TMC428 ETC-unknow, TMC428 Datasheet - Page 7

• Manufacturer Part Number: TMC428
• Description: Intelligent Triple Stepper Motor Controller With Serial Peripheral Interfaces
• Manufacturer: ETC-unknow

TMC428 DATA SHEET (V. 1.00 / February 12, 2001)
Functional Description and Block Diagram
From the user’s point of view, the TMC428 consists of a set of registers of different units and on-chip
RAM (see. Figure 4), accessed via the serial µC interface in an uniform way. The serial interface to the
micro controller is easy to use. It uses just a simple protocol with fixed length datagrams for read and write
access. The serial interface to the stepper motor driver chain has to be configured by an initialization
sequence which writes the configuration into the on-chip RAM. Once configured the serial driver interface
works autonomously. The internal multiple port RAM controller of the TMC428 autonomously takes care
of access scheduling. So, the user may read and write both, registers and on-chip RAM at any time. The
registers hold global configuration parameters and the motion parameters. The on-chip RAM stores the
configuration of the serial driver interface and the micro step table.
The ramp generator monitors the motion parameters stored in its registers. If required, it generates step
pulses automatically taking user defined motion parameter limits into account. The serial driver interface
automatically sends datagrams to the stepper motor driver chain on demand. The ramp generator
calculates velocity profiles controlling the pulse generator. The micro step unit (including sequencer)
processes step pulses from the pulse generator– representing micro steps, half steps, or full steps
depending on the selected step resolution –and makes the results available to the serial driver interface.
The ramp generator also interfaces the reference switch inputs. Unused reference switches have to be
connected to ground. A pull-down resistor is necessary at the SDI_S input of the TMC428 for those serial
peripheral interface stepper motor drivers that set their serial data output to high impedance ‘Z’ while
inactive.
The interrupt controller continuously watches reference switches and ramp generator conditions and
generates an interrupt if required. To save pins, the interrupt signal is multiplexed to the SDO_C signal.
This signal becomes the low active interrupt signal called nINT while nSCS_C is high (see Figure 5). So, if
the micro controller disables the interrupt during access to the TMC428 and enables the interrupt
otherwise, the multiplexed interrupt output of the TMC428 behaves like a dedicated interrupt output. For
polling, the TMC428 sends the status of the interrupt signal to the micro controller with each datagram.
To drive a stepper motor to a new target position, the user just overwrites the target position of that
stepper motor by sending a datagram to the TMC428. To run a stepper motor with a target velocity, the
user just writes it into a register assigned to a stepper motor.
Figure 4: TMC428 functional block diagram
Copyright © 2000, TRINAMIC Microchips GmbH
TRINAMIC
M I C R O C H I P S
nSCS_C
SDO_C
SCK_C
SDI_C
TEST
CLK
serial µC interface
controller
interrupt
pulse generator
ramp generator
&
micro step unit
sequencer )
( including
power-on
reset
ported RAM
multiple
serial driver interface
regulator
voltage
GND
V5
V33
470nF
[nSCS2]
[nSCS3]
nSCS_S
10K
SCK_S
SDO_S
SDI_S
7
7