mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 162

• Manufacturer Part Number: mcf51ac256a
• Description: Mcf51ac Flexis
• Manufacturer: Freescale Semiconductor, Inc

Analog Comparator (ACMPV3)
8.1.4
ACMP1 and ACMP2 share a single interrupt vector, located at address 0xFFD6:0xFFD7. When interrupts
are enabled for both ACMPs, the ACMP1SC[ACF] and ACMP2SC[ACF] bits must be polled to determine
which ACMP caused the interrupt.
8.1.5
8.1.5.1
The ACMPxSC[ACF] bit of the ACMPx modules can be used as one of the three FTM hardware
synchronization triggers. The ACMPx input is the second highest priority of the three hardware sync
triggers. ACMP1SC[ACF] is connected to FTM1 and ACMP2SC[ACF] is connected to FTM2.
The ACF bit can be configured to set on rising voltage inputs, falling voltage inputs or both rising and
falling inputs.
8.1.5.2
The ACMP1 module can be configured to connect the output of the analog comparator to FTM1 input
capture channel 0 by setting the SOPT2[ACIC1] bit. With ACIC1 set, the FTM1CH0 pin is not available
externally regardless of the configuration of the FTM1 module.
8.1.5.3
The ACMP2 module can be configured to connect the output of the analog comparator to TPM3 input
capture channel 0 by setting the SOPT2[ACIC2] bit. With ACIC2 set, the TPM3CH0 pin is not available
externally regardless of the configuration of the TPM3 module.
8.1.5.4
The ACMP1 module has the capability to send a hardware trigger to the ADC using the ACMP1SC[ACF]
bit. The ADC hardware trigger is enabled by the ADCSC2[ADTRG] bit. In addition, the hardware trigger
source must be selected with the SOPT2[ADHWTS1:ADHWTS0] bits. ADHWTS1:ADHWTS0 = 0b01
selects ACMP1 as the ADC hardware trigger.
Typical usage is for the ACMP to be constantly monitoring a voltage level and the ADC to be off or
monitoring a different signal until a voltage of interest is observed on the ACMP1 input. The ADC can
then measure the same signal for a more accurate reading. Since ACMP1– and AD1P9 share the same pin
as do ACMP1+ and AD1P8, taking an ADC reading on the ACMP1 inputs is trivial and doesn’t require
separate pins for ACMP1 and ADC.
8-2
Interrupt Vectors
ACMPx Module-to-Module Interconnects
ACMPx to FTMx Synchronization Trigger
ACMP1 to FTM1 input capture
ACMP2 to TPM3 input capture
ACMP1 to ADC Hardware Trigger
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor