User Manual

TMCM-351 Hardware Manual (V1.06 / 2011-NOV-14) 22

6.1.2 EEPROM

To store TMCL™ programs for stand-alone operation the TMCM-351 module is equipped with a 16kByte

EEPROM attached to the microcontroller. The EEPROM can store TMCL™ programs consisting of up to 2048

TMCL™ commands. The EEPROM is also used to store configuration data.

6.1.3 TMC428 motion controller

The TMC428 is a high-performance stepper motor control IC and can control up to three 2-phase-stepper-

motors. Motion parameters like speed or acceleration are sent to the TMC428 via SPI by the microcontroller.

Calculation of ramps and speed profiles are done internally by hardware based on the target motion

parameters.

6.1.4 Stepper motor drivers

On the TMCM-351 modules the TMCM249 chips are used. These chips have the stallGuard™ feature.

As the power dissipation of TMC249 chips is very low no heat sink or cooling fan is needed. The

temperature of the chips does not get high. The coils will be switched off automatically when the

temperature or the current exceeds the limits and automatically switched on again when the values are

within the limits again.

The TMCM-351 module is equipped with a circuit that extends the microstep resolution of the TMC249 chips

to true 64 times microstepping. The maximum peak coil current of each stepper motor driver chip is

1500mA.

6.2 stallGuard™ - sensorless motor stall detection

The TMCM-343 modules are equipped with the stallGuard™ feature. The stallGuard™ feature makes it

possible to detect if the mechanical load on a stepper motor is too high or if the traveler has been

obstructed. The load value can be read using a TMCL™ command or the module can be programmed so that

the motor will be stopped automatically when it has been obstructed or the load has been too high.

stallGuard™ can also be used for finding the reference position without the need for a reference switch:

Activate stallGuard™ and then let the traveler run against a mechanical obstacle that is placed at the end of

the way. When the motor has stopped it is definitely at the end of its way, and this point can be used as

the reference position.

For using stallGuard™ in an actual application, some manual tests should be done first, because the

stallGuard™ level depends upon the motor velocities and on the occurrence of resonances.

Mixed decay should be switched off while stallGuard™ is in use in order to get usable results.

Value

Description

stallGuard™ function is deactivated (default)

1… 7

Motor stops when stallGuard™ value is reached and position is not set zero.

Table 6.1: stallGuard™ parameter SAP 205

To activate the stallGuard™ feature use the TMCL™ command SAP 205 and set the stallGuard™ threshold

value according to Table 6.1. The actual load value is given by GAP 206. The TMCL-IDE has some tools which

let you try out and adjust the stallGuard™ function in an easy way. They can be found at stallGuard™ in the

Setup menu and are described in the following chapters. Please refer to the TMCM-341/342/343 TMCL™

Firmware Manual for further information about working with TMCL-IDE.