Freescale Semiconductor Demonstration Board for Freescale MC9S12XHY256 Microcontroller DEMO9S12XHY256 DEMO9S12XHY256 Manuale Utente

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Freescale Semiconductor

Assuming RECIRC = 0 (the active state of the PWM signal is low), when the S bit for the corresponding
channel is cleared, MnC0P (if the PWM channel number is even, n = 0, 1, 2, 3, see

) or MnC1P

(if the PWM channel number is odd, n = 0, 1, 2, 3, see

), outputs a logic high while in (dual)

full H-bridge mode. In half H-bridge mode the state of the S bit has no effect. The PWM output signal is
generated on MnC0M (if the PWM channel number is even, n = 0, 1, 2, 3, see

(if the PWM channel number is odd, n = 0, 1, 2, 3).

Assuming RECIRC = 0 (the active state of the PWM signal is low), when the S bit for the corresponding
channel is set, MnC0M (if the PWM channel number is even, n = 0, 1, 2, 3, see

) or MnC1M

(if the PWM channel number is odd, n = 0, 1, 2, 3, see

), outputs a logic high while in (dual)

full H-bridge mode. In half H-bridge mode the state of the S bit has no effect. The PWM output signal is
generated on MnC0P (if the PWM channel number is even, n = 0, 1, 2, 3, see

) or MnC1P (if

the PWM channel number is odd, n = 0, 1, 2, 3).

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.

See

for detailed information about the impact of SIGN and RECIRC bit on the PWM output.

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

(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