Commit ad97a46b authored by Chipp Jansen's avatar Chipp Jansen Committed by node
Browse files

Update on Overleaf.

parent 3c2f2a81
......@@ -487,11 +487,11 @@ In order to communicate properly, the Data Transmit (TX) on the NEOS needs to be
\caption{Wired connections between NEOS and Raspberry Pi}
\end{figure}
% TODO - probing possible debug ports on the device.
\paragraph{Mind the Voltage} An important thing to consider here is the operating voltages of the boards. The Raspberry Pi's I/O and board operates at 3.3V (which is a common voltage for modern IoT devices). The NEOS also operates at 3.3V. However, older devices might run at 5V (like Arduino boards). You can use a multi-meter first on the device to see at what voltage level the board is powered at. If you have different voltages, you'll need to add \textit{level-shifters} to the UART lines.
\paragraph{Mind the Voltage} An important thing to consider here is the operating voltages of the boards. The Raspberry Pi's I/O and board operates at 3.3V, which is a common voltage for contemporary IoT devices. The NEOS also operates at 3.3V.
However, older devices might run at 5V (like Arduino boards). You can use a multi-meter first on the device to see at what voltage level the board is powered at. If you have different voltages, you'll need to add \textit{level-shifters} to the UART lines to match the voltages.
\paragraph{Enable Serial Port} Now on the Raspberry Pi, in a terminal prompt, we will first check that the hardware UART is enabled \footnote{These steps are from the Raspberry Pi documentation at \url{https://www.raspberrypi.com/documentation/computers/configuration.html\#disabling-the-linux-serial-console}}. (You only have to do this once on the Raspberry Pi).
\paragraph{Enable Serial Port} On the Raspberry Pi, in a terminal prompt, we will first check that the hardware UART is enabled \footnote{These steps are from the Raspberry Pi documentation at \url{https://www.raspberrypi.com/documentation/computers/configuration.html\#disabling-the-linux-serial-console}}. (You only have to do this once on the Raspberry Pi).
\begin{enumerate}
\item Start raspi-config: \verb|sudo raspi-config|
......@@ -502,7 +502,14 @@ In order to communicate properly, the Data Transmit (TX) on the NEOS needs to be
\item Exit raspi-config and reboot the Pi for changes to take effect.
\end{enumerate}
\paragraph{Test connection} We will use the program \texttt{screen} to access the serial port on the device. First, we need to give screen the path to the serial port on the RPI, in this case it is \texttt{/dev/serial0}, however, on other systems like your laptop this might be another name, such as ttyS0 or cu0.
\paragraph{Test the connection} We will use the program \verb|picocom| on the Raspberry PI to access the serial port on the device.
First, check whether \verb|picocom| is installed by running \verb|which picocom| in the terminal. (If it is not found, then you can install it by running \verb|sudo apt-get install picocom|.
In order to connect to the
% \verb|screen|
the path to the serial port on the RPI, in this case it is \texttt{/dev/serial0}, however, on other systems like your laptop this might be another name, such as ttyS0 or cu0.
% TODO - check on the Mac serial port name
The other argument that we need to give screen is the speed that the serial port is operating at, which is a \textit{baud} rate. For modern systems, 115200 is a good starting point \footnote{9600 is another common baud rate. For more common rates \url{https://en.wikipedia.org/wiki/Serial_port\#Settings}}. In general, you will get some sort of output, but if the baud rate is wrong, then you'll get random characters. A more sophisticated approach would be to measure the speed of the output lines with an oscilloscope.
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