ST92F124/F150/F250 - INTERRUPTS
5.7 STANDARD INTERRUPTS (CAN AND SCI-A)
The two on-chip CAN peripherals generate 4 inter-
rupt sources each. The SCI-A interrupts are
mapped on a single interrupt channel. The map-
ping is shown in the following table.
The priority level of the interrupt channels can be
programmed to one of eight priority levels using
the SIPLRL and SIPLRH control registers.
The two MSBs of the priority level are user pro-
grammable. For each interrupt group, the even
channels (E0, F0, G0, H0, I0) have an even priority
level (LSB of priority level is zero) and the odd
channels (E1, F1, G1, H1) have an odd priority lev-
el (the LSB of priority level is one). See Figure 52.
Table 21. Interrupt Channel Assignment
Interrupt Pairs
INTE0
Interrupt Source
CAN0_RX0
CAN0_RX1
CAN0_TX
INTE1
.
INTF0
Figure 52. Priority Level Examples
INTF1
CAN0_SCE
CAN1_RX0
CAN1_RX1
CAN1_TX
INTG0
INTG1
INTH0
INTH1
INTI0
PL2H PL1H PL2GPL1G PL2F PL1F PL2E PL1E
1
0
0
0
1
0
0
1
IPLRL
SOURCE PRIORITY
SOURCE PRIORITY
CAN1_SCE
SCI-A
INT.G0: 100=4
INT.G1:101=5
INT.E0: 010=2
INT.E1: 011=3
INTI1
Reserved
INT.H0: 000=0
INT.H1: 001=1
INT.F0: 100=4
INT.F1: 101=5
5.7.1 Functional Description
The SIPRL and SIPRH registers contain the inter-
rupt pending bits of the interrupt sources. The
pending bits are set by hardware on occurrence of
a rising edge event. The pending bits are reset by
hardware when the interrupt is acknowledged.
All interrupt channels share a single interrupt vec-
tor register (SIVR). Bits 1 to 4 of the SIVR register
change according to the interrupt channel which
has the highest priority pending interrupt request.
If more than one interrupt channel has pending in-
terrupt requests with the same priority, then an in-
ternal daisy chain decides the interrupt channel
that will be served. INTE0 is first in the internal dai-
sy chain and INTI0 is last.
The SIMRL and SIMRH registers are used to
mask the interrupt requests coming from the inter-
rupt sources. Resetting the bits of these registers
prevents the interrupt requests being sent to the
ST9 core.
The SITRL and SITRH registers are used to select
the edge sensitivity of the interrupt channel (rising
or falling edge). As the SCI-A and CAN interrupt
events are rising edge events, all bits in the SITRL
register and ITEI0 bit in SITRH register must be
set to 1.
An overrun flag is associated with each interrupt
channel. If a new interrupt request comes before
the earlier interrupt request is acknowledged then
the corresponding overrun flag is set.
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