Once a short condition is safely detected the corresponding (Page 60 / 76) TMC2225 Power Driver for Stepper Motors Integrated Circuits Datasheet Rev1.15

TMC2225 DATASHEET (Rev. 1.15 / 2023-FEB-16)

Once a short condition is safely detected, the corresponding driver bridge (A or B) becomes switched

off, and the s2ga or s2gb flag, respectively s2vsa or s2vsb becomes set. In order to restart the motor,

disable and re-enable the driver. Note, that short protection cannot protect the system and the power

stages for all possible short events, as a short event is rather undefined and a complex network of

external components may be involved. Therefore, short circuits should basically be avoided.

13.3 Open Load Diagnostics

UART

Interrupted cables are a common cause for systems failing, e.g., when connectors are not firmly

plugged. The TMC2225 detects open load conditions by checking if it can reach the desired motor coil

current. This way, also undervoltage conditions, high motor velocity settings or short and

overtemperature conditions may cause triggering of the open load flag, and inform the user, that

motor torque may suffer. In motor stand still, open load cannot always be measured, as the coils

might eventually have zero current.

Open load detection is provided for system debugging.

To safely detect an interrupted coil connection, operate in SpreadCyle, and check the open load flags

following a motion of minimum four times the selected microstep resolution into a single direction

using low or nominal motor velocity operation, only. However, the ola and olb flags have just

informative character and do not cause any action of the driver.

13.4 Diagnostic Output

The diagnostic output DIAG and the index output INDEX provide important status information . An

active DIAG output shows that the driver cannot work normally. The INDEX output signals the

microstep counter zero position, to allow referencing (homing) a drive to a certain current pattern.

The function set of the INDEX output can be modified by UART. Figure 13.1 shows the available

signals and control bits.

DIAG

TMC220x, only

drv_err

Power-on reset

Charge pump undervoltage (uv_cp)

Overtemperature (ot)

Short circuit (s2vs, s2g) over temperature (ot)

Power stage disable (e.g. pin ENN)

INDEX

Figure 13.1 DIAG and INDEX outputs

Index pulse

Overtemperature prewarning (otpw)

Toggle upon each step

GCONF.index_otpw

GCONF.index_step