topic Re: i.mx6: question in i.MX Processors

i.mx6: question

jfsimon — Thu, 14 Mar 2013 14:33:56 GMT

Hi,

On our i.mx6DL based design, we have the following IOMUX settings for UART2:

UART2_RX ----> goes to PAD SD4_DAT4

UART2_TX ----> goes to PAD SD4_DAT7

The routing from signal to pad is easy...just set the following MUX registers:

37.3.208 Pad Mux Register (IOMUXC_SW_MUX_CTL_PAD_SD4_DATA4) ---> ALT2

and

37.3.211 Pad Mux Register (IOMUXC_SW_MUX_CTL_PAD_SD4_DATA7) --->. ALT2

So far so good.

Now, since these two signals (UART2_RX and UART2_TX) can be driven by different PADs, we need to use a select input register. The problem is that there is a UNIQUE input register for the two signals. Specifically:

IOMUXC_UART2_UART_RX_DATA_SELECT_INPUT (section 37.3.572 in the user manual) (See picture)

So how can we correctly select the input for these two signals?

Thanks a lot

-jf simon

Re: i.mx6: question

YS — Thu, 14 Mar 2013 16:20:12 GMT

Refer to iMX6 Reference Manual 35.2.3 "Daisy Chain". IOMUX_INPUT register is used to select a particular source for a function module input. In this case, RXD of UART2. It is confusing that IOMUX_INPUT provides selection to choose TXD as input source. This is only used for loop-back test. So in your case, configure 110 to select SD4_DAT4 as UART2 RXD input will work fine.

It is more confusing for RTS/CTS, because iMX6 (and iMX5) defines RTS as input and CTS as output, which is usually used in opposite way (in fact iMX28 defines RTS as output, CTS as input).

Re: i.mx6: question

jfsimon — Tue, 19 Mar 2013 17:56:03 GMT

Hi Yuji,

Thanks a lot for y answer

-jfs