TMC424-PI24 Trinamic Microchips, TMC424-PI24 Datasheet - Page 9

• 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)
microcontroller to the TMC428 is idle, the low active serial chip select input nSCS_C and also the serial
data clock signal SCK_C are set to high. While the signal nSCS_C is high, the TMC428 assigns the
status of the internal low active interrupt signal named nINT to the serial data output SDO_C (see
Figure 6-1). The serial data input SDI_C of the TMC428 has to be driven by the microcontroller.
Important Hint: In contrast to most other SPI
is always driven. So, it will never be high impedance ‘Z’.
The signal nSCS_C has to be high for at least three clock cycles before starting a datagram
transmission. To initiate a transmission, the signal nSCS_C has to be set to low. Three clock cycles
later the serial data clock may go low. The most significant bit (MSB) of a 32 bit wide datagram comes
first and the least significant bit (LSB) is transmitted as the last one. A data transmission is finished by
setting nSCS_C high three or more CLK cycles after the last rising SCK_C slope. So, nSCS_C and
SCK_C change in opposite order from low to high at the end of a data transmission as these signals
change from high to low at the beginning. The timing of the serial microcontroller interface is outlined in
Figure 6-1.
6.2 Automatic Power-On Reset
The TMC428 performs an automatic power-on reset. For details see section Power-On-Reset, page
48. The TMC428 cannot be accessed before the power-on-reset is completed and the clock is stable.
All register bits are initialized with ‘0’ during power on reset, except the SPI clock pre-divider clk2_div
(see section 9.7, page 28) that is initialized with 15.
6.3 Serial Peripheral Interface to Stepper Motor Driver Chain
The timing of the serial stepper motor interface is similar to that of the microcontroller interface. It
directly connects to SPI
individually for each stepper motor driver chip of the daisy chain. It is simply configurable by sending a
fixed sequence of datagrams to the TMC428 to initialize it after power-up. Once initialized, the TMC428
autonomously generates the datagrams for the stepper motor driver daisy chain without any additional
interventions of the microcontroller.
Figure 6-2: Timing diagram of the serial stepper motor driver interface
Copyright © 2000–2003 TRINAMIC Microchips GmbH
A complete serial datagram frame has a fixed length of 32 bit. While the data transmission from the
nSCS_S
SDO_S
SCK_S
SDI_S
CLK
tCLK
tSUSCSdrv
tPD
tHDSCSdrv
TM
smart power stepper motor drivers. The SPI
tPD
tCKSL
1 x sampled SDI_S
sdo_s_bit#0
sdi_s_bit#0
tPD
tCKSH
one full stepper motor driver datagram
TM
sdi_s_bit#1
compatible devices, the SDO_C signal of the TMC428
sdo_s_bit#1
tDATAGRAMdrv
m x sampled SDI_S
m datagram bits
sdo_s_bit#n-1
sdi_s_bit#n-1
TM
1 x sampled SDI_S
sdi_s_bit#n
sdo_s_bit#n
datagram is configurable
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