Monday, October 19, 2015

Make your own mini downloader AT89S51 using Parallel interface

Newest downloader is so practical and simple. But, it’s better for us to try mini downloader for AT89S51 using parallel port. The figure are displayed is illustrate only for the downloader is like. When you are change to another shape, it’s no problem. The IC is easy to get and find in electronic component shop. The making is easy, you don’t have to order the PCB which offered in  cm-square. Because the circuit is very simple.
Yup, you are right, you can download the circuit in the internet or a copy from your friend. For me, I tried as like published in the internet. The first time, I using parallel port which is include on the desktop PC.

The circuit is simple, just need x-tal 12MHz, capasitor 30pF. +5V VCC is use USB port.
Figure 1. Mini downloader

Figure 2. USB cable power
Component needed:

These circuit is tried for AT89S51/52 is always work. Although the connection is direct to LPT port behind PC. For the supply just connect to USB port, use USB cable and cut at the other side, and attach housing 2 pin.  

The schematic is here.

About LPT connector, use DB25 male. in order match on the desktop connector. 40 pin socket is for connecting the IC and any module. 40 pin are set as like the Micro pin configuration. The function is for plug and play without release the IC. And the software, you can download it in the internet or you can contact to my mail, I’ll send it to you.
And for the training module, you can make it you self or use your imagination for the input and the output. The examples are going to describe on the next session. This time, we just making the downloader.
- 1 pcs mikro AT89S51
- 1 pcs x-tal 12MHz
- 2 pcs capasitor 33pF
- 1 pcs capasitor 10uF
- 1 pcs LED + resistor 100ohm.
- 1 pcs socket 40 pin male.
- 1 pcs DB 25 male.
- 1 pcs PCB make your own (etching your self

Good Luck


  1. Can you tell me the pin of Db25, which is used for connect AT89s51 ,..what is the function of this pin..??

    1. Thanks for reading.
      pin of DB25 is shown in figure 3. paralel port is same as DB25. which is komputer output port (LPT).
      this function is for ISP programming.
      the pin as like MISO, MOSI, Gnd, RESET and Clock.