NXP Semiconductors MPC5644A, Reference Manual, Page: 740 / 1735

Reaction Module (REACM)
MPC5644A Microcontroller Reference Manual, Rev. 6
740 Freescale Semiconductor
modulation and use the same threshold values. Note also that the data stored in the Threshold bank in this
case is also shared between these channels. This is an important feature of the Reaction Module
architecture since it allows the sharing of resources and therefore provides savings in size without
compromising the module functionality.
Figure 23-38 shows an example of the required current levels through Injector A and B. In order to
generate this waveform, the Reaction Module uses one Modulation Control Word for each one of the five
phases of the waveform from A through F. In this example the Module should be configured in the
following way:
1. Set the REACM_CHRR0 CHIR[3:0] = 0x0, thus routing eTPU channel 0 to reaction channel 0
2. Set the REACM_CHRR1 CHIR[3:0] = 0x1, thus routing eTPU channel 1 to reaction channel 1
3. Set the REACM_CHRR0 ADCR[3:0] = 0x0, thus routing ADC TAG 0 to reaction channel 0
4. Set the REACM_CHRR1 ADCR[3:0] = 0x0, thus routing ADC TAG 0 to reaction channel 1
5. Program Modulation Word Control bank according to Figure 23-39
6. Program Shared Timer Bank REACM_STBK for addresses from 0 through 3 with timing intervals
related to the duration of phases A,B,C and D respectively.
7. Program appropriate values in the Threshold Bank. Since threshold-threshold modulation is to be
used in this example, four pairs of values should be provided for phases A,B,C and D respectively.
Each pair corresponds to one address of the REACM_THBK starting at address 0x0400.
8. Program configuration registers for both channels, REACM_CHCR0/1. The parameters are
DOFF[2:0] which defines the OFF state of the channel outputs and the
MODULATION_ADDR = 0x0, which defines the address of the Modulation Control word. It is
assumed that the Modulation Word zero is the first word to be accessed by both channels. Since
four Modulation words will be used the addresses will be incremented by the reaction channel as
needed, thus only the address for the first word is required. Note that
MODULATON_ADDR = 0x0 points to the first Modulation Word in the Modulation Word Bank.
9. Program the prescalers HPRE and TPRE in the REACM_TCR register. Also enable the prescalers
by setting the TPREN and HPREN bits in the REACM_MCR register.
10. Enable channels CH0 and CH1 to start the modulation sequence by programing field CHEN = 01
on REACM_CHCR1/0 registers. At this time the Reaction channel CH0 accesses the Modulation
Control word zero and switches to ON state as defined by the data stored HOD[2:0] field. Up to
this point any activity in the eTPU channel or income ADC result is ignored by the Reaction
module. After CHEN field is programed, the reaction channels wait until a timer window is
initiated by eTPU for the modulation process to start.