TMC424-PI24 Trinamic Microchips, TMC424-PI24 Datasheet - Page 30

• Manufacturer Part Number: TMC424-PI24
• Description: Economic Miniature Three Axis Microstepping Stepper Motor Controller
• Manufacturer: Trinamic Microchips

TMC428 DATASHEET (V. 2.00 / November 12, 2003)
So, for a chain of three drivers with 12 bit datagram length each, the upper limit of the datagram
frequency is f_datagram[Hz] = f_sck_s[Hz] / ( 1 + 3*(12+1) + 1) = f_sck_s[Hz] / 41.
The TMC428 sends datagrams to the stepper motor driver chain on demand only. No datagrams are
send if continuous_update is ‘0’ during rest periods. This reduces the communication traffic. The
multiplexed reference switch inputs are processed while datagrams are sent to the stepper motor
driver chain only. If reference switches are configured to stop associated stepper motors automatically,
the configuration bit continuous_update must be set to ‘1’ to force periodic sending of datagrams to
the stepper motor driver chain and to sample the reference switches periodically, if all stepper motors
are at rest. With this, a stepper motor restarts if its associated reference switch becomes inactive.
Without continuous update, a stepper motor stopped by a reference switch would stay at rest until a
datagram is sent to the stepper motor driver chain, if its reference switch is inactive. Then, the relevant
stepper motor can be moved into the direction opposite to the reference switch or it can be moved in
both directions by disabling the automatic stop function. The continuous update datagram frequency is
f_clk[Hz]
ramp_div_1, ramp_div_2 are the ramp_div parameters of the stepper motors.
The bit continuous_update is also important for the automatic coil current scaling (see page 17). This
bit must be set to ‘1’ to be sure that the coil current is also scaled if all motors are at rest.
Figure 9-3: Reference switch configuration ‘left-side-only’ for mot1r=0 (and refmux=0)
Figure 9-4: Reference switch configuration ‘two-one-null’ for mot1r=1 (and refmux=0)
Copyright © 2000–2003 TRINAMIC Microchips GmbH
nSCS_C
SDI_C
SCK_C
SDO_C
nSCS_C
SDI_C
SCK_C
SDO_C
CLK
CLK
REF1
REF1
V33
V33
TMC428
/
TMC428
REF2
REF2
32768
V5
V5
REF3
TEST
TEST
REF3
GND
*
GND
nSCS_S
SDO_S
SCK_S
nSCS_S
(2^ramp_div_0+2^ramp_div_1+
SDI_S
SDO_S
SCK_S
SDI_S
no reference switch for stepper motor 3
+VCC
+VCC
+VCC
+VCC
+VCC
+VCC
2^ramp_div_2)
where
ramp_div_0,
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