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Using up to 10 serial ports on RoadRunner SOM
On the Roadrunner is possible to use up to 9 serial ports for user purposes plus the debug serial port.
This article illustrates how to activate at the same time all the ports available.
This article has been tried with a Linux Kernel 4.19.134 and a Debian Buster 10 distribution.
This is pheriperals available to implements the serial ports. When more IOset are listed the peripheral lines can be moved on another set of pins to avoid conflicts with other peripherals.
- UART0 (IOset1)
- UART1 (IOset1 or IOset2) (Used by default as debug port)
- UART2 (IOset1 or IOset2 or IOset3)
- UART3 (IOset1 or IOset3)
- UART4 (IOset1)
- FLEXCOM0 (IOset1)
- FLEXCOM1 (IOset1)
- FLEXCOM2 (IOset1 or IOset2)
- FLEXCOM3 (IOset1 or IOset2)
- FLEXCOM4 (IOset1)
To assign the /dev/ttySx device to each port use this alias list at the beginning of device tree file:
aliases {
serial0 = &uart1; /* /dev/ttyS0 Debug port */
serial1 = &uart2; /* /dev/ttyS1 */
serial2 = &uart3; /* /dev/ttyS2 */
serial3 = &uart4; /* /dev/ttyS3 */
serial4 = &uart0; /* /dev/ttyS4 */
serial5 = &uart5; /* /dev/ttyS5 */
serial6 = &uart6; /* /dev/ttyS6 */
serial7 = &uart7; /* /dev/ttyS7 */
serial8 = &uart8; /* /dev/ttyS8 */
serial9 = &uart9; /* /dev/ttyS9 */
};
UART0
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| URXD0 | I | Receive data | PB26 |
| UTXD0 | O | Transmit data | PB27 |
uart0: serial@f801c000 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart0_ioset1>;
status = "okay";
};
pinctrl@fc038000 {
pinctrl_uart0_ioset1: uart0_ioset1 {
pinmux = <PIN_PB26__URXD0>,
<PIN_PB27__UTXD0>;
bias-disable;
};
};
UART1 (Debug port)
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| URXD1 | I | Receive data | PD3 |
| UTXD1 | O | Transmit data | PD2 |
uart1: serial@f8020000 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart1_ioset1>;
atmel,use-dma-rx;
atmel,use-dma-tx;
status = "okay";
};
pinctrl@fc038000 {
pinctrl_uart1_ioset1: uart1_ioset1 {
pinmux = <PIN_PD2__URXD1>,
<PIN_PD3__UTXD1>;
bias-disable;
};
};
UART2
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| URXD2 | I | Receive data | PD4 |
| UTXD2 | O | Transmit data | PD5 |
| Signal | Dir | Description | IOSet2 |
|---|---|---|---|
| URXD2 | I | Receive data | PD23 |
| UTXD2 | O | Transmit data | PD24 |
| Signal | Dir | Description | IOSet3 |
|---|---|---|---|
| URXD2 | I | Receive data | PD19 |
| UTXD2 | O | Transmit data | PD20 |
uart2: serial@f8024000 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart2_ioset1>;
atmel,use-dma-rx;
atmel,use-dma-tx;
status = "okay";
};
pinctrl@fc038000 {
pinctrl_uart2_ioset1: uart2_ioset1 {
pinmux = <PIN_PD4__URXD2>,
<PIN_PD5__UTXD2>;
bias-disable;
};
pinctrl_uart2_ioset2: uart2_ioset2 {
pinmux = <PIN_PD23__URXD2>,
<PIN_PD24__UTXD2>;
bias-disable;
};
pinctrl_uart2_ioset3: uart2_ioset3 {
pinmux = <PIN_PD19__URXD2>,
<PIN_PD20__UTXD2>;
bias-disable;
};
};
UART3
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| URXD3 | I | Receive data | PC12 |
