TMC4361A Datasheet, PDF (108/229 Pages) TRINAMIC Motion Control GmbH & Co. KG. – SPI Interfaces for SPI motor stepper drivers.

TMC4361A Datasheet | Document Revision 1.20 • 2016-NOV-10
108/229
Sending Cover
Datagrams to
TMC26x
Based on the TMC26x settings - that were explained above - TMC4361A now sends
20-bit datagrams automatically.
In order to send cover datagrams to TMC26x motor stepper drivers, do as
follows:
Action:
 Set COVER_LOW (19:0) to the register values that need to be transferred.
Result:
A cover datagram is sent to the connected driver. COVER_DONE is set after data
transfer. The response of TMC26x is stored in COVER_DRV_LOW (19:0).
In case the TMC26x driver operates in SPI mode, COVER_DONE is also set when a
current datagram is transferred.
In order to enable COVER_DONE only for cover datagrams, do as follows:
Action:
 Set cover_done_only_for_covers = 1 (bit12 of SPI_OUT_CONF register 0x04).
Result:
COVER_DONE event is only set if a cover datagram is sent, not for current datagrams.
Automatic
Continuous
Streaming of
Cover Datagrams
for TMC26x
It is a common approach that the microcontroller continuously rewrites register values
for TMC26x to respond to possible voltage drops at the VS pin of TMC26x, which – if
they occur – prompt an internal register reset, by design.
TMC4361A provides an option to continuously rewrite the five configuration registers
of TMC26x, which take off workload from the microcontroller.
In order to activate automatic continuous streaming of TMC26x cover
datagrams, do as follows:
Action:
 Set autorepeat_cover_en = 1 (bit7 of SPI_OUT_CONF register 0x04).
Result:
In case cover datagrams are sent to TMC26x while autorepeat__cover_en = 1,
TMC4361A transfers a cover datagram every 2²⁰ clock cycle. Every time another
register is addressed, the cover datagrams are retransferred one after the other in
consecutive order; i.e. round-robin style.
i However, the transfer rate remains at one datagram per 2²⁰ clock cycles.
NOTE:
 When TMC26x is operating in SPI mode, current datagrams are also repeated, if
the value does not change; within one transfer interval cycle.
 In case a TMC26x register is rewritten manually by cover datagrams, this last
register value is, by definition, repeated.
 Automatic register changes executed by TMC4361A – e.g. automatic scaling value
transfers – are considered as well for repeated cover datagrams.
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Read entire documentation; especially the “Supplemental Directives” on page 223.
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