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61 lines
2.7 KiB
Markdown
61 lines
2.7 KiB
Markdown
| Supported Targets | ESP32 | ESP32-S3 |
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| ----------------- | ----- | -------- |
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# IPC ISR Example
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This example demonstrates how to use the IPC ISR feature (which allows an IPC to run in the context of a High Priority Interrupt). The level of the IPC ISR interrupt depends on the `CONFIG_ESP_SYSTEM_CHECK_INT_LEVEL` option. The IPC ISR feature can be useful in cases where users need to quickly get the state of the other CPU (consult the [IPC documentation](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/ipc.html)). The `asm_funcs.S` file contains the callback that will be run on the other core. The callback should be fairly simple and must be entirely in assembly.
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The first assembly callback `get_ps_other_cpu()` demonstrates a callback that simply returns the `PS` register of other core.
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The second assembly callback `extended_ipc_isr_asm()` demonstrates a more complex callback that uses a buffer (provided as the callback's argument) to save some registers and return multiple values from the callback. The callback's `void *arg` points to a buffer containing the following:
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- `uint32_t regs[];` that gives the callback an area to save some of the CPUs registers. Saving the registers gives the callback more scratch registers to use.
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- `uint32_t in[];` that gives the callback multiple input arguments
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- `uint32_t out[];` that gives the callback multiple output arguments
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The `extended_ipc_isr_asm()` callback will simply save/restore registers to/from `regs[]`, then use the arguments passed by `in[]` to do some work, then write the results to `out[]`.
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## How to use example
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### Hardware Required
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Example should be able to run on any commonly available ESP32 development board. The chip should have two cores.
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### Configure the project
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- `CONFIG_FREERTOS_UNICORE` - disabled,
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- `CONFIG_ESP_IPC_ISR_ENABLE` - enabled.
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```
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idf.py menuconfig
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```
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### Build and Flash
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```
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idf.py build flash monitor
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```
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the [Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for full steps to configure and use ESP-IDF to build projects.
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## Example output
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```
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I (304) example: Start
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I (304) example: call get_ps_other_cpu
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I (314) example: PS_INTLEVEL = 0x5
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I (314) example: PS_EXCM = 0x0
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I (324) example: PS_UM = 0x1
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I (324) example: call extended_ipc_isr_asm
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I (324) example: in[0] = 0x1
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I (334) example: in[1] = 0x2
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I (334) example: in[2] = 0x3
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I (334) example: out[0] = (in[0] | in[1] | in[2]) = 0x3
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I (344) example: out[1] = (in[0] + in[1] + in[2]) = 0x6
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I (354) example: out[2] = in[2] = 0x3
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I (354) example: out[3] = PS of other cpu = 0x25
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I (364) example: End
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```
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