www.ti.com
Overview of the PIE Controller
the request directly to the CPU.
For multiplexed interrupt sources, each interrupt group in the PIE block has an associated flag register
(PIEIFRx) and enable (PIEIERx) register (x = PIE group 1 - PIE group 12). Each bit, referred to as y,
corresponds to one of the 8 MUXed interrupts within the group. Thus PIEIFRx.y and PIEIERx.y
correspond to interrupt y (y = 1-8) in PIE group x (x = 1-12). In addition, there is one acknowledge bit
(PIEACK) for every PIE interrupt group referred to as PIEACKx (x = 1-12). Figure 6-2 illustrates the
behavior of the PIE hardware under various PIEIFR and PIEIER register conditions.
Once the request is made to the PIE controller, the corresponding PIE interrupt flag (PIEIFRx.y) bit is
set. If the PIE interrupt enable (PIEIERx.y) bit is also set for the given interrupt then the PIE checks the
corresponding PIEACKx bit to determine if the CPU is ready for an interrupt from that group. If the
PIEACKx bit is clear for that group, then the PIE sends the interrupt request to the CPU. If PIEACKx is
set, then the PIE waits until it is cleared to send the request for INTx. See Section 6.3 for details.
• CPU Level
Once the request is sent to the CPU, the CPU level interrupt flag (IFR) bit corresponding to INTx is set.
After a flag has been latched in the IFR, the corresponding interrupt is not serviced until it is
appropriately enabled in the CPU interrupt enable (IER) register or the debug interrupt enable register
(DBGIER) and the global interrupt mask (INTM) bit.
SPRUFB0C – September 2007 – Revised May 2009 Peripheral Interrupt Expansion (PIE) 123
Submit Documentation Feedback
To Next Page
Loading...
Need help?
General
