Communication with multiple uart interface

banada · August 3, 2022, 4:54pm

Hello i have a BPI-R2 when i typed dmesg | grep tty i saw there is 4 serial interface calles ttyS0,ttyS1,ttyS2,ttyS3 i want to use all of them but i do not know how can i acces gpio pins of these interfaces. Could you help me ? Best regards I send request for schematic but i did not get any response now. If you have could you share with me

dangowrt · August 3, 2022, 5:03pm

Schematics for R2 are public, find them here: https://wiki.banana-pi.org/Banana_Pi_BPI-R2#Documents

I think there are only 3 usable UARTs on the R2, and one of them is usually used as debugging console. The other two can be found on the 40-pin GPIO header:

frank-w · August 3, 2022, 6:03pm

Afair there was a 4th with only solder pads but i don’t remember where it was as it was not easy usable and i did not need 4

dangowrt · August 3, 2022, 6:09pm

Afair the CTS/DTS signals of the debugging UART are pads next to the 3-pin header. According to pinctrl UART3 RX/TX is on pins 242, 243 which is shared with UART2 RTS/CTS which is the debugging UART. So by switching pinctrl to use those pins as UART you may gain a 4th UART on those pads.

frank-w · August 3, 2022, 6:12pm

Ah,right,wasn’t sure it were the pads near debug-uart,but this was already in my mind. That requires maybe a similar patch line we did on r3 for the uarts (splitting pins into rx/tx and cts/rts).

banada · August 8, 2022, 1:55pm

How can i use pinctrl , I am new at embedded linux. could you share a example document on banana pi ? Best regards

banada · August 8, 2022, 2:29pm

Can I change pin of ttyS3 to GPIO pin by software ?

frank-w · August 8, 2022, 3:37pm

Uart3 is already defined and if found by system it should work.

github.com

frank-w/BPI-R2-4.14/blob/4.14-main/arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts#L948


	pinctrl-0 = <&uart1_pins_a>;
	status = "okay";
};


&uart2 {
	status = "okay";
};


&uart3 {
	pinctrl-names = "default";
	pinctrl-0 = <&uart3_pins_a>;
	status = "okay";
};


&usb1 {
	vusb33-supply = <&reg_3p3v>;
	vbus-supply = <&reg_5v>;
	status = "okay";
};


&usb2 {

github.com

frank-w/BPI-R2-4.14/blob/4.14-main/arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts#L604




	uart1_pins_a: uart@1 {
		pins_dat {
			pinmux = <MT7623_PIN_81_URXD1_FUNC_URXD1>,
				 <MT7623_PIN_82_UTXD1_FUNC_UTXD1>;
		};
	};


	uart3_pins_a: uart@3 {
		pins_dat {
			pinmux = <MT7623_PIN_243_UCTS2_FUNC_URXD3>,
				 <MT7623_PIN_242_URTS2_FUNC_UTXD3>;
		};
	};


	consys_pins_default: consys_pins_default {
		adie {
			pinmux = <MT7623_PIN_60_WB_RSTB_FUNC_WB_RSTB>,
				<MT7623_PIN_61_GPIO61_FUNC_TEST_FD>,
				<MT7623_PIN_62_GPIO62_FUNC_TEST_FC>,
				<MT7623_PIN_63_WB_SCLK_FUNC_WB_SCLK>,

Uart2 has no own pinctrl defined there…maybe it uses some defaults in driver or inherits settings from uboot

banada · August 11, 2022, 2:04pm

Hello I want to move my project from BPI-R2 to BPI R2 PRO according to this page(https://wiki.banana-pi.org/BPI-R2_Pro_all_GPIO_PIN_define) there is 4 uart pins ? Is there any problem about using the four uart of bpi-r2 pro ? Best regards

frank-w · August 11, 2022, 3:55pm

You have uart 0,5,7 and 9 on gpio-header, for uart9 you have to disable spi3+pwm12+pwm13 in bpi-r2pro.dts

github.com

frank-w/BPI-R2-4.14/blob/5.19-r2pro-pcie-new/arch/arm64/boot/dts/rockchip/rk3568-bpi-r2-pro.dts#L753


	pinctrl-0 = <&spi3m1_pins>;
	status = "disabled";
};


&tsadc {
	rockchip,hw-tshut-mode = <1>;
	rockchip,hw-tshut-polarity = <0>;
	status = "okay";
};


&uart0 {
	/* pin 8 (TX) + 10 (RX) (RTS:16, CTS:18) of header con2 */
	status = "disabled";
};


&uart2 {
	/* debug-uart */
	status = "okay";
};


&uart7 {

Btw. The official page states Debug-uart is uart0 (@sinovoip pls fix) ,but schematic (and my tests/dts) says uart2.

Note that bpi-r2-pro is completely different to bpi-r2. Different soc, different bootchain and uboot config, mainline uboot currently broken (2022-04 usable from my repo), wan=eth0,lan-ports=eth1, dsa driver mainline,but needs a patch to get ~1Gbit (not 2.5gbit like r2). Pcie not yet mainline