TMC424 Datasheet – (V1.04 / 2015-JUL-01)

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Copyright © 2011 TRINAMIC Motion Control GmbH & Co. KG

8 SPI-Protocol for Interface with 6-bit Register

The 6-bit SPI Interface is used to receive step / direction information from the TMC429. The TMC424

processes the data and issues the corresponding step / direction signals via the step / direction pins.

Bit0 (Pulse 1) have to be sent first to the TMC424.

Bit

Step / Direction Converter

0

Pulse 1

1

Direction 1

2

Pulse 2

3

Direction 2

4

Pulse 3

5

Direction 3

Table 11: SPI Datagram Step / Direction Converter

The order of the control signals serially sent from the TMC429 has to be defined. This can be done by

writing so called primary signal codes into the stepper motor driver datagram configuration area of

the on-chip configuration RAM of the TMC429. This signals codes are $13 (step first) and $12

(direction). To switch to the next motor the next motor bit (NxM) has to be set.

Position within

datagram

Driver/motor

NxM bit

TMC429 signal

code

RAM data

TMC429

mnemonic of

primary signal

0

1

0

$13

$13

Step

1

1

$12

$32

Direction

2

2

0

$13

$13

Step

3

1

$12

$32

Direction

4

3

0

$13

$13

Step

5

1

$12

$32

Direction

Table 12: Datagram example and RAM contents for three step-direction drivers

8.1 Step and Direction Pulse conversion

Step pulses can be modified in their pulse width and delayed after an direction change was done. The

corresponding datagram (See 7.3) on page 17) is used to parameterize the Step / Dir interface.

t

t

step_in

dir

step pulse length

step pulse delay

t

step_out

Figure 12: Step Direction conversion