Function of the DCEDTE bit in the UART of the i.MX6SL MX6

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Function of the DCEDTE bit in the UART of the i.MX6SL MX6

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nathanpalmer
Contributor IV

I am looking for clarification of the function of the UART DCEDTE register value on the i.MX6SL.  The MX6SLEC (Electrical Characteristics) Document says that the DCEDTE bit changes the direction of the RX and TX pins on the MX6SL.  However, the MX6RM (Reference Manual) Document says that the RX_DATA signals are always inputs and the TX_DATA signals are always outputs, regardless of the DCEDTE bit. 

Which pins should I connect to the INPUTs and OUTPUTs of my MAX232 chips if I want to support two separate UARTs in my design, one that is a DCE and one that is a DTE? 

PS: I found some duplicate questions on this forum but none seemed to have definitive answers.

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Yuri
NXP TechSupport
NXP TechSupport

IOMUX (DAISY, etc.) does change the DIRECTION.

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Yuri
NXP TechSupport
NXP TechSupport

  Looks like the problem relates to the fact that the datasheets are referring to the UART + additional

signal multiplexing, occurring between the UART peripheral and the IC pad (at the IOMUXC), while the

Reference Manuals describe only the peripheral boundary (internal signals).

The following Community FAQ may be helpful.

"i.MX6: What does the DTE/DCE in i.MX6's UART do and how are RTS and CTS affected

by the UARTxUFCR[DTEDCE] bit?"

https://community.freescale.com/docs/DOC-97509


Have a great day,
Yuri

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nathanpalmer
Contributor IV

Thanks, I did see that post but I was still unsure.  One last clarification: Does IOMUX (DAISY, etc.) change the DIRECTION of a given pad or does it only affect the signal routing?  In other words, if I wire the PAD UART1_RXD (which appears to be an INPUT based on Table 51-2. i.MX6SL RM) on my board to the INPUT of a MAX232 device, the circuit will not work, regardless of the IOMUX or DCEDTE settings, correct?

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Yuri
NXP TechSupport
NXP TechSupport

IOMUX (DAISY, etc.) does change the DIRECTION.

View solution in original post

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