Datasheet

TMC4361A Datasheet | Document Revision 1.22 • 2017-JAN-12
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Read entire documentation; especially the “Supplemental Directives” on page 224.
 MAIN MANUAL 
The values of ramp parameters, which are not selected by one of the four
shadow options stay as originally configured, until the register is changed
through an SPI write request.
Also, the last stage of the shadow register pipeline retains the values until
they are overwritten by an SPI write request if no cyclic shadow registers
are selected.
Up to 15 internal start signals can be skipped before the shadow register transfer is
executed.
In order to skip a defined number of internal start signals for the shadow
transfer, do as follows:
Action:
 Set shadow_option according to your specification.
 Set start_en (4) = 1 and select one or more trigger_events ( START_CONF register
0x02)
 OPTIONAL CONFIGURATION: Set cyclic_shadow_regs = 1.
 Set SHADOW_MISS_CNT ≠ 0 ( START_CONF register 0x02) according to the
number of consecutive internal start signals that you specify to be ignored.
Result:
The shadow register transfer is not executed with every internal start signal. Instead,
the specified number of start signals is ignored until the shadow transfer is executed
through the ( SHADOW_MISS_CNT +1)
th
start signal.
The following figure shows an example of how to make use of SHADOW_MISS_CNT ,
in which the shadow register transfer is illustrated by an internal signal
sh_reg_transfer. The signal miss counter CURRENT_MISS_CNT can be read out at
register address START_CONF (23:20):
Figure 41: SHADOW_MISS_CNT Parameter for several internal Start Signals
Internal calculations to transfer the requested shadow BOW values into
internal structures require at most (320 / f
CLK
) [sec]. before any shadow
register transfer is prompted, it is necessary to wait for the completion of
all internal calculations for the shadow bow parameters.
In order to make this better understood the following example is provided
for a double-stage shadow pipeline for S-shaped ramps:
PRECONDITION:
Shadow register transfer is activated ( start_en (1) = 1 and one or more trigger_events
are selected) for S-shaped ramps ( shadow_option = b’01)
Action
 Set SH_REG0 , SH_REG1 , SH_REG2 (shadow register for VMAX , AMAX , DMAX ).
 Set SH_REG3 , SH_REG4 , SH_REG5 , SH_REG6 (shadow register for BOW1 … 4 ).
 Ensure that no shadow register transfer occurs during the next 320 / f
CLK
[s].
Result:
Shadow register transfer can be initiated after this time span.
SPI
shadow_miss_cnt
= 0
internal start signal
shadow_miss_cnt
= 5
shadow_miss_cnt
= 2
1 2
3
4 5 0
1
2
0
1 2
0
1
0
current_miss_cnt
sh_reg_transfer
!
AREAS OF
SPECIAL
CONCERN
Delayed Shadow
Transfer
AREAS OF
SPECIAL
CONCERN
!