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dedic_gpio: mention the overhead of using driver API

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morris 2022-05-05 14:46:29 +08:00
parent 3a5fdfe35a
commit 407b693646
2 changed files with 34 additions and 48 deletions
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1
docs/docs_not_updated/esp32c2.txt
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@ -91,7 +91,6 @@ api-reference/peripherals/secure_element
api-reference/peripherals/temp_sensor
api-reference/peripherals/spi_slave_hd
api-reference/peripherals/i2c
api-reference/peripherals/dedic_gpio
api-reference/peripherals/index
api-reference/kconfig
api-reference/network/esp_openthread

81
docs/en/api-reference/peripherals/dedic_gpio.rst
View File

@ -72,20 +72,47 @@ GPIO Bundle Operations
* - Read the value that output from bundle
- :cpp:func:`dedic_gpio_bundle_read_in`
.. note::
Using the above functions might not get a high GPIO flip speed because of the overhead of function calls and the bit operations involved inside. Users can try `Manipulate GPIOs by Assembly Code <#manipulate-gpios-by-writing-assembly-code>`__ instead to reduce the overhead but should take care of the thread safety by themselves.
Manipulate GPIOs by Writing Assembly Code
------------------------------------------
For advanced users, they can always manipulate the GPIOs by writing assembly code or invoking CPU Low Level APIs. The usual procedure could be:
1. Allocate a GPIO bundle: :cpp:func:`dedic_gpio_new_bundle`
2. Query the mask occupied by that bundle: :cpp:func:`dedic_gpio_get_out_mask` or/and :cpp:func:`dedic_gpio_get_in_mask`
3. Call CPU LL apis (e.g. `cpu_ll_write_dedic_gpio_mask`) or write assembly code with that mask
4. The fasted way of toggling IO is to use the dedicated "set/clear" instructions:
.. only:: esp32s2 or esp32s3
- Set bits of GPIO: ``set_bit_gpio_out imm[7:0]``
- Clear bits of GPIO: ``clr_bit_gpio_out imm[7:0]``
- Note: Immediate value width depends on the number of dedicated GPIO channels
.. only:: esp32c2 or esp32c3
- Set bits of GPIO: ``csrrsi rd, csr, imm[4:0]``
- Clear bits of GPIO: ``csrrci rd, csr, imm[4:0]``
- Note: Can only control the lowest 4 GPIO channels
.. only:: esp32s2
.. note::
The functions above just wrap the customized instructions defined for {IDF_TARGET_NAME}, for the details of those instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *IO MUX and GPIO Matrix (GPIO, IO_MUX)* [`PDF <{IDF_TARGET_TRM_EN_URL}#iomuxgpio>`__].
For details of supported dedicated GPIO instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *IO MUX and GPIO Matrix (GPIO, IO_MUX)* [`PDF <{IDF_TARGET_TRM_EN_URL}#iomuxgpio>`__].
.. only:: esp32s3
.. note::
The functions above just wrap the customized instructions defined for {IDF_TARGET_NAME}, for the details of those instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *Processor Instruction Extensions (PIE) (to be added later)* [`PDF <{IDF_TARGET_TRM_EN_URL}#pie>`__].
For details of supported dedicated GPIO instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *Processor Instruction Extensions (PIE) (to be added later)* [`PDF <{IDF_TARGET_TRM_EN_URL}#pie>`__].
.. only:: esp32c2 or esp32c3
.. note::
The functions above just wrap the customized instructions defined for {IDF_TARGET_NAME}, for the details of those instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *ESP-RISC-V CPU* [`PDF <{IDF_TARGET_TRM_EN_URL}#riscvcpu>`__].
For details of supported dedicated GPIO instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *ESP-RISC-V CPU* [`PDF <{IDF_TARGET_TRM_EN_URL}#riscvcpu>`__].
Some of the dedicated CPU instructions are also wrapped inside `soc/cpu_ll.h` as helper inline functions.
.. note::
Writing assembly code in application could make your code hard to port between targets, because those customized instructions are not guaranteed to remain the same format on different targets.
.. only:: SOC_DEDIC_GPIO_HAS_INTERRUPT
@ -115,47 +142,7 @@ GPIO Bundle Operations
// wait for done semaphore
xSemaphoreTake(sem, portMAX_DELAY);
Manipulate GPIOs by Writing Assembly Code
------------------------------------------
For advanced users, they can always manipulate the GPIOs by writing assembly code or invoking CPU Low Level APIs. The usual procedure could be:
1. Allocate a GPIO bundle: :cpp:func:`dedic_gpio_new_bundle`
2. Query the mask occupied by that bundle: :cpp:func:`dedic_gpio_get_out_mask` or/and :cpp:func:`dedic_gpio_get_in_mask`
3. Call CPU LL apis (e.g. `cpu_ll_write_dedic_gpio_mask`) or write assembly code with that mask
4. The fasted way of toggling IO is to use the dedicated "set/clear" instructions:
.. only:: esp32s2 or esp32s3
- Set bits of GPIO: ``set_bit_gpio_out imm[7:0]``
- Clear bits of GPIO: ``clr_bit_gpio_out imm[7:0]``
- Note: Immediate value width depends on the number of dedicated GPIO channels
.. only:: esp32c2 or esp32c3
- Set bits of GPIO: ``csrrsi rd, csr, imm[4:0]``
- Clear bits of GPIO: ``csrrci rd, csr, imm[4:0]``
- Note: Can only control the lowest 4 GPIO channels
.. only:: esp32s2
For details of supported dedicated GPIO instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *IO MUX and GPIO Matrix (GPIO, IO_MUX)* [`PDF <{IDF_TARGET_TRM_EN_URL}#iomuxgpio>`__].
.. only:: esp32s3
For details of supported dedicated GPIO instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *Processor Instruction Extensions (PIE) (to be added later)* [`PDF <{IDF_TARGET_TRM_EN_URL}#pie>`__].
.. only:: esp32c2 or esp32c3
For details of supported dedicated GPIO instructions, please refer to *{IDF_TARGET_NAME} Technical Reference Manual* > *ESP-RISC-V CPU* [`PDF <{IDF_TARGET_TRM_EN_URL}#riscvcpu>`__].
The supported dedicated CPU instructions are also wrapped inside `soc/cpu_ll.h` as helper inline functions.
.. note::
Writing assembly code in application could make your code hard to port between targets, because those customized instructions are not guaranteed to remain the same format on different targets.
.. only:: esp32s2
.. only:: SOC_DEDIC_GPIO_HAS_INTERRUPT
Application Example
-------------------