topic i.mx6 uart hardware flow control RTS/CTS in i.MX Processors

i.mx6 uart hardware flow control RTS/CTS

shanxigjz — Mon, 07 Jul 2014 09:09:25 GMT

Hi all

I want to use UART2 for BT module, the BT module have RTS/CTS.

UART2_TXD----------->BT_UART_RX

UART2_RXD<-----------BT_UART_TX

UART2_RTS----------->BT_UART_CTS

UART2_CTS<-----------BT_UART_RTS

My uart2 configuration in kernel as bellow:

static const struct imxuart_platform_data mx6_uart1_data __initconst = {

.flags = IMXUART_HAVE_RTSCTS | IMXUART_USE_DCEDTE | IMXUART_SDMA,

.dma_req_rx = MX6Q_DMA_REQ_UART2_RX,

.dma_req_tx = MX6Q_DMA_REQ_UART2_TX,

};

imx6q_add_imx_uart(1, &mx6_octpath_uart1_data);

But, after doing this, the UART2_RTS pin is always high, which should be low i think to tell BT module to send data.

Is there other setting for this?

Thank you.

weidong_sun — Tue, 08 Jul 2014 02:12:16 GMT

Hello Jianzhong,

Please see following suggestions!

1. Please check if UART2 multiplexing is correct.

2.if you didn't still resolve the issue, would you please provide the following information?

(1) schematic of UART2 on CPU side.

(2) All source code on UART2 configurations including IOMUX

the source code you submitted was not complete, so please give me a part of complete source code on UART2.

In addition, I have to remind you signal io directions of UART:

UART2_TXD-----------Output

UART2_RXD-----------Input

UART2_RTS-----------Input

UART2_CTS-----------Output

I feel your connections on hardware are not correct, please check it !

Regards,

Weidong

shanxigjz — Tue, 08 Jul 2014 02:31:42 GMT

The schematic parts of uart is as bellow.

And bellow is the uart source code.

/* source in XXXboard.c */

static const struct imxuart_platform_data mx6_uart1_data __initconst = {

.flags = IMXUART_HAVE_RTSCTS | IMXUART_USE_DCEDTE | IMXUART_SDMA,

.dma_req_rx = MX6Q_DMA_REQ_UART2_RX,

.dma_req_tx = MX6Q_DMA_REQ_UART2_TX,

};

imx6q_add_imx_uart(1, &mx6_uart1_data);