NXP Semiconductors MPC5644A, Reference Manual, Page: 741 / 1735

Reaction Module (REACM)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor 741
Figure 23-38. Modulation phases
The current through the injectors are initially zero since the reaction channel output is in the OFF state as
configured by the DOFF[2:0] field. The eTPU timer window is at the OFF state as well. The modulation
starts when the eTPU channel time window switches to ON state. Modulation
phase A starts at this time
as described in Figure 23-38 . The modulation word 0 is used. In this application this phase corresponds to
the Boosted Peak phase . This process allows the fuel injection to start sooner because of the sharp edge of
the current which is important for a precise control of the fuel to be injected. Phase A is the setup to execute
a Threshold-Threshold modulation but note that only I0 value is used since the phase advances when a
certain current is achieved. The following is a description of the bit fields in the Modulation word in order
to execute the modulation described in
phase A :
• LOOP = 0
• The initial value should be HOD (IOSS = 1)
• Threshold-Threshold modulation mode is obtained with MM = 00
• This phase ends when the threshold value I0 is achieved (SM = 11)
• Necessary to have HOD = 111 for boosted operation and sensor active, LOD setting is not
important in this case since it is not used
• I0 is read from Threshold Bank by using THRESPT = 0x0 that points to address 0 of this bank
• I1 is read from Threshold Bank by using (T 1) = 0x1
• Hold-off timer is not used, therefore HDOFFPT can have any value (X)
C
a b c e d
timer
control
signal
Current in
Injector
time
time
OFF
ON
OFF
A B D
modu
lat
ion word 0
modu
lat
ion word 1
modu
lat
ion word 2
modu
lat
ion word 3
I0
I3
I2
I5
I4
eTPU