Pulse-Width Modulator for Motor Control (PWMMC)
Control Logic Block
ISENS1 and ISENS0 — Current Sense Correction Bits
These read/write bits select the top/bottom correction scheme as shown in
Table 12-7.
Table 12-7. Correction Methods
Current Correction Bits
Correction Method
ISENS1 and ISENS0
00
Bits IPOL1, IPOL2, and IPOL3 are used for correction.
01
Current sensing on pins IS1, IS2, and IS3 occurs during the
dead-time.
10
Current sensing on pins IS1, IS2, and IS3 occurs at the half
11
cycle in center-aligned mode and at the end of the cycle in
edge-aligned mode.
1. The polarity of the ISx pin is latched when both the top and bottom PWMs are off. At
the 0% and 100% duty cycle boundaries, there is no dead-time, so no new current
value is sensed.
2. Current is sensed even with 0% and 100% duty cycle.
NOTE:
The ISENSx bits are not buffered. Changing the current sensing method can affect
the present PWM cycle.
LDOK— Load OK Bit
This read/write bit loads the prescaler bits of the PMCTL2 register and the entire
PMMODH/L and PWMVALH/L registers into a set of buffers. The buffered
prescaler divisor, PWM counter modulus value, and PWM pulse will take effect
at the next PWM load. Set LDOK by reading it when it is logic 0 and then writing
a logic 1 to it. LDOK is automatically cleared after the new values are loaded or
can be manually cleared before a reload by writing a 0 to it. Reset clears LDOK.
1 = Load prescaler, modulus, and PWM values.
0 = Do not load new modulus, prescaler, and PWM values.
NOTE:
The user should initialize the PWM registers and set the LDOK bit before enabling
the PWM.
A PWM CPU interrupt request can still be generated when LDOK is 0.
PWMEN — PWM Module Enable Bit
This read/write bit enables and disables the PWM generator and the PWM pins.
When PWMEN is clear, the PWM generator is disabled and the PWM pins are
in the high-impedance state (unless OUTCTL = 1).
When the PWMEN bit is set, the PWM generator and PWM pins are activated.
For more information, see 12.7 Initialization and the PWMEN Bit.
1 = PWM generator and PWM pins enabled
0 = PWM generator and PWM pins disabled
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA Pulse-Width Modulator for Motor Control (PWMMC)
Data Sheet
159
FREESCALE [ Freescale ]
