psd511b1 STMicroelectronics, psd511b1 Datasheet - Page 98

• Manufacturer Part Number: psd511b1
• Description: Low Cost Field Programmable Microcontroller Peripherals
• Manufacturer: STMicroelectronics

9.7
Interrupt
Controller
Table 28. Interrupt Priority Table
General Description
The PSD5XX includes logic for sensing, masking, priority decoding and identifying up to
eight internal interrupts. The PSD5XX interrupt controller can generate interrupts from two
dedicated PPLD product terms, two PPLD Macrocell outputs and four terminal-count
outputs of the Counter/Timer unit.
The four interrupts generated by the PPLD can be user defined using the WSI PSDsoft
Windows compatible PC based software. Figure 45 details the basic building blocks
of the PSD5XX Interrupt Controller and Figure 46 shows its interface with other sections of
the PSD5XX.
Features
The PSD5XX interrupt controller has the following features:
9.7.1 Interrupt Operation
On RESET all Registers and Latches are cleared and all interrupts are masked. During
initialization of the interrupt controller, relevant interrupts are un-masked and defined
whether EDGE or LEVEL sensitive. When one or more interrupts are raised high,
the “interrupt request latch” latches in all the non-masked interrupts. A 3-bit priority encoder
assigns the priority to the non-masked pending interrupts. The MCU (microcontroller)
can clear the Edge-sensitive pending interrupts by reading the “Interrupt Read Clear
Register”. Level-sensitive interrupts continue to be pending even after the MCU reads the
“Interrupt Read Clear Register”. The MCU would typically service each interrupt in
sequence according to priority. Refer to Table 28 regarding priorities of various interrupts.
Any of these interrupts trigger a GLOBAL interrupt output available as an input to the PPLD
(INTR2PLD) and as output at port E (PE2). Refer to Figures 45 and 46 for details of the
interrupt architecture.
Can accept eight interrupt inputs
PPLD product terms, PPLD Macrocell outputs and Terminal Counts (TCs) of
Counter/Timers can cause interrupts.
Interrupts generated from the PPLD canbe user defined.
All interrupt inputs are priority decoded, IR7 has highest priority and IR0 the
lowest priority.
Each interrupt can be configured as either EDGE or LEVEL sensitive using the
EDGE/LEVEL register.
Each interrupt can be individually masked using a mask register.
At RESET all interrupts are MASKED.
Interrupt Request Latch provides the status of all interrupts.
Reading an Interrupt vector location clears the corresponding pending interrupt.
Any of these interrupts trigger a GLOBAL interrupt output available as an output at port
E (PE2) and/or as an input to the PPLD.
Interrupt
IR 7
IR 6
IR 5
IR 4
IR 3
IR 2
IR 1
IR 0
HIGHEST
LOWEST
Priority
^
^
^
^
^
^
PSD5XX Family
95