The “power” and “ground” pins are used to power the peripheral sensors that connect to the analog input ports - there is a constant 3.3V potential difference between the “power” and the “ground” pins [2]. The signal pin is the pin on which the signal is actually measured.
Connecting a sensor to a single analog input port¶
Note
Some sensors (such as potentiometers) may have interchangeable power and ground connections.
Most analog sensors will have three wires - signal, power, and ground - corresponding precisely to the three pins of the Smart I/O ports. They should be connected accordingly.
Todo
Update above image to use the Systemcore Smart I/O ports.
Connecting a sensor to multiple analog input ports¶
Some sensors may need to connect to multiple analog input ports in order to function. In general, these sensors will only ever require a single power and a single ground pin - only the signal pin of the additional port(s) will be needed. The image below is shows an analog accelerometer that requires three analog input ports, but similar wiring can be used for analog sensors requiring two analog input ports.
Todo
Update above image to use the Systemcore Smart I/O ports.