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SourceVuESP-IDF Framework and ExamplesESP-IDFi2c_filter_enable()

i2c_filter_enable() function

Enable hardware filter on I2C bus Sometimes the I2C bus is disturbed by high frequency noise(about 20ns), or the rising edge of the SCL clock is very slow, these may cause the master state machine to break. Enable hardware filter can filter out high frequency interference and make the master more stable.

Syntax

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Summary

Declaration

Definition

esp_err_t i2c_filter_enable(i2c_port_t i2c_num, uint8_t cyc_num);

Implemented in i2c.c:861

Arguments

Argument

Description

i2c_num

I2C port number to filter

cyc_num

the APB cycles need to be filtered (0<= cyc_num <=7). When the period of a pulse is less than cyc_num * APB_cycle, the I2C controller will ignore this pulse.

Return value

- ESP_OK Success - ESP_ERR_INVALID_ARG Parameter error

Notes

Enable filter will slow down the SCL clock.

References

Code

Location

esp_err_t i2c_filter_enable(i2c_port_t i2c_num, uint8_t cyc_num)

esp_err_t i2c_filter_enable(i2c_port_t i2c_num, uint8_t cyc_num);

Call Tree

i2c_filter_enable() calls 6 functions:

i2c_filter_enable()

vPortEnterCritical()

esp_log_timestamp()

esp_log_write()

vPortExitCritical()

i2c_ll_master_set_filter()

i2c_ll_update()

Data Use

i2c_filter_enable() reads 12 variables:

esp_log_level_t::ESP_LOG_ERROR

esp_log_level_t::ESP_LOG_WARN

esp_log_level_t::ESP_LOG_INFO

esp_log_level_t::ESP_LOG_DEBUG

esp_log_level_t::ESP_LOG_VERBOSE

i2c_port_t::I2C_NUM_MAX

i2c_hal_context_t::dev

i2c_context_t::hal

i2c_context_t::spinlock

i2c_filter_enable()

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Lifecycle

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