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rmt: support REF_TICK as channel clock source

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Closes https://github.com/espressif/esp-idf/pull/3952
This commit is contained in:
morris
2020-02-14 14:33:07 +08:00
parent 3c43264f83
commit 0e4d82bc55
7 changed files with 82 additions and 42 deletions
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6
docs/en/api-reference/peripherals/rmt.rst
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@@ -113,7 +113,11 @@ Common Parameters
* The RMT **operation mode** - whether this channel is used to transmit or receive data, selected by setting a **rmt_mode** members to one of the values from :cpp:type:`rmt_mode_t`.
* What is the **pin number** to transmit or receive RMT signals, selected by setting **gpio_num**.
* How many **memory blocks** will be used by the channel, set with **mem_block_num**.
* A **clock divider**, that will determine the range of pulse length generated by the RMT transmitter or discriminated by the receiver. Selected by setting **clk_div** to a value within [1 .. 255] range. The RMT source clock is typically APB CLK, 80Mhz by default.
* Extra miscellaneous parameters for the channel can be set in the **flags**.
* When **RMT_CHANNEL_FLAGS_ALWAYS_ON** is set, RMT channel will take REF_TICK as source clock. The benefit is, RMT channel can continue work even when APB clock is changing. See :doc:`power_management <../system/power_management>` for more information.
* A **clock divider**, that will determine the range of pulse length generated by the RMT transmitter or discriminated by the receiver. Selected by setting **clk_div** to a value within [1 .. 255] range. The RMT source clock is typically APB CLK, 80Mhz by default. But when **RMT_CHANNEL_FLAGS_ALWAYS_ON** is set in **flags**, RMT source clock is changed to REF_TICK.
.. note::

2
docs/en/api-reference/system/power_management.rst
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@@ -77,7 +77,7 @@ The following peripherals work normally even when the APB frequency is changing:
- **UART**: if REF_TICK is used as a clock source. See `use_ref_tick` member of :cpp:class:`uart_config_t`.
- **LEDC**: if REF_TICK is used as a clock source. See :cpp:func:`ledc_timer_config` function.
- **RMT**: if REF_TICK is used as a clock source. Although the driver does not support REF_TICK, this feature can be enabled by clearing the ``RMT_REF_ALWAYS_ON_CHx`` bit for the respective channel.
- **RMT**: if REF_TICK is used as a clock source. See `flags` member of :cpp:class:`rmt_config_t` and macro `RMT_CHANNEL_FLAGS_ALWAYS_ON`.
Currently, the following peripheral drivers are aware of DFS and will use the ``ESP_PM_APB_FREQ_MAX`` lock for the duration of the transaction: