Interrupt Controller (CF1_INTC)
MCF51CN128 Reference Manual, Rev. 6
Freescale Semiconductor
8-7
The basic ColdFire interrupt controller supports up to 63 request sources mapped as nine priorities for each
of the seven supported levels (7 levels
×
9 priorities per level). Within the nine priorities within a level, the
mid-point is typically reserved for package-level IRQ inputs. The levels and priorities within the level
follow a descending order: 7 > 6 > ... > 1 > 0.
The HCS08 architecture supports a 32-entry exception vector table: the first two vectors are reserved for
internal CPU/system exceptions and the remaining are available for I/O interrupt requests. The
requirement for an exact match between the interrupt requests and priorities across two architectures
means the sources are mapped to a sparsely-populated two-dimensional ColdFire array of seven interrupt
levels and nine priorities within the level. The following association between the HCS08 and ColdFire
vector numbers applies:
ColdFire Vector Number = 62 + HCS08 Vector Number
The CF1_INTC performs a cycle-by-cycle evaluation of the active requests and signals the highest-level,
highest-priority request to the V1 ColdFire core in the form of an encoded interrupt level and the exception
vector associated with the request. The module also includes a byte-wide interface to access its
programming model. These interfaces are shown in the simplified block diagram of