Chapter 16 Motor Controller (MC10B8CV1)
S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
610
Freescale Semiconductor
Setting RECIRC = 1 will also invert the effect of the S bit such that while S = 0, MnC0P or MnC1P will
generate the PWM signal and MnC0M or MnC1M will be a static low output. While S = 1, MnC0M or
MnC1M will generate the PWM signal and MnC0P or MnC1P will be a static low output. In this case the
active state of the PWM signal will be high.
for detailed information about the impact of SIGN and RECIRC bit on the PWM output.
16.4.1.3.3
RECIRC Bit
The RECIRC bit controls the flow of the recirculation current of the load. Setting RECIRC = 0 will cause
recirculation current to flow through the high side transistors, and RECIRC = 1 will cause the recirculation
current to flow through the low side transistors. The RECIRC bit is only active in (dual) full H-bridge
modes.
Effectively, RECIRC = 0 will cause a static high output on the output terminal not driven by the PWM,
RECIRC = 1 will cause a static low output on the output terminals not driven by the PWM. To achieve the
same current direction, the S bit behavior is inverted if RECIRC = 1.
,
, and
illustrate the effect of the RECIRC bit in (dual) full H-bridge modes.
RECIRC bit must be changed only while no PWM channel is operated in (dual) full H-bridge mode.
Table 16-12. Impact of RECIRC and SIGN Bit on the PWM Output
Output Mode
RECIRC
SIGN
MnCyM
MnCyP
(Dual) Full H-Bridge
0
0
PWM
(1)
1. PWM: The PWM signal is low active. e.g., the waveform starts with 0 in left aligned mode. Output M generates the PWM signal.
Output P is static high.
1
(Dual) Full H-Bridge
0
1
1
PWM
(Dual) Full H-Bridge
1
0
0
PWM
(2)
2. PWM: The PWM signal is high active. e.g., the waveform starts with 1 in left aligned mode. output P generates the PWM signal.
Output M is static low.
(Dual) Full H-Bridge
1
1
PWM
0
Half H-Bridge: PWM on MnCyM
Don’t care
Don’t care
PWM
—
(3)
3. The state of the output transistors is not controlled by the motor controller.
Half H-Bridge: PWM on MnCyP
Don’t care
Don’t care
—
PWM
