mirror of
https://github.com/espressif/esp-idf.git
synced 2025-10-31 13:09:38 +00:00
70 lines
3.2 KiB
ReStructuredText
70 lines
3.2 KiB
ReStructuredText
High-Level Interrupts
|
|
=====================
|
|
|
|
.. toctree::
|
|
:maxdepth: 1
|
|
|
|
The Xtensa architecture has support for 32 interrupts, divided over 8 levels, plus an assortment of exceptions. On the {IDF_TARGET_NAME}, the interrupt mux allows most interrupt sources to be routed to these interrupts using the :doc:`interrupt allocator <../api-reference/system/intr_alloc>`. Normally, interrupts will be written in C, but ESP-IDF allows high-level interrupts to be written in assembly as well, allowing for very low interrupt latencies.
|
|
|
|
Interrupt Levels
|
|
----------------
|
|
|
|
===== ================= ====================================================
|
|
Level Symbol Remark
|
|
===== ================= ====================================================
|
|
1 N/A Exception and level 0 interrupts. Handled by ESP-IDF
|
|
2-3 N/A Medium level interrupts. Handled by ESP-IDF
|
|
4 xt_highint4 Normally used by ESP-IDF debug logic
|
|
5 xt_highint5 Free to use
|
|
NMI xt_nmi Free to use
|
|
dbg xt_debugexception Debug exception. Called on e.g. a BREAK instruction.
|
|
===== ================= ====================================================
|
|
|
|
Using these symbols is done by creating an assembly file (suffix .S) and defining the named symbols, like this::
|
|
|
|
.section .iram1,"ax"
|
|
.global xt_highint5
|
|
.type xt_highint5,@function
|
|
.align 4
|
|
xt_highint5:
|
|
... your code here
|
|
rsr a0, EXCSAVE_5
|
|
rfi 5
|
|
|
|
For a real-life example, see the :component_file:`esp_system/port/soc/{IDF_TARGET_PATH_NAME}/dport_panic_highint_hdl.S` file; the panic handler interrupt is implemented there.
|
|
|
|
|
|
Notes
|
|
-----
|
|
|
|
- Do not call C code from a high-level interrupt; because these interrupts still run in critical sections, this can cause crashes.
|
|
(The panic handler interrupt does call normal C code, but this is OK because there is no intention of returning to the normal code
|
|
flow afterwards.)
|
|
|
|
- Make sure your assembly code gets linked in. If the interrupt handler symbol is the only symbol the rest of the code uses from this
|
|
file, the linker will take the default ISR instead and not link the assembly file into the final project. To get around this, in the
|
|
assembly file, define a symbol, like this::
|
|
|
|
.global ld_include_my_isr_file
|
|
ld_include_my_isr_file:
|
|
|
|
|
|
The symbol is called ``ld_include_my_isr_file`` here but can have any arbitrary name not defined anywhere else.
|
|
|
|
Then, in the component CMakeLists.txt, add this file as an unresolved symbol to the ld command line arguments::
|
|
|
|
target_link_libraries(${COMPONENT_TARGET} "-u ld_include_my_isr_file")
|
|
|
|
If using the legacy Make build system, add the following to component.mk, instead::
|
|
|
|
COMPONENT_ADD_LDFLAGS := -u ld_include_my_isr_file
|
|
|
|
|
|
This should cause the linker to always include a file defining ``ld_include_my_isr_file``, causing the ISR to always be linked in.
|
|
|
|
- High-level interrupts can be routed and handled using esp_intr_alloc and associated functions. The handler and handler arguments
|
|
to esp_intr_alloc must be NULL, however.
|
|
|
|
- In theory, medium priority interrupts could also be handled in this way. For now, ESP-IDF does not support this.
|
|
|