USB-RS232 Conversion (FT232RL)

AN405 shows how to interface the FT232BM with a rabbit MCU…I want to use the FT232RL chip, but are uncertain about some changes in the MCU…
-Has anyone successfully interfaced the FT232RL for the same application?
-Is the circuit diagram the same for the RL than for the BM?

We use the FT232RL all the time. Same considerations for power etc. Simpler with no crystal etc. I always compare the datasheets for the FT232RL, FT232BM to see what differences I may need to consider.

Hi Denmansoft,
It seems that you have worked on FT232R(I have read your post on rabbit forum.) I am trying to implement serial to USB & vice versa communication using FT232BM. Can you please guide me whether I have to use all handshaking signals or only RTS & CTS are sufficient for communication? & if these two signals are sufficient then what we have to do with other handshaking signals(ie. DTR, DCD etc.) Is there any good material which I can refer?

Thank you,


Are you using the FT232RL to do FLASH programming downloads as well using the RFU? I have a design using the RCM2020 module - it’s been fine for 8 years but now I want to build in the USB port - unfortunately it’s VERY unreliable at the moment - it works at times but most of the time doesn’t… and it works worse on a Vista/64 computer set to XPcompatibility than on an XP machine.

RS232 is a very basic comms medium. All you often need is 3 lines: Tx,Rx,Gnd. All the rest of the lines are optional and requirements are defined by the software in the devices on each end. Some terminal programs (ie windows Hytpertem) want CTS asserted. Any easy solution to this is to jumper RTS to CTS as these applications will assert RTS and wait for CTS. DSR and DTR are similar in that they are signals telling the other end thay are alive and ready to communicate. DCD is data carrier detect and only used for modems. RI is ring in and only used with modems. I have several books on communications and networking. most cover this stuff. many can be just as confusing after you read them…
We’ve been working with this stuff since the 70’s. so the older books will cover all of this.

Thank you Denmansoft for the guidance.