topic Re: LS1020A RCW SPI/UART Signal Multiplexing in Layerscape

LS1020A RCW SPI/UART Signal Multiplexing

sl1 — Wed, 12 Sep 2018 17:07:59 GMT

I'm using the LS1020A and trying to override the RCW so that we can use 2 UARTs (not LPUARTs) and 2 SPIs. Does anyone know if this is possible? In looking at the configuration, it doesn't look like it is possible because there's a conflict between the SPI2 and UART signals. It looks like I can either use SPI2 or UART, but not both for the UART signal configuration. But in the processor block diagram, it does show 2x DUART and 2x SPI. Can someone confirm if this is possible or not?

Re: LS1020A RCW SPI/UART Signal Multiplexing

yipingwang — Fri, 14 Sep 2018 05:27:40 GMT

Please refer to the following RCW definition provided in LS1020 Reference Manual, there is no multiplexing between SPI and UART signals. SPI2 signals and LPUART are multiplexed, SPI1 and IFC signals are multiplexed.

RCW[354-356]

UART_EXT This field configures the functionality of UART pins, together with UART_BASE field.

UART1_SOUT,
UART1_SIN, UART1_RTS_B,
UART1_CTS_B,
UART2_SOUT, UART2_SIN,
UART2_RTS_B,
UART2_CTS_B
Options:
000 See UART_BASE field definition
001 UART1_SOUT, UART1_SIN, LPUART2_SOUT, LPUART2_SIN, LPUART1_SOUT, LPUART1_SIN, LPUART1_RTS_B, LPUART1_CTS_B
010 UART1_SOUT, UART1_SIN, LPUART2_SOUT, LPUART2_SIN, LPUART1_SOUT, LPUART1_SIN, LPUART4_SOUT, LPUART4_SIN
011 UART1_SOUT, UART1_SIN, , SPI2_SOUT, SPI2_SIN, SPI2_PCS0, SPI2_PCS1, SPI2_PCS2, SPI2_SCK

100 UART1_SOUT, UART1_SIN, 2D-ACE_HSYNC, 2D-ACE_VSYNC, LPUART1_SOUT, LPUART1_SIN, LPUART1_RTS_B, LPUART1_CTS_B
Settings not shown are reserved.

RCW[402-404] IFC_GRP_G_EXT

This field configures the
functionality of Group G of the
IFC pins: IFC_AD[8:15]
Options:
000 IFC_AD[8:15]

001 SPI1_PCS1, SPI1_PCS2, SPI1_PCS3,
SPI1_PCS4, SPI1_PCS5, SPI1_SOUT, Reserved,
Reserved
Settings not shown are reserved.

Have a great day,
TIC

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Re: LS1020A RCW SPI/UART Signal Multiplexing

sl1 — Fri, 14 Sep 2018 15:50:59 GMT

I did see this but my problem is that I'm trying to use two SPIs and two UARTs. I did configure SPI1 and UART1, but if I configure SPI2, then I'm unable to configure a second UART. For RCW[354-356], I've set it to be 011 which gives me UART1_SOUT, UART1_SIN, SPI2_SOUT, SPI2_SIN, SPI2_PCS0, SPI2_PCS1, SPI2_PCS2, SPI2_SCK. So now I have two SPIs (SPI1 on the IFC multiplex) but only one UART. I need a second UART.

How can I get a second UART? Or am I not interpreting the RCW configuration correctly. How can I use UART2, UART3, or UART4 with SPI2?

Thanks.