ST7FMC1K2B3 STMICROELECTRONICS [STMicroelectronics], ST7FMC1K2B3 Datasheet - Page 181

• Manufacturer Part Number: ST7FMC1K2B3
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

MOTOR CONTROLLER (Cont’d)
Hall sensors (or equivalent sensors providing posi-
tion information) are widely used for motor control.
There are two cases to be considered:
– BLDC motor or six-step synchronous motor
– BLAC, asynchronous or motors supplied with 3-
Hall sensors are usually arranged in a 120° config-
uration. In that case they provide 3 ppr with both
rising and falling edge triggering; the tachogenera-
tor measurement method can therefore be ap-
plied. The main difference lies in the fact that one
must use the position information they provide.
This can be done using the three MCIx pins and
the analog multiplexer to know which of the 3 sen-
sors toggled; an interrupt is generated just after
the expected transition (refer to
As described in
configured depending on the selected sensor. This
means that most of Delay Manager registers are
used for a different purpose, with modified func-
tionalities.
For greater precision, the MTIM Up-counter is ex-
tended to 16 bits using MTIM and an additional
MTIML register. On a capture event, the current
counter value is captured and the counter
Figure 101. Hall sensor period acquisition using MTIM timer
drive; “Sensor Mode” is recommended in this
case, as most tasks are performed by hardware
in the Delay Manager
phase sinewave-modulated PWM signals in gen-
eral; in this case “Speed Sensor Mode” allows
high accuracy speed measurement (the Sensor
Mode of the Delay Manager being unsuitable for
sinewave generation). Position information is
handled by software to lock the statoric field to
the rotoric one for driving synchronous motors.
Period measurements
MCIC: Hall Sensor 3
MCIA: Hall Sensor 1
MCIB: Hall Sensor 2
Tacho Capture
Interrupts
Figure
102, the MTIM Timer is re-
C
Figure
C
C
1-2
101).
C
2-3
1 mechanical cycle
C
3-1
C
1-2
[MTIM:MTIML] is cleared. The counting direction
is not affected by the EDIR bit when using an en-
coder sensor.
A 16-bit capture register is used to store the cap-
tured value of the extended MTIM counter: the
speed result will be either a period in clock cycles
or a number of encoder pulses. This 16-bit register
is mapped in the MZREG and MZPRV register ad-
dresses. To ensure that the read value is not cor-
rupted between the high and low byte accesses, a
read access to the MSB of this register (MZREG)
locks the LSB (ie MZPRV content is locked) until it
is read and any other capture event in between
these two accesses is discarded.
A compare unit allows a maximum value to be en-
tered for the tacho periods. If the 16-bit counter
[MTIM:MTIML] exceeds this value, a Speed Error
interrupt is generated. This may be used to warn
the user that the tachogenerator signal is lost
(wires disconnected, motor stalled,...). As 8-bit ac-
curacy is sufficient for this purpose, only the MS-
Byte of the counter (i.e. MTIM) is compared to 8-bit
compare register, mapped in the MDREG register
location. The LSByte is nevertheless compared
with a fixed FFh value. Available values for com-
parison are therefore FFFFh, FEFFh, FDFFh, ...,
01FFh, 00FFh.
Note: This functionality is not useful when using
an encoder. With an encoder, user must monitor
the captured values by software during the period-
ic capture interrupts: for instance, when driving an
AC motor, if the values are too low compared to
the stator frequency, a software interrupt may be
triggered.
C
2-3
C
3-1
C
C
ST7MC1xx/ST7MC2xx
C
C
181/309
C
1