System Integration Unit (SIU)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
6-50
Freescale Semiconductor
Preliminary
6.4.1.2
Pad Configuration
The pad configuration registers (SIU_PCR) in the SIU allow software control of the static electrical
characteristics of external pins. The PCRs can select the multiplexed function of a pin, selection of pullup
or pulldown devices, the slew rate of I/O signals, open drain mode for output pins, and hysteresis.
6.4.2
Reset Control
The reset controller logic is located in the SIU. See
Section 7.4, “Reset Configuration
details.
6.4.3
External Interrupt
There are sixteen external interrupt inputs, IRQ0–IRQ15, to the SIU. The IRQ
n
inputs can be configured
for rising- or falling-edge events or both. Each IRQ
n
input has a corresponding flag bit in the external
interrupt status register (SIU_EISR). The flag bits for the IRQ4–IRQ15 inputs are ORed together to form
one interrupt request to the interrupt controller. The flag bits for the IRQ1–IRQ4 inputs can generate an
interrupt request to the interrupt controller or a DMA transfer request to the DMA controller. The flag bit
for IRQ0 can generate an interrupt request if SIU_DIRSR[31] is 0, or is disabled if SIU_DIRSR[0] is 1.
shows the DMA and interrupt request connections to the interrupt and DMA controllers.
Any pin used as an external interrupt must be configured in its SIU_PCR as a GPIO in input mode. In
addition, either rising and/or falling edge must be enabled in the SIU_IREER, or SIU_IFEER.
Two external inputs from pins PD11 and PD10 connect through the SIU to the critical interrupt input to
the Z0 and Z1 cores, respectively. These signals should be used as non maskable interrupt (NMI) inputs.
The SIU contains an overrun interrupt enable for each IRQ and one combined overrun interrupt request to
the interrupt controller which is the logical OR of the individual overrun requests’ flags. Only the
combined overrun interrupt request is used in the device, and the individual overrun requests are not
connected.
Each IRQ pin has a programmable filter for rejecting glitches on the IRQ signals. The filter length for the
IRQ pins is specified in the external IRQ digital filter register (SIU_IDFR).
Table 6-30. SIU_RSR[BOOTCFG] Configuration
Value
Meaning
0b0
Boot from internal flash memory
0b1
CAN/SCI boot