NXP Semiconductors MPC5644A, Reference Manual, Page: 736 / 1735

Reaction Module (REACM)
MPC5644A Microcontroller Reference Manual, Rev. 6
736 Freescale Semiconductor
23.9.1 Interrupt sources
There are several sources of interrupts that indicates a faulty condition:
• MAXL: maximum ADC result value was reached
• OCDF: open circuit detected which indicates an open circuit and thus a potential malfunction in
the circuitry controlled by the Reaction Module. Note that differently from the TAER, this flag
does not indicate a faulty condition in the channel but in the circuit outside the device.
• SCDF: short circuit detected which indicates a short circuit was detected on the off-chip logic
controlled by the reaction channel.
• TAER: timer allocation error which indicates a required Timer resource was not allocated properly
thus leading to faulty operation of the Reaction module.
• SQER: sequencer error occurred meaning that the timer input signal was deasserted in a
modulation phase with SM != 00.
23.10 Use cases
Figure 23-35 shows an example of the Reaction Module used to control an Injector solenoid. Note that this
is a dual injector which is also called banked injector. Two Reaction channels are used to control this
injector.
The injector Boost transistor on the top applies a higher voltage in order to minimize the time necessary
for the injector to start injecting fuel. Transistors A and B control which injector is active in the injector
bank. A sensor resistor is used to feed the current flowing through the solenoid back to the on-chip ADC.
The current is sampled by the ADC and the result is sent to the Reaction Module, allowing closed loop
control.
NOTE
This injector bank architecture does not allow both injectors to operate at the
same time since the sensor in the feedback loop is shared by both injectors.