TD-W8970 adding i2c RTC (PCF8563)

Hardware Questions and Recommendations
1

As title I've some PCF8563 RTC board, I'd like to use them on my TD-W8970. I already saw that it's compatible (found it somewhere looking around with openwrt source and make menuconfig).

I've a small problem... where do I solder this? i can't find any pin for i2c.

2

If there are no dedicated I2C pins then simply bitbang them on any 2 GPIOs.
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/Documentation/devicetree/bindings/i2c/i2c-gpio.txt?h=v4.14.69

I have couple of examples for both legacy mach files and current DTS

3

I can't find GPIO pins, also in the wiki page there is no GPIO pins listed. Could they be on the back of the PCB? If I take somr HQ photo, may someone help me to find i2c pins or GPIO?

4

Sorry to resurrect this old thread... btw I found that usb leds on the back are driven by GPIO pins 19 and 20, by looking at TDW89X0.dtsi (shared between TDW8970.dts and TDW8980.dts)

        gpio-leds {
                ...
                usb0: usb0 {
                        label = "tdw89x0:green:usb";
                        gpios = <&gpio 19 GPIO_ACTIVE_HIGH>;
                };
                usb2: usb2 {
                        label = "tdw89x0:green:usb2";
                        gpios = <&gpio 20 GPIO_ACTIVE_HIGH>;
                };
                ...

I'm doing some nice mods on this router and this other mod will be perfect:

  • Small fan on top. DONE. Max temp went from 75 to 35 °C. Hooked to power button.
  • "Internal disk" USB. Removed both USB ports. Bought a female USB port and a mini 2GB USB drive. There is an empty place where I'll put(/glue) my internal port). WAITING THE MAIL

Should it make sense to remove the USB leds (never used them anyway), and use their pin to connect the RTC?