| UTXD3 | O | Transmit data | PC13 |
| Signal | Dir | Description | IOSet2 |
|---|---|---|---|
| URXD3 | I | Receive data | PC31 |
| UTXD3 | O | Transmit data | PD0 |
| Signal | Dir | Description | IOSet3 |
|---|---|---|---|
| URXD3 | I | Receive data | PB11 |
| UTXD3 | O | Transmit data | PB12 |
uart3: serial@fc008000 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart3_ioset1>;
atmel,use-dma-rx;
atmel,use-dma-tx;
status = "okay";
};
pinctrl@fc038000 {
pinctrl_uart3_ioset1: uart3_ioset1 {
pinmux = <PIN_PC12__URXD3>,
<PIN_PC13__UTXD3>;
bias-disable;
};
pinctrl_uart3_ioset2: uart3_ioset2 {
pinmux = <PIN_PC31__URXD3>,
<PIN_PD0__UTXD3>;
bias-disable;
};
pinctrl_uart3_ioset3: uart2_ioset3 {
pinmux = <PIN_PB11__URXD3>,
<PIN_PB12__UTXD3>;
bias-disable;
};
};
UART4
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| URXD4 | I | Receive data | PB3 |
| UTXD4 | O | Transmit data | PB4 |
uart4: serial@fc00C000 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart4_ioset1>;
status = "okay";
};
pinctrl@fc038000 {
pinctrl_uart4_ioset1: uart4_ioset1 {
pinmux = <PIN_PB3__URXD4>,
<PIN_PB4__UTXD4>;
bias-disable;
};
};
FLEXCOM0
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| FLEXCOM0_IO1 | I | Receive data | PB28 |
| FLEXCOM0_IO0 | O | Transmit data | PB29 |
flx0: flexcom@f8034000 {
atmel,flexcom-mode = <ATMEL_FLEXCOM_MODE_USART>;
status = "okay";
uart5: serial@200 {
compatible = "atmel,at91sam9260-usart";
reg = <0x200 0x200>;
interrupts = <19 IRQ_TYPE_LEVEL_HIGH 7>;
clocks = <&flx0_clk>;
clock-names = "usart";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_flx0_ioset1>;
atmel,fifo-size = <32>;
status = "okay";
};
};
TX and RX lines
pinctrl@fc038000 {
pinctrl_flx0_default: flx0_ioset1 {
pinmux = <PIN_PB28__FLEXCOM0_IO0>, /* TX */
<PIN_PB29__FLEXCOM0_IO1>; /* RX */
bias-disable;
};
};
TX and RX lines plus CTS and RTS
pinctrl@fc038000 {
pinctrl_flx0_default: flx0_ioset1 {
pinmux = <PIN_PB28__FLEXCOM0_IO0>, /* TX */
<PIN_PB29__FLEXCOM0_IO1>, /* RX */
<PIN_PB31__FLEXCOM0_IO3>,
<PIN_PC0__FLEXCOM0_IO4>;
bias-disable;
};
};
FLEXCOM1
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| FLEXCOM1_IO1 | I | Receive data | PA23 |
| FLEXCOM1_IO0 | O | Transmit data | PA24 |
flx1: flexcom@f8038000 {
atmel,flexcom-mode = <ATMEL_FLEXCOM_MODE_USART>;
status = "okay";
uart6: serial@200 {
compatible = "atmel,at91sam9260-usart";
reg = <0x200 0x200>;
interrupts = <20 IRQ_TYPE_LEVEL_HIGH 7>;
clocks = <&flx1_clk>;
clock-names = "usart";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_flx1_ioset1>;
atmel,fifo-size = <32>;
status = "okay";
};
};
pinctrl@fc038000 {
pinctrl_flx1_ioset1: flx1_ioset1 {
pinmux = <PIN_PA24__FLEXCOM1_IO0>,
<PIN_PA23__FLEXCOM1_IO1>;
bias-disable;
};
};
FLEXCOM2
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| FLEXCOM2_IO1 | I | Receive data | PA27 |
| FLEXCOM2_IO0 | O | Transmit data | PA26 |
flx2: flexcom@fc010000 {
atmel,flexcom-mode = <ATMEL_FLEXCOM_MODE_USART>;
status = "okay";
uart7: serial@200 {
