st7pmc2s6 STMicroelectronics, st7pmc2s6 Datasheet - Page 217

• Manufacturer Part Number: st7pmc2s6
• Description: 8-bit Mcu For Automotive With Nested Interrupts, Flash, 10-bit Adc, Brushless Motor Control, 5 Timers, Spi, Linsci?
• Manufacturer: STMicroelectronics

ST7MC1K2-Auto, ST7MC1K6-Auto, ST7MC2S4-Auto, ST7MC2S6-Auto
Note:
Autoswitched mode
In this mode, using the hardware commutation event C
MCOMP register content is automatically computed in real time as described below and in
Figure
The C (either C
When a Z
previous captured value is shifted into the MZPRV register and the MTIM timer is reset. See
Figure
When a Z
register and the MTIM timer is reset.
One of these two registers, (when the SC bit = 0 in the MCRC register and depending on the
DCB bit in the MCRA register), is multiplied with the contents of the MWGHT register and
divided by 256. The result is loaded in the MCOMP compare register, which automatically
triggers the next hardware commutation (C
The result of the 8*8 bit multiplication, once written in the MCOMP register is compared with
the current MTIM value to check that the MCOMP value is not already less than the MTIM
value due to the multiplication time. If MCOMP <= MTIM, a C
immediately and the MCOMP value is overwritten by the MTIM value.
Table 97.
After each shift operation the multiply is recomputed for greater precision.
Using either the MZREG or MZPRV register depends on the motor symmetry and type.
The MWGHT register gives directly the phase shift between the motor driven voltage and
the BEMF. This parameter generally depends on the motor and on the speed.
Setting the SC bit in the MCRC register enables the simulated commutation event (C
generation. This means that a write access is possible to the MCOMP register and the
MTIM value is compared directly with the value written by software in the MCOMP register
to generate the C
the MCOMP register. This means that if the SC bit is set and no write access is done to the
MCOMP register, the C event never occurs because no comparison is made between
MCOMP and MTIM. Therefore, it is recommended in autoswitched mode, when using
software commutation feature (SC bit is set) and for a normal event sequence, the
corresponding value to be put in MCOMP has to be written during the Z interrupt routine
(because MTIM has just been reset), so that there is no spurious comparison. If the SC bit is
set during a Z event interrupt, then, the result of the 8*8 bits hardware multiplication can be
overwritten by software in the MCOMP register. When simulated commutation mode is
enabled, the event sequence is no longer respected, meaning that the peripheral accepts
consecutive commutation events and does not necessarily wait for a D event after a C
event. In this case the MCOMP register can be written immediately after the previous C
event, in the C interrupt service routine for example.
94.
74.
DCB bit
H
S
0
1
event occurs, the value written in the MZREG register is shifted into the MZPRV
event occurs the MTIM timer value is captured in the MZREG register, the
Multiplier result
S
or C
S
event. The comparison is enabled as soon as a write access is done to
H
) event has no effect on the contents of the MTIM timer.
MCOMP = MWGHT x MZREG/256
MCOMP = MWGHT x MZPRV/256
H
event).
Commutation delay
H
(SC bit reset in MCRC register), the
H
event is generated
On-chip peripherals
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S
s
)