What is THD and How to calculate THD

THD or Total Harmonic Distortion (THD) is a value that indicates how the system has how much harmonic. When THD = 100% or 1.0 mean the system has 100% harmonic and THD = 0 mean No harmonic in the system.

In sound application, less THD means equipment has accurate, less noise and sound quality is very good.

In Power application, less THD means the system has a minimum loss, low heat loss. This is good for the system.

We can define THD of Voltage and Current by the formula. THD has 2 types of standard.

1) THD definition from IEC standard
Total harmonic distortion, THD (abbreviation) :
The ratio of the Root mean square (RMS) value of the harmonic content of an alternating quantity to the RMS value of the fundamental component of the quantity


Vh is Voltage RMS Harmonic order, Order 2 to Order n

V1 is Voltage RMS fundamental or V order 1 (no Harmonics)

h is an order of Harmonics Order 2 to Order n (h≥2)


Ih is Current RMS Harmonic order, Order 2 to Order n

I1 is Current RMS fundamental or I order 1 (no Harmonics)

h is an order of Harmonics Order 2 to Order n (h≥2)

The THD formula above, which is defined from IEC standard, it has the opportunity for value of THD more than 100% (Harmonicas value are combined more than fundamental order).

2) THD calculation


V is Voltage RMS include Harmonics and Fundamental order

I is Current RMS include Harmonics and Fundamental order

The THD formula, it has no opportunity for value of THD more than 100%. Because the num (include harmonics) has more value than den value.

From THD definition THD is ratio but most people are using THD value as percent and use formula follow IEC standard.

Example of THD calculation (IEC standard)

If Power system has Current Harmonic

Fundamental current = 100 A

5th Harmonic component  =  20 A

7th Harmonic component = 12 A

Current THD  = 0.23 or 23%.

What exactly is an ASIC

ASIC or Application-specific integrated circuit is Chip used for specific application things and they cannot use for general purposes like microcontroller or microprocessor. For Design ASIC, at first use design logic gate for application on FPGA (Field Programmable Gate Array) After that then make ASIC chip. Designers of digital ASICs often use coding to describe the functionality of ASIC for hardware description languages (HDL), such as Verilog or VHDL.

Advantage of ASIC

Power consumption and efficiency are very good because of the design for a specific application.

Price of ASIC chip when productions are the same as MCU.

Disadvantage of ASIC

Feature not flexible.

Difficult to develop and cost too high.

Time to Market is very poor because difficult to develop and need to test confirm before releasing to ASIC chip.

As you can see, the ASIC has advanced on efficient performance but in the disadvantage are take time to develop and not flexible.


Example ASIC chip

SHA256 ASIC for Bitcoin mining

Google Cloud TPU (Tensor Processing unit) for Machine learning application

Tesla Full Self-Driving chip (FSD) for automatic Self-Driving Car

How to Enable SMB1

If you found this error message like this,

You can’t connect to the file share because it’s not secure. This share requires the obsolete SMB1 protocol, which is unsafe and could expose your system to attack. You system require SMB2 or higher.  For more info on resolving this issues see: https://go.microsoft.com/fwlink/?linkid=852747


That means your server file share is requiring SMB1 protocol. But to enable SMB1 is unsafe.  it need to update windows to latest version and then you  can enable SMB1 by follow this, Go to control panel programs and then click “Turn windows features on or off”. Scrolling to SMB1.0/CIFS File Sharing Support, check box SMB1.0/CIFS Client and Server as picture below,


How to use PuTTY for Serial port terminal

This article show how to use PuTTY as a Serial port terminal step by step.

First step at Session category you have to select Connection type to “Serial” and then specify Comport number and speed.

After that at Terminal category Select Local echo Force on and Local line editing Force on

Then Click at Serial is sub category in Connection category, configure detail of Serial port that you use such as Speed, data bits stop bit, Parity and Flow control

Click Open then you ready to use PuTTY as serial port terminal

How to fix SMBus Host Controller not enable in Vmware?

If you install Ubuntu and you found this error massage like this “SMBus Host Controller not enable!” and you want to fix it here is solution,

Edit blacklists.conf by $ sudo nano /etc/modprobe.d/blacklist.conf

And add “blacklist i2c-piix4” on the last line in blacklist.conf

After that reboot your virtual machine by $reboot

Finish, the massage “SMBus Host Controller not enable!” had already fixed.

How to install IAR MSP430

Follow step by step for IAR Embedded Workbench for MSP430 installation.
And these installation are similar to other device of IAR Embedded Workbench.
The Version of IAR on this example, which I install, is 5.60.

Click Install IAR Embedded Workbench

Make sure your remove USB dongles (IAR license USB) from your PCs.

Before we can use IAR, it has to activate license, this process need the internet.

Click Yes, for extract files of IAR Libary Source for 430

Click License then Activate Licese

Fill your license number 12 digit with “–“

If you licese activa correcly, it will show green color on the licese

After finish activate IAR license you can use IAR without internet connection.

We finish install IAR MSP 430 now you can test by compile project, if it work it will can compile.

Recommend WP Super Cache Setting [Part1]

Many people are using WordPress. The must has plugin is definitely “Cache plugin”, which can cache dynamic page to static html page. And one of the popular WordPress plugin is “WP Super Cache”, with downloaded more than 1M. On this article I will show how to setting WP Super Cache correctly and efficiency.


Easy tab: this tab use for quick and easy setting no need to tuning, just click Caching On (Recommended).

Advanced tab: Is you need more efficiency. this is tab for you I will

explain each setting below. (more…)

Understanding MCU vs MPU

Many people have doubt about MCU and MCU, What are different between MCU and MPU?

MCU (Microcontroller Unit, uC)

MCU or Microcontroller, consist of 2 word are Micro and Controller, it mean small controller, small computer which inside microcontroller are Processor, memory, peripheral ADC, Timer, USART, USART or complex module such as AES module. (more…)