[r64] how should I use the rtc function on the r64, and if there are two uarts in the 40pinGPIO of the r64, and how to enable them

Banana Pi BPI-R4/BPI-R3 Mini/BPI-R3/BPI-R64/BPI-R2 Linux
1

I want to know, how should I use the rtc function on the r64, and if there are two uarts in the 40pinGPIO of the r64, and how to enable them.

2

Afaik r64 has no rtc function…at least not with battery buffer so time in rtc survives reboot/poweroff. But you can connect external rtc via i2c,spi or uart to the gpio header and use this.

For uart they can be enabled in dts but look if there are additional functions on same pins that may block the uart.

https://wiki.fw-web.de/doku.php?id=en:bpi-r64:gpio

E.g. for uart1 there is pwm1/2 on same pins,so you have to disable these for using uart1. I’m not sure if the pwms can be simply disabled alone as afair r64 uses 1 controller for all pwm.

3

I tried for a day, but I only found one uart on 40pin, and I found an interesting thing, when I use gpio (51/52), I can’t use gpio (59/60), when I use gpio ( 59/60), I can’t use the gpio (51/52); It seems that only one of them can be used:思维:

4

Also, when I want to use USB to TTL, it doesn’t show up, but I’m sure the USB interface is available:thinking:

5

51/52 are looking to be same uart like 59/60: rxd2+txd2,but last with rts/cts 61/62. These blocking rxd4/txd4,so use 51/52 as uart2. Uart4 as 61/62, 57/58 as uart3 (pin 27/28). 55/56 as uart1 (pins 3,5)

But you will need to enable these uarts and disable other functions)

Usb-adapter will need drivef added to kernel