Interfacing Between Arduino and Delphi

A laptops or computers today rarely have physical parallel or serial port. Everything has been replaced with an USB port that is now in third generation (USB 3.0) with a data transfer speed rate up to 3.2 Gbps. Wow. But unfortunately for interfacing freak, they won’t say 'wow', because data transfer speed is not main factor, but ‘miscellaneous’ only. The important thing is how to release digital logic '1' and '0' exit/enter to the computer to be processed according to the program's objectives.

What is the meaning of 'interfacing' here? Interfacing is such as ‘communication’ between two devices (or more) that works in a digital world (only know the logic '1' and '0') with a controlled object which is usually in analog quantities such as actuators and sensors. Simple example is when you want to move a robotic arm with a computer. Here, the computer acts as a control center and a robot arm as the object of control. How to become a computer with only working on digital logic '1' and '0' to control a robotic arm? That is called 'interfacing' J

Please keep in mind there three items to perform interfacing activity. First, a program that performs all control process in computer, the second is the data exchange, and the last is the port (COM) as the data ‘entrance’. Let us try to examine one by one according to 'interfacing between Arduino and Delphi' case study.

The first: application. For current case study, the application that served as a control center in computer is written in Delphi. Beside Delphi, you can also develop using Visual Basic, C++, Java or others. Why use Delphi? Because it’s one of more popular SDK (Software Development Kit) in the world I loved J.

The second: data exchange. For the data, it could have any kind of data but in binary logical level. I’ll explain it as you go along. The third: port as data entrance. Well, they are most important because as I described in the first paragraph, it’s rarely computer equipped with parallel or serial port for data exchange. One solution is using a converter, either usb to parallel (obsolete too) or usb to serial. One of them is using a microcontroller to act as 'slave' that translates command from computer simultaneously. Another is using V-USB technique by issuing data to a USB port via libUsb driver. This method requires a microcontroller burned V-USB firmware. The difference, first technique actually using USB data frames sent to the external device, unlike the second option that converts into a classic serial protocol into USB payload. Okay, for easier we will choose second method and using Arduino as serial-ready board.

Interfacing Arduino-Delphi Block Diagram

Here is interfacing between Arduino and Delphi block diagram. I hope the picture below can illustrates what is ‘interfacing’ and how to do that.

Preparation on Arduino Side

For experiment, prepare an Arduino Uno, USB cable (type-B) and a PC / laptop. For example,  we will try to turned on/off internal LED that exist in Arduino Uno board (pin numbers 13) controlled by a executable application in laptop (written in Delphi). This program is intended as a simple representation of 'interfacing' in digital to analog world. Then, you could develop it for more complex applications, such as connects Arduino to other actuators (ex: motor driver for moving a robot arm). Here are all steps to on/off internal LED Arduino board on pin 13:

Upload Arduino sketch as follows to handle serial communication. The essence of this sketch is to process incoming serial data to Arduino and then turned on/off LED as corresponding command immediately

void setup() {
pinMode(13, OUTPUT); 
digitalWrite(13, LOW);

void loop() {
if (Serial.available()) {
 char command =;
 if (command=='0'){
  digitalWrite(13, LOW);
 if (command=='1'){
  digitalWrite(13, HIGH);

Preparation on Computer Side

We need prepare our computer in order to have ability to send or receive data to Arduino. We can’t control some loads directly using computer. We need Arduino to ‘translates’ our command in serial data to ‘parallel’ data to the loads.

Here we go. First, install Delphi and TComport component. This component is used to communicate with other devices through serial port, either in physical or virtual serial ports they are. As notice, you should install the right TComport with Delphi version in order to work properly. For example, for Delphi XE2 below you can install TComport 3.1 but for Delphi Xe3 above you must install TComport 4 or newer.

In installer file of TComport, there is ComExample.dpr file in ‘Examples’ folder. Open the file within Delphi, then execute by pressing F9 key. You can make your own program, but I recommend to using this example program for first time, so if you meet a problem, it’s not caused by the Delphi (perhaps a cable connection or on Arduino side).

Press ‘Settings' button, then enter COM port belongs to Arduino USB (you can see in 'Control Panel-System-Device Manager') and enter baudrate at 9600 bps. Then press 'Open' button to start opening serial port connection to Arduino.

Further, input numeric character '1' in edit box above 'Send' button and see the changes on Arduino board. There should internal LED will continue lights on there. Next, try to enter '0' character in edit box and press the 'Send' button. The LED is supposed to be lights off.

Done. Please keep in mind, we just did a low level interfacing programming which means we also need to know electrical characteristics of the hardware. In example above, we tried to transfer commands from laptop to turn on/off Arduino’s internal LED, with intermediary of USB cable. Well, if you have any questions please fill comment out below.
Next Post »