How to connect a BTT-MOT-EXP to an SKR v2.0

Overview

BigTreeTech released the BTT-MOT-EXP. It is an adapter that would ordinarily allow 3 more extra drivers to be added to an SKR v2.0.

Connecting the boards

Connect two 10-pin IDC cables between EXP1 and EXP2 on the SKR v2.0 and EXP1 and EXP2 on the BTT EXP-MOT V1.0.
12/24v power should be connected to the BTT-MOT-EXP to power the drivers.
If using the drivers in UART mode, a jumper should be added to the pins underneath the driver as normal.

SKR v2.0 Board.txt configuration

Please edit the stepper.numSmartDrivers in the board.txt file to 8 (assuming you have TMC2208, TMC2009, TMC2225, TMC2226 or TMC5160 drivers in all other sockets).

stepper.numSmartDrivers = 8

Please add the following lines to the board.txt.

stepper.enablePins = { E.3, D.6, D.1, C.7, D.13, C.4, E.13, E.12 }
stepper.stepPins = { E.2, D.5, A.15, D.15, D.11, A.7, E.7, A.6 }
stepper.directionPins = { E.1, D.4, A.8, D.14, D.10, B.2, A.4, A.5 }
stepper.TmcUartPins = { E.0, D.3, D.0, C.6, D.12, E.11, B.9, B.0 }

Sensorless Homing

Supported by only the TMC2209, TMC2226 and TMC5160 If using sensorless homing/stall detection on the BTT-MOT-EXP with TMC2209 or TMC2226 the following line must be added to the board.txt file. It is not needed with TMC5160.

stepper.TmcDiagPins = { C.1, C.3, C.0, C.2, A.0, E.10, B.1, C.5 }

Please only include the diag pin numbers where you intend to use sensorless homing on that axis.
For example, if you only intend to use sensorless homing/stall detection on driver 0 and driver 1, only include F.2 and C.13 in your board.txt file.
For more information about setting up sensorless homing, please read this.

Config.g Modification

The three added drivers would become driver 5, driver 6 and driver 7.
e.g.

M569 P5 S0
M569 P6 S0
M569 P7 S0
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