datasheet for TMC454 by Trinamic

TMC454 DATASHEET (v. 1.02 / October 5, 2009) 17

4.5 Using TRINAMIC Driver (TMC236, TMC239, TMC246, TMC249) via SPI

Hint:

TMCDRV_SDI is an output and has to be connected with the pin named SDI of the

TRINAMIC driver (TMC236, TMC239, TMC246, TMC249). TMCDRV_SDO is an input and has to be connected with the output pin named SDO of the TRINAMIC driver.

Please refer the TRINAMIC stepper motor driver datasheets for a detailed description of the control signals resp. control bits.

4.5.1 Control Signals

There are two control signals for the TRINAMIC drivers.

4.5.1.1 TMCDRV_MD_EN

The signal named TMCDRV_MD_EN controls the Mixed Decay Feature of the TRINAMIC stepper motor drivers TMC236, TMC239, TMC246, TMC249.

4.5.1.2 TMCDRV_SHAFT

The shaft signal is intended to be used for changing the direction of revolution of a stepper motor. The shaft signal is not intended to be used as a direction signal. It is intended to be used for compatibility with existing applications based on the TMC453 with an other driver configuration.

4.5.2 Diagnosis Signals

There are three diagnosis signals directly available.

4.5.2.1 TMCDRV_OTPW

The TMCDRV_OTPW is the “over Temperature Pre-Warning” signal sent back from the TRINAMIC driver via

SPI.

4.5.2.2 TMCDRV_ERROR

The TMCDRV_ERROR is the logical of error condition signals (short, open load, over temperature)

4.5.3 Using StallGuard

TM with TMC246 or TMC249

The TMC454 is equipped with a low active StallGuard

TM

output named TMCDRV_nSTALL. The output is low active to used it to drive directly TMC454 reference switch inputs. The StallGuard

TM

threshold is set by the three LSB of the DAC2. These three LSB are mapped internally to the TRINAMIC stepper motor SPI interface.

With this, the DAC2 can still be used for analog current scaling.

4.5.4 PWM DAC for Current Scaling

Analog current scaling can be done by using DAC2 without an additional external DAC. A simple resistor voltage divider with a capacitor driven by the PWM_DAC2 output of the TMC454. The internal resistance of the both INA and INB analog control inputs of the TRINAMIC stepper motor drivers have to be taken into account.

Please refer to the TMC236 / TMC239 / TMC246 / TMC249 data sheets for details.

The PWM clock frequency fPWM is fCLKIN / 256. So, for a clock frequency fCLKIN = 16 MHz one gets a

PWM frequency fPWM = 16 MHz / 256 = 62.5 kHz for the PWM_DAC2 output.

Max Units Parameter Description fUPDT_TMC

number of TMC454 clock cycles for TRINAMIC stepper motor driver data update, the drivers data are updated with a frequency of fCLKIN[Hz] / 52

fUPDT_TMC_8

update frequency at 8 MHz clock frequency of TMC454

fUPDT_TMC_16 update frequency at 16 MHz clock frequency of TMC454

52

154

308 clock cycles kHz kHz

Table 4.5 : Update Frequency of TRINAMIC Drivers

Copyright © 2009, TRINAMIC Motion Control GmbH & Co. KG