TMC457_1 TRINAMIC [TRINAMIC Motion Control GmbH & Co. KG.], TMC457_1 Datasheet - Page 11

• Manufacturer Part Number: TMC457_1
• Description: S-profile motion controller with PID feedback control and high resolution micro stepping sequencer for stepper motors and piezo motors
• Manufacturer: TRINAMIC [TRINAMIC Motion Control GmbH & Co. KG.]

TMC457 DATASHEET (V. 1.16 / 2009-Nov-25)
11
Due to constraints of practical real word application, the integer part of the PID regulator can be clipped
to a limit named pid_iclip. Without this, the integral part of the PID regulator pid_isum increases with
each time step by pid_i*pid_e as long as the motor does not follow. The actual error can be read out
from register pid_e. The integration over time of the error e is done with a fixed clock frequency of
fPID_INTEGRAL[Hz] = fCLK[Hz] / 128. The time scaling for the deviation with respect to time of the
error is controlled by the register named pid_clk_div.
A stabilization of the target position by programmable hysteresis is integrated to avoid oscillations of
regulation when the actual position is close to the real mechanical position. The PID controller of the
TMC457 is fast – programmable up to approximate 100kHz update rate at fCLK = 16 MHz of the
TMC457 – so that it can be used during motion to stabilized the motion. The parameterization of the
TM
PID controller of the TMC457 occurs in a direct way. Due to this, it is named easyPID
. Nevertheless,
the parameterization of a PID controller might need a detailed knowledge of the application and the
dynamic of the mechanics that is controlled by the PID controller. Additionally, a special control register
allows software interaction for additional feedback control algorithms that can be implemented within
the micro controller used to parameterize the TMC457.
5.5 Step Direction Output Interface
The TMC457 is equipped with step direction outputs (STEP, OUT). In Addition, it is equipped with a so
called X_STEP output. A pulse on this output represents a number of (micro) steps. It is configured by
the register named pulse_xstep_div. The TMC457 is able to generate step pulses with up to its clock
frequency fCLK[Hz]. Because a step frequency in the range of the clock frequency of the TMC457
might be too high for usual step direction drivers, an additional step output named X_STEP (extended
step) is available. The X_STEP represents a number of steps to be done at a lower frequency. The
threshold that selects between step pulses and extended step pulses is programmable. This can be
parameterized to give full steps on the XSTEP output of the TMC457.
5.6 Step Direction Input Interface for multi axis interpolation
The TMC457 is equipped with step direction inputs (STEP_IN, DIR_IN). This allows using the TMC457
with an external ramp generator. A number of TMC457 can be synchronized by interconnecting the
step direction inputs and outputs via a switch matrix. One TMC457 is used as master and its step and
direction output is fed to the other TMC457. They can be programmed to follow the master pulses
scaled by the 15 bit factor sd_scale (and sign). This way, multi-axis interpolation can be realized. The
slave motion thus always is equal or slower than the master. When programming the master axis, the
maximum allowed acceleration and velocity values of the slave axis have to be considered.
The step input is sampled once per system clock. Thus, the maximum input frequency is equal to the
half system clock frequency. Please remark, that this also limits the master velocity during interpolated
moves.
5.7 Reference Switch and Stop Switch Interface
The TMC457 is equipped with reference switch that can be programmed for automatic actions. For
details please refer to the register mapping section 6 Register Mapping, page 14 ff. The reference
switch inputs are available to store a position on a reference switch event. Additionally, these inputs
can be enabled to force a stop.
5.8 Micro Step Sequencer
The micro step sequencer can be programmed for different micro step resolutions. The sequencer
controls the mixed decay feature of TRINAMIC stepper motor drivers. Current scaling is also done
TM
under control of the sequencer. When using TMC246 or TMC249 the StallGuard
threshold is under
control of the sequencer. A readable register holds the TRINAMIC stepper motor driver status bits and
diagnosis bits.
TM
5.8.1
ChopSync
CHOPCLK
TM
CHOPCLK
To use the ChopSync
feature together with a TRINAMIC stepper motor driver the output
of the TMC457 has to be connected to the PWM oscillator input OSC of the TRINAMIC
(TMC236, TMC239, TMC246, or TMC249) – without a capacitor at the OSC
stepper motor driver
input. The recommended chopper frequency fOSC for the TRINAMIC stepper motor driver is 36kHz.
The chopper frequency should not be below 25kHz and must be lower than 50kHz. The chopper
frequency is programmed via the register chop_clk_div.
Copyright © 2009 TRINAMIC Motion Control GmbH & Co. KG