Connecting an SKR Pro v1.2 via an ESP32 WiFi Adapter

Homemade ESP32

Use an ESP32 with USB programming as it already 5v tolerant and it allows for updating via USB. They also need to be the 36 pin variety so they have GPIO0 broken out.

BOM

• 1 x 36 pin ESP32
• 1 x 330R resistor
• jumpers or other ways of connecting to the SKR Pro v1.2

Preparing the ESP32

Follow the instructions here.
Alternatively you can connect the RX/TX pins on the ESP32 to a set of RX/TX pins on the SKR Pro v1.2.

Connecting the ESP32

The pinout for the SKR Pro v1.2 can be found here and the schematic for the Duet 2 WiFi for reference can be found here.

The table below shows the pins required on the ESP32 and what they are connected to on the SKR Pro v1.2. Please ensure that your cables are no longer than 30cm although they should ideally be as short as possible.

Manual board.txt Changes

If you are using a set of config files provided by someone else or have no need to use the configurator, you will need to create your board.txt file manually.

Below are the contents that should be used.

//Config for SKR Pro v1.2
board = biquskrpro_1.1
//WiFi pins
8266wifi.espDataReadyPin = PG_10
8266wifi.TfrReadyPin = PF_11
8266wifi.espResetPin = PF_12


//ESP32 RX/TX Settings
8266wifi.serialRxTxPins = { PD_9, PD_8 }
serial.aux.rxTxPins = { PA_10, PA_9 }
heat.tempSensePins = { PF_6, PF_3, PF_4, PF_5 }

If the WiFi adapter is not working correctly e.g. error: “Failed to attach interrupt to pin G.10” after restarting the module (M552 S-1; M552 S0) check that the interrupt is not already used e.g. with “e1stop”. See also here.

The SKR Pro also uses a different pin for the CS for SPI so you need to modify stepper.TmcUartPins in board.txt accordingly.

For example, if you had TMC5160s on X and Y, you would add the following line to your board.txt

stepper.TmcUartPins = { PA_15, PB_8, PE_1, PD_4, PD_1, PD_6, PF_11, PG_10, NoPin, NoPin, NoPin }

Note the added two SPI pins for the TMC5160s and then the remainder of the pins are the UART pins used by TMC22XX drivers.

Smart Drivers

If using TMC5160 or TMC22XX drivers (where 22XX is either the TMC2208, TMC2209, TMC2225 or TMC2226), the following line must also be added to the board.txt file

stepper.numSmartDrivers = X

Where X is the number of drivers fitted in total.

TMC5160 SPI Drivers

If using TMC5160 drivers, the following lines must also be added to the board.txt file.

stepper.num5160Drivers = X
stepper.spiChannel = 2

Where X is the number of TMC5160 drivers fitted.

The drivers must be grouped together with the installed TMC5160s first. They can have gaps between each driver and/or driver type. So, if you have say 3 TMC5160s and 1 TMC22XX and 1 other driver, the 5160s should installed first (e.g. in slots 0, 1 and 2 or slots 0, 3 and 4), the TMC22XX in a slot after the 5160 and the remaining driver last. You can use RRF to assign any of those slots to an axis/extruder.

Sensorless Homing

Follow the instructions as found here

Manual board.txt Changes

If you are using a set of config files provided by someone else or have no need to use the configurator, you will need to create your board.txt file manually.

Below are the contents that should be used.

//Config for SKR Pro v1.2
board = biquskrpro_1.1
//WiFi pins
8266wifi.espDataReadyPin = PG_10
8266wifi.TfrReadyPin = PF_11
8266wifi.espResetPin = PF_12


//ESP32 RX/TX Settings
8266wifi.serialRxTxPins = { PD_9, PD_8 }
serial.aux.rxTxPins = { PA_10, PA_9 }
heat.tempSensePins = { PF_6, PF_3, PF_4, PF_5 }

If the WiFi adapter is not working correctly e.g. error: “Failed to attach interrupt to pin G.10” after restarting the module (M552 S-1; M552 S0) check that the interrupt is not already used e.g. with “e1stop”. See also here.

The SKR Pro also uses a different pin for the CS for SPI so you need to modify stepper.TmcUartPins in board.txt accordingly.

For example, if you had TMC5160s on X and Y, you would add the following line to your board.txt

stepper.TmcUartPins = { PA_15, PB_8, PE_1, PD_4, PD_1, PD_6, PF_11, PG_10, NoPin, NoPin, NoPin }

Note the added two SPI pins for the TMC5160s and then the remainder of the pins are the UART pins used by TMC22XX drivers.

Drivers

Although the original method of having the firmware detect the drivers is still supported, as we have now added TMC2240 support, there is now a new method.
The following line should be added (obviously with the array entries matching your drivers and their locations):

stepper.numSmartDrivers = X
stepper.DriverType = {Tmc2208, Tmc2240, tmc2209, tmc5160, stepdir}

For the number of smart drivers, if you have the following installed (tmc2209, none, tm5160, stepdir, tmc2209) then numSmartDrivers needs to be set to 5 not to 3. Basically it means how many entries there are in the driver types array. Entries after that number get set to stepdir.

The DriverType array allows for any driver to be used in any slot so there is no order requirement like the previous detection method. The array must also include an entry for each driver slot up to the last one thats populated.
The following list of entries are valid:

none
stepdir
tmc2208
tmc2209
tmc2660
tmc5160
tmc2240

If using TMC2240 or TMC5160 drivers, you also need to add the correct spi channel:

stepper.spiChannel = 2

TMC2240 Driver Temperature

TMC2240 drivers support reporting their own temperature, rather than just hot and very hot like the other TMC drivers. To utilise this, add the following line to your config.g

M308 S11 Y"drivers"

This will return the highest temperature reading from any of the drivers, 2240s will return the actual temperature, other drivers will return 0, 100 or 150 (as before).

If you want to know the temperature of a particular driver you need to add the following line (as well as the above):

M308 S12 Y"drivertemp" p"S11.X"

Where x is the driver number that matches the driver number used by M569

Sensorless Homing

Follow the instructions as found here