https://github.com/MarlinFirmware/Marlin/issues/15754#issuecomment-552363829

**possible pins for i2c on btt skr 1.3 :**

P0.0 SDA1 is used for E1DIR
P0.1 SCL1 is used for E1STP
P0.10 SDA2 is used for E1EN
P0.11 SCL2 is used for E0DIR
P0.19 SDA1 is used for YSTP
P0.20 SCL1 is used for YDIR
P0.27 SDA0 is used for SD card Data
P0.28 SCL0 is used on pin 9 of EXP1 (ie LCD connector)

**Changes:**

E1STEP originally on P0_00 now on P1_08 (E0-RX)
E1DIR  originally on P0_01 now on P1_01 (E1-RX)

changes made in : 
- Marlin/src/pins/lpc1768/pins_BTT_SKR_common.h
- Marlin/src/pins/lpc1768/pins_BTT_SKR_V1_3.h