topic Re: Clarification on RTS/CTS Mapping on i.MX93 in i.MX Processors

Clarification on RTS/CTS Mapping on i.MX93

hamzaatifi — Wed, 12 Feb 2025 09:41:08 GMT

Hello,

I am working with UART on both i.MX93 and i.MX8M Plus and facing an issue with RTS/CTS connections.

On i.MX93, the following wiring works correctly:

TX → RX (RS232)
RX ← TX (RS232)
CTS → RTS (RS232)
RTS ← CTS (RS232)

However, on i.MX8M Plus, this wiring does not work. It only works if I swap RTS and CTS.

Additionally, I noticed that the Reference Manual for both i.MX93 and i.MX8M Plus states:

CTS_B = Input (i.MX93)
RTS_B = Output (i.MX93)

CTS_B = Output (i.MX8M Plus in DCE)
RTS_B = Input (i.MX8M Plus in DCE)

But in the Pinmux config tool 24.12 I see:

CTS_B as Output (i.MX93)
RTS_B as Input (i.MX93)

CTS_B as Input (i.MX8M Plus in DCE)
RTS_B as Output(i.MX8M Plus in DCE)

My questions:

Is the RTS/CTS mapping on i.MX8M Plus different from i.MX93?
Is there a known discrepancy between the Pinmux tool and the Reference Manual?

I appreciate any clarification on this issue.

Thanks in advance!

Best regards,
Hamza

Re: Clarification on RTS/CTS Mapping on i.MX93

danielchen — Thu, 13 Feb 2025 16:10:42 GMT

Hi Hamza

Let me check it on my side, will get it back to you once I have any results.

Regards

Daniel

Re: Clarification on RTS/CTS Mapping on i.MX93

danielchen — Wed, 19 Feb 2025 11:33:07 GMT

Hi @hamzaatifi

1 ) According to i.MX93 RM, RTS is output and CTS is input. while in iMX8MP RM, CTS is output and RTS is input. They are using different naming conventions.

2) Unfortunately, the direction in config tools for both SOCs are inverted. An internal ticket was created for this.

Thank you very much for your feedback.

Regards

Daniel

Regards

Daniel

Re: Clarification on RTS/CTS Mapping on i.MX93

hamzaatifi — Wed, 27 Aug 2025 07:56:08 GMT

Hi @danielchen,

After updating to the latest MCUXpresso config tools v25.06, we noticed an inconsistency regarding the CTS/RTS pin directions on the i.MX93:

In the Routing Details window, the directions are now correct (CTS = input, RTS = output).
However, if you hover over the muxing options in the Pin List, the directions are still shown incorrectly.

This makes the tool internally inconsistent for the i.MX93.

Could you please confirm if this is a known issue, and whether it will be addressed in a future release?

Hamza