Which pin is CTS and RTS pins of ST232BTR RS232 transceiver IC?

[KM.11]

Datasheet https://www.st.com/content/ccc/resource/technical/document/datasheet/3c/2a/2e/32/bd/b3/42/11/CD00001703.pdf/files/CD00001703.pdf/jcr:content/translations/en.CD00001703.pdf

[KnarfB]

As that chip is only a level converter, there are no dedicated CTS/... pins. In general, RTS and TxD a transmitters, while RxD and CTS are receivers, see https://en.wikipedia.org/wiki/RS-232. You may find more info by searching MAX232.

[Winfred LU]

Yes. There are no dedicated pins.

ST232BTR is a dual channel transmitters and receivers, used to convert the RX, TX, CTS, RTS signals between TIA/EIA-232 voltage level (can be ±15V) and TTL/CMOS voltage level (3V/5V).

It provides TIA-232 voltage level outputs from a single 5 volt supply by on-chip charge pumps and external capacitors.

Note that the directions are opposite depending on DTE or DCE:

• CTS is an input for DTE and output for DCE
• RTS is an output for DTE and input for DCE

Take a look at STEVAL-PCC001V1 UM. The driver (ST3222EB) being used in the EVB is different, but it provides a reference circuit for the transmitters and receives.

https://www.st.com/resource/en/user_manual/um0323-stevalpcc001v1--getting-started-with-the-st7-fullspeed-usbrs232-evaluation-kit-stmicroelectronics.pdf