DrawBot XY Plotter with Arduino GRBL Controller

In this article, I would like to discuss about using DIY XY plotters which are also called draw bots. You can buy them at online stores such as LYCNC store or Global Tech. Factory Store on Aliexpress.

• Overview
• Controller
• Calibration
• Drawing

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.

MCP3008 - Analog to Digital Converter with SPI Interface

MCP3008 is an 8-channel, 10-bit analog to digital converter from Microchip.

Figure. MCP3008 pins.

It can be used as 8 single ended analog inputs or 4 differential input pairs. Power supply is 2.7 V to 5 V and its operating temperature is -40 °C to +85 °C. It has an SPI interface which can be operated in mode 0 or mode 3.

Pixy

Pixy (http://cmucam.org/projects/cmucam5) is a vision system that can be used to add computer vision to your Arduino, Raspberry Pi, or BeagleBone project. Once you have taught it the color to detect, it can send you the position and size of the detected objects.

TFT LCD Touch Screen - ILI9341

I tested a 2.4 inch 240 x 320 resolution TFT LCD touch screen bought from Aliexpress.

That module has LCD display, touch input, and SD card reader. I have written some example programs to use that module and they are available at the following link.
https://github.com/yan9a/cearduino/tree/master/tft_lcd_touch

Motor Driver - DRV8834

I am designing a motor driver to drive a stepper motor AM1020-V-6-65. At first, I thought to use A4988 from Allegro. But its supply voltage of 8V - 35V is not suitable for a 6V motor, its chip size 5 mm x 5 mm is bigger than what I want. DRV8835 from TI has appealing 2 mm x 3 mm size but it is meant for DC motor and there is no indexer to support convenient control of stepper motors. Finally, DRV8834 with 4 mm x 4 mm size, motor supply voltage 2.5V - 10.8V, and current 1.5A per coil is chosen.

DS1307 Real-time Clock

Using DS1307 Real-time clock is discussed. A module in AliExpress costs only about $1. It even consists of a 32k EEPROM called AT24C32.

Figure. Setup.

Adaptive Filter: BMFLC

In this article, I will discuss about adaptive noise canceling techniques such as

1. Fourier Linear Combiner (FLC)
2. Weighted-frequency Fourier Linear Combiner (WFLC)
3. Bandlimited Multiple Fourier Linear Combiner (BMFLC)

FLC estimates the quasiperiodic signal of known frequency by using least mean square (LMS) algorithm to adapt the amplitude and phase of a reference signal. WFLC is an extension of FLC which can adapt to a periodic signal of unknown frequency and amplitude. Consequently, WFLC also adapts to time-varying reference signal frequencies while FLC can only estimate a signal with fixed and known frequency. To eliminate the time lag which is not desirable in real-time application, a method using combination of WFLC-FLC has been proposed. One limitation of WFLC is its inability to extract a periodic or quasi-periodic signal containing more than one dominant frequency. To overcome that, BMFLC approach tracks a predetermined band of multiple dominant frequencies based on the prior knowledge of the desired signal. The adaption process is achieved using LMS optimization similar to WFLC and FLC. As the frequency components in BMFLC are constant, analytical ouble integration can be employed to obtain the displacement from acceleration. Due to this reason, it becomes an ideal choice for applications where data is sensed with accelerometers.

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Setup

Arduino zero pro is used for the experiment. The code are written in C so that it can be ported to other platforms easily. Firstly, a reference signal is generated which is superimposed with noise. The generated signal is filtered with adaptive filter. The filtered output is compared with the reference signal by plotting them on serial plotter. The latest version Arduino IDE has not only Serial Monitor but it also has Serial Plotter. Therefore, it is easy and convenient to plot and see them serial plotter how an adaptive filter adapts to its input signal.

Figure. A simple setup using an Arduino Zero Pro board.

Gyroscope L3G4200D

L3G4200D is a MEMS ultra-stable three-axis digital output gyroscope made by STMicroelectronics. A L3G4200D Module in Aliexpress costs only about $3.

Figure. L3G4200 Gyroscope module

Controlling Your Hardware from the Web Using Arduino

Using Arduino Ethernet shield 2 to control a hardware from the web is discussed. Arduino Ethernet 2 Library is used to implement in an Arduino Uno board as a server in an example as well as a client in an another example. The latest version Arduino IDE ( 1.7.6 in our case ) is used in the following examples. An Arduino Uno board with Ethernet shield 2 is shown below.

Figure. Arduino Uno paired with Arduino Ethernet shield 2.

Accelerometer LIS3DSH

LIS3DSH is an 3-axis MEMS accelerometer made by STMicroelectronics. Its full scale range is selectable from ±2g to ±16g. The size is small and it is only 3mm x 3mm. Either SPI or I²C can be used to interface with it. Supply voltage is from 1.71 V to 3.6 V. In this article, testing and evaluation of STEVAL-MKI134V1 adapter board is discussed.

Figure. STEVAL-MKI134V1 - LIS3DSH adapter board for standard DIL24 socket.