I have a Max 202 Ic and Max 232 Ic

I currently want to make a USB to RS232 Serial Db9 converter

i have the db9 male port, a max 232 and max 202 , usb female port and bunch of other passive components .

Is it possible to make a USB to DB9 Rs232 converter ? if yes , how ( any schematics ) ?

PS : also what is an alternative IC circuit to make USB to RS232 db9 , if this is not possible , ( i have this for my college project )

image : this is the project flow , as u can see at starting I need to make a USB to rs232 male DB 9 converter and this thread is about that

enter image description here

  • 1
    \$\begingroup\$ Check FTDI ICs e.g. FT232. \$\endgroup\$ May 30, 2021 at 3:58
  • \$\begingroup\$ @RohatKılıç I have checked the FTDI IC , but its in SOC pin out , Any ICs in DIP config ? \$\endgroup\$ May 30, 2021 at 3:59
  • \$\begingroup\$ Why do you need a MAX232 chip if all voltage levels are below 5V? I thought 232 chips are for shifting the voltage levels and inverting the polarity to match the 12-15V RS232 output of PC to 5V output of the micro controller. And what's with the SPI block in the diagram? \$\endgroup\$
    – AJN
    May 30, 2021 at 4:07
  • \$\begingroup\$ @AJN actually according to the flowchart of my project - the first section , i want to make a USB to RS232 DB9 male converter, i thought a max232 can help me do that , correct me if i am wrong , what should i use ( DIP IC ) to make the USB to RS232 DB 9 male converter? \$\endgroup\$ May 30, 2021 at 4:10
  • \$\begingroup\$ I am not familiar with any DIP IC. But you can see if non DIP IC with breakout board is available. The ic will come pre soldered to a PCB which will have pins that are consistent with DIP. But then, if you use such a board, you will need to expand the scope of your project since the board will solve most of the conversion work for you. \$\endgroup\$
    – AJN
    May 30, 2021 at 4:19

1 Answer 1


To answer your question, no, you can't make a USB to serial adapter with simply onnectors and TTL-to-RS232 tranceiver chips. And most likely no DIP chips exist unless you build a software bit-bang implementation with a DIP MCU, which I also don't recommend.

But you don't have to maka a USB serial port yourself. You can just buy a ready made cable that contains all the electronics to have a USB-to-RS232 adapter.

But if you intend to serially bitbang SPI you can also buy an USB-to-TTL level adapter that has no RS232 transceiver so the TTL levels are suitable to direct connection to TTL level MCU, and you don't need MAX202 or MAX232 transceivers.

These devices exist as DIP modules as well.


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