TMS320F2810, TMS320F2811, TMS320F2812
TMS320C2810, TMS320C2811, TMS320C2812
SPRS174T – APRIL 2001 – REVISED MAY 2012
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3.2.12 Peripheral Interrupt Expansion (PIE) Block
The PIE block serves to multiplex numerous interrupt sources into a smaller set of interrupt inputs. The
PIE block can support up to 96 peripheral interrupts. On the F281x and C281x, 45 of the possible
96 interrupts are used by peripherals. The 96 interrupts are grouped into blocks of 8 and each group is fed
into 1 of 12 CPU interrupt lines (INT1 to INT12). Each of the 96 interrupts is supported by its own vector
stored in a dedicated RAM block that can be overwritten by the user. The vector is automatically fetched
by the CPU on servicing the interrupt. It takes 8 CPU clock cycles to fetch the vector and save critical
CPU registers. Hence the CPU can quickly respond to interrupt events. Prioritization of interrupts is
controlled in hardware and software. Each individual interrupt can be enabled/disabled within the PIE
block.
3.2.13 External Interrupts (XINT1, XINT2, XINT13, XNMI)
The F281x and C281x support three masked external interrupts (XINT1, 2, 13). XINT13 is combined with
one non-masked external interrupt (XNMI). The combined signal name is XNMI_XINT13. Each of the
interrupts can be selected for negative or positive edge triggering and can also be enabled/disabled
(including the XNMI). The masked interrupts also contain a 16-bit free-running up-counter, which is reset
to zero when a valid interrupt edge is detected. This counter can be used to accurately time-stamp the
interrupt.
3.2.14 Oscillator and PLL
The F281x and C281x can be clocked by an external oscillator or by a crystal attached to the on-chip
oscillator circuit. A PLL is provided supporting up to 10-input clock-scaling ratios. The PLL ratios can be
changed on-the-fly in software, enabling the user to scale back on operating frequency if lower power
operation is desired. Refer to
Section 6
, Electrical Specifications, for timing details. The PLL block can be
set in bypass mode.
3.2.15 Watchdog
The F281x and C281x support a watchdog timer. The user software must regularly reset the watchdog
counter within a certain time frame; otherwise, the watchdog will generate a reset to the processor. The
watchdog can be disabled if necessary.
3.2.16 Peripheral Clocking
The clocks to each individual peripheral can be enabled/disabled to reduce power consumption when a
peripheral is not in use. Additionally, the system clock to the serial ports (except eCAN) and the event
managers, CAP and QEP blocks can be scaled relative to the CPU clock. This enables the timing of
peripherals to be decoupled from increasing CPU clock speeds.
3.2.17 Low-Power Modes
The F281x and C281x devices are fully static CMOS devices. Three low-power modes are provided:
IDLE:
Place CPU in low-power mode. Peripheral clocks may be turned off selectively and only
those peripherals that must function during IDLE are left operating. An enabled interrupt
from an active peripheral will wake the processor from IDLE mode.
STANDBY:
Turns off clock to CPU and peripherals. This mode leaves the oscillator and PLL
functional. An external interrupt event will wake the processor and the peripherals.
Execution begins on the next valid cycle after detection of the interrupt event.
HALT:
Turns off the internal oscillator. This mode basically shuts down the device and places it
in the lowest possible power consumption mode. Only a reset or XNMI can wake the
device from this mode.
36
Functional Overview
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