compatible = "atmel,at91sam9260-usart";
reg = <0x200 0x200>;
interrupts = <21 IRQ_TYPE_LEVEL_HIGH 7>;
clocks = <&flx2_clk>;
clock-names = "usart";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_flx2_ioset1>;
atmel,fifo-size = <32>;
status = "okay";
};
};
pinctrl@fc038000 {
pinctrl_flx2_ioset1: flx2_ioset1 {
pinmux = <PIN_PD26__FLEXCOM2_IO0>,
<PIN_PD27__FLEXCOM2_IO1>;
bias-disable;
};
};
FLEXCOM3
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| FLEXCOM3_IO1 | I | Receive data | PA13 |
| FLEXCOM3_IO0 | O | Transmit data | PA15 |
flx3: flexcom@fc014000 {
atmel,flexcom-mode = <ATMEL_FLEXCOM_MODE_USART>;
status = "okay";
uart8: serial@200 {
dmas = <0>, <0>;
compatible = "atmel,at91sam9260-usart";
reg = <0x200 0x200>;
interrupts = <22 IRQ_TYPE_LEVEL_HIGH 7>;
clocks = <&flx3_clk>;
clock-names = "usart";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_flx3_ioset1>;
atmel,fifo-size = <32>;
status = "okay";
};
};
pinctrl@fc038000 {
pinctrl_flx3_ioset1: flx3_ioset1 {
pinmux = <PIN_PA15__FLEXCOM3_IO0>,
<PIN_PA13__FLEXCOM3_IO1>;
bias-disable;
};
};
FLEXCOM4
| Signal | Dir | Description | IOSet1 |
|---|---|---|---|
| FLEXCOM4_IO1 | I | Receive data | PC29 |
| FLEXCOM4_IO0 | O | Transmit data | PC28 |
flx4: flexcom@fc018000 {
atmel,flexcom-mode = <ATMEL_FLEXCOM_MODE_USART>;
status = "okay";
uart9: serial@200 {
compatible = "atmel,at91sam9260-usart";
reg = <0x200 0x200>;
interrupts = <23 IRQ_TYPE_LEVEL_HIGH 7>;
clocks = <&flx4_clk>;
clock-names = "usart";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_flx4_ioset1>;
atmel,fifo-size = <32>;
status = "okay";
};
};
pinctrl@fc038000 {
pinctrl_flx4_ioset1: flx4_ioset1 {
pinmux = <PIN_PC28__FLEXCOM4_IO0>,
<PIN_PC29__FLEXCOM4_IO1>;
bias-disable;
};
};
Check the serial devices
ls -al /dev/ttyS*
crw------- 1 root tty 4, 64 Jul 28 10:22 /dev/ttyS0
crw-rw---- 1 root dialout 4, 65 Jul 28 09:10 /dev/ttyS1
crw-rw---- 1 root dialout 4, 66 Jul 28 09:10 /dev/ttyS2
crw-rw---- 1 root dialout 4, 67 Jul 28 09:10 /dev/ttyS3
crw-rw---- 1 root dialout 4, 68 Jul 28 09:10 /dev/ttyS4
crw-rw---- 1 root dialout 4, 69 Jul 28 09:10 /dev/ttyS5
crw-rw---- 1 root dialout 4, 70 Jul 28 09:10 /dev/ttyS6
crw-rw---- 1 root dialout 4, 71 Jul 28 09:10 /dev/ttyS7
crw-rw---- 1 root dialout 4, 72 Jul 28 09:10 /dev/ttyS8
crw-rw---- 1 root dialout 4, 73 Jul 28 09:10 /dev/ttyS9
Install minicon
sudo apt update
sudo apt install -y minicom
To use minicom be shure to don't use the Roadrunner debug port from your PC to avoid strange behaviour. Use a ssh remote session instead
Launch and select for example the port /dev/ttyS1
sudo minicom -s
Select:
then set:
wire together the lines PB27 (TXD0) and PB26 (RXD0) to do an hardware loopback the type some characters on minicom to see if it works
Change the limit on /dev/tty entries
To enable more than 8 serial lines change in:
drivers/tty/serial/atmel_serial.c
the line:
#define ATMEL_MAX_UART 8
in:
#define ATMEL_MAX_UART 10
A ready-to-use device tree source
Links
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