Getting Started with FRDM-K82F

FRDM-K82F is a low cost development platform using MK82FN256VLL15 microcontroller. When I started using the board according to its getting started guide at

Get Started with the FRDM-K82F [NXP16],

I found out that its out-of-box demo is not running on my version of FRDM-K82F board. The insturctions on that page are also out of date. And, I could not get it worked.

After spending my time testing, browing the Internet, and experimenting, I found out that the following things might be necessary, in a brief, to make the board worked.

• Debug adapter - update it
• IDE - use MCUXpresso instead of Kinetis Studio
• SDK - use MCUXpresso SDK Builder (make sure to 'drag and drop')
• Flash - unlock the MCU's flash if required

Figure. FRDM-K82F board.

PCF8591 - 8-bit A/D and D/A converter

PCF8591 is an ADC/DAC device with four analog inputs and one analog output. It has an I2C interface with three address pins. The operating supply voltage range is from 2.5 V to 6.0 V. When all three address pins are low, its address is 0x48.

Figure. PCF8591 pins.

Curve Plotting with C++

In this article, some of the tools for plotting curves with C++ will be discussed with examples. They are

• Gnuplot
• Octave
• Matplotlib

Gnuplot

Gnuplot can be installed on Ubuntu using the following commands.

$ sudo apt update
$ sudo apt install gnuplot

Entering the following command starts Gnuplot.

$ gnuplot

Information such as version number for Gnuplot will be displayed and you will be at the command prompt of gnuplot. As a testing, we will plot sin(x) and cos²(x) will be plotted on it again. Thereafter, the plots as illustrated in Figure. 1 should appear [Mig18]. You can enter 'q' to quit Gnuplot.

> plot sin(x)
> replot cos(x)**2
> q

Figure 1. Plotting sin(x) and cos²(x) to test gnuplot.

Using Parallel Port on Linux with C++

Example programs for using parallel port on Linux [Lin15a,Coo08a], and a C++ class library can be found at the following link.

https://github.com/yan9a/cecpp/tree/master/parallelport

Figure 1. wxWidgets example using paraller port as digital output and input.

MySQL Connector/ODBC 8.0 on Linux

Oracle's MySQL server can be connected and used with ODBC driver in a similar fashion that we have discussed for Microsoft's MsSQL server in the previous post. For that, we will use the latest MySQL Connector/ODBC 8.0 driver by building and installing it from the source.

Therefore, the procedure can be used for various SBCs with different architectures. An advantage for this approach is that we can use the same C++ code for both MsSQL server and MySQL server just by changing the DSN. At first, following tools need to be installed in the machine.

sudo apt install mysql-client libmysqlclient-dev
sudo apt install unixodbc unixodbc-dev
sudo apt install libgtk-3-dev cmake
sudo apt install libssl-dev

Using MS SQL Server from C++ with wxWidgets



Using SQL Server with ODBC, C++, and wxWidgets

In this article, we will discuss about using MS SQL server with ODBC API from C++ program. [Eas18]. Thereafter, we will create a class module that connects to SQL server and use it with an example wxWidgets GUI application. For Unix and Linux machines, FreeTDS and ODBC need to be setup as discussed at the following link.

Using Microsoft SQL Server from Linux Machines with ODBC & FreeTDS
(http://coolemerald.blogspot.com/)

Using Microsoft SQL Server from Linux Machines with ODBC & FreeTDS

FreeTDS is a set of libraries for Unix and Linux machines to use Microsoft SQL server and Sybase databases [Fre16]. FreeTDS C libraries are free, opensource, and distributed under GNU LGPL license. In this article, I will discuss about using MS SQL server located on a Windows machine which is installed using mixed mode authentication. The MS SQL server must be configured to allow remote connection with TCP/IP using username and password. That MS SQL server is to be connected and used from a Linux machine using FreeTDS.

MS SQL server is a result of cooperation between Microsoft and Sybase. Therefore, their SQL servers are quite similar and the communication protocols are almost identical. That protocol is called Tabular Data Stream (TDS). The project for open source implementation of TDS is started by Brian Bruns and it is called FreeTDS.

MySQL Connector C++ 8.0 with wxWidgets

Let us discuss about using MySQL Connector C++ 8.0 with wxWidgets. Details about setting up and using wxWidgets, and MySQL server and connector can be found at the following links.

ceMySQL.h Cross-platform C++ programming with wxWidgets

Using MySQL Database with C++ on Various Platforms Including ARM Single Board Computers

For this example, by using MySQL Workbench, we will create a database called 'mytest' and a table called 'mytable' in the MySQL server that is to be connected and used.

Figure 1. Creating a database 'mytest' and a table 'mytable' using MySQL Workbench.

Safe and easy DIY Home Energy Monitor Using Current Transformer with Arduino, Raspberry Pi, or Beaglebone Black

To measure and monitor the energy usage of home appliances, let us build a simple and basic energy monitor. Although there are several methods to build energy monitors, I have chosen YHDC Current Transformer SCT-013-000 [YHD18] for it. Because it is non-invasive, safe, and suitable for learning. It is a split-core current transformer so that it can be fastened and used easily without the requirement to touch the high voltage power lines. Note that only one power cable is to be put in the core as shown in Figure 1.

Figure 1. (Left) SCT-013 is split core so that it can be easily clipped on a wire. (Center) If all the wires are put inside the core, input and output currents are cancelled. Therefore the net current will be zero. (Right) It is required to put only one wire in the core.

DIY Programmable Function Generator Using Arduino Uno

It is possible to use Arduino Uno as a function generator to produce low frequency waveform. The advantage of the approach is the possibility of producing customized, complex, time varying waveform. On the down side, it cannot produce waveform with very high frequencies. To get smoother waveform, the PWM output frequency of pin 3 of Arduino Uno is increased to approximately 8 kHz. It is also possible to use DAC to achieve better results.

Figure. The output of Arduino function generator measured with an oscilloscope.