Texas Instruments TMS320 User Manual page 116

Hardware Interrupts
4.2.2 Disabling and Enabling Hardware Interrupts
4.2.3 Impact of Real-Time Mode Emulation on DSP/BIOS
4.2.3.1 Interrupt Behavior for C28x During Real-Time Mode
4-12
The DSP/BIOS online help describes HWI objects and their parameters. See
HWI Module in the TMS320 DSP/BIOS API Reference Guide for your
platform for reference information on the HWI module API calls.
Within a software interrupt or task, you can temporarily disable hardware
interrupts during a critical section of processing. The HWI_disable and
HWI_enable/HWI_restore functions are used in pairs to disable and enable
interrupts.
When you call HWI_disable, interrupts are globally disabled in your
application. On the C6000 platform, HWI_disable clears the GIE bit in the
control status register (CSR). On the C5000 and C2800 platforms,
HWI_disable sets the INTM bit in the ST1 register. On both platforms, this
prevents the CPU from taking any maskable hardware interrupt. Hardware
interrupts, therefore, operate on a global basis, affecting all interrupts, as
opposed to affecting individual bits in the interrupt enable register. To
reenable interrupts, call HWI_enable or HWI_restore. HWI_enable always
enables the GIE bit on the C6000 platform or clears the INTM bit in the ST1
register on the C5000 and C2800 platforms, while HWI_restore restores the
value to the state that existed before HWI_disable was called.
TI Emulation supports two debug execution control modes:
❏ Stop mode
❏ Real-time mode
Stop mode provides complete control of program execution, allowing for
disabling of all interrupts. Real-time mode allows time-critical interrupt service
routines to be performed while execution of other code is halted. Both
execution modes can suspend program execution at break events, such as
occurrences of software breakpoint instructions or specified program space
or data-space accesses.
In real-time mode, background codes are suspended at break events while
continuing to execute the time-critical interrupt service routines (also referred
to as foreground code.)
Real-time mode for C28x is defined by three different states:
❏ Debug Halt state