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soc/rtc: warn if detected XTAL frequency does not match configured one

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Since 9a8c0392, XTAL frequency is set to 40MHz by default, and users
of 26MHz boards need to select 26MHz manually. Most users are not aware
of this change, and existing getting started guides do not mention that
XTAL frequency needs to be set for some boards. So users are left with
garbage output from UART without any clue what to check.

This change adds a warning in case specific XTAL frequency was set, and
it does not match automatically detected one. This should help users
fix the issue.
This commit is contained in:
Ivan Grokhotkov 2017-09-11 11:42:26 +08:00
parent 050ae50e83
commit 5a88f90a33
3 changed files with 14 additions and 3 deletions
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1
components/bootloader/subproject/main/bootloader_start.c
View File

@ -753,7 +753,6 @@ static void clock_configure(void)
cpu_freq = RTC_CPU_FREQ_240M;
}
uart_tx_wait_idle(0);
rtc_clk_config_t clk_cfg = RTC_CLK_CONFIG_DEFAULT();
clk_cfg.xtal_freq = CONFIG_ESP32_XTAL_FREQ;
clk_cfg.cpu_freq = cpu_freq;

13
components/soc/esp32/rtc_clk.c
View File

@ -541,7 +541,8 @@ void rtc_clk_init(rtc_clk_config_t cfg)
SET_PERI_REG_BITS(ANA_CONFIG_REG, ANA_CONFIG_M, ANA_CONFIG_M, ANA_CONFIG_S);
CLEAR_PERI_REG_MASK(ANA_CONFIG_REG, I2C_APLL_M | I2C_BBPLL_M);
/* Estimate XTAL frequency if requested */
/* Estimate XTAL frequency */
rtc_xtal_freq_t est_xtal_freq = rtc_clk_xtal_freq_estimate();
rtc_xtal_freq_t xtal_freq = cfg.xtal_freq;
if (xtal_freq == RTC_XTAL_FREQ_AUTO) {
if (clk_val_is_valid(READ_PERI_REG(RTC_XTAL_FREQ_REG))) {
@ -549,13 +550,21 @@ void rtc_clk_init(rtc_clk_config_t cfg)
xtal_freq = rtc_clk_xtal_freq_get();
} else {
/* Not set yet, estimate XTAL frequency based on RTC_FAST_CLK */
xtal_freq = rtc_clk_xtal_freq_estimate();
xtal_freq = est_xtal_freq;
if (xtal_freq == RTC_XTAL_FREQ_AUTO) {
SOC_LOGW(TAG, "Can't estimate XTAL frequency, assuming 26MHz");
xtal_freq = RTC_XTAL_FREQ_26M;
}
}
} else if (!clk_val_is_valid(READ_PERI_REG(RTC_XTAL_FREQ_REG))) {
/* Exact frequency was set in sdkconfig, but still warn if autodetected
* frequency is different. If autodetection failed, worst case we get a
* bit of garbage output.
*/
SOC_LOGW(TAG, "Possibly invalid CONFIG_ESP32_XTAL_FREQ setting (%dMHz). Detected %d MHz.",
xtal_freq, est_xtal_freq);
}
uart_tx_wait_idle(0);
rtc_clk_xtal_freq_update(xtal_freq);
rtc_clk_apb_freq_update(xtal_freq * MHZ);
/* Set CPU frequency */

3
docs/get-started/index.rst
View File

@ -205,6 +205,9 @@ Here are couple of tips on navigation and use of ``menuconfig``:
If you are **Arch Linux** user, navigate to ``SDK tool configuration`` and change the name of ``Python 2 interpreter`` from ``python`` to ``python2``.
.. note::
Most ESP32 development boards have a 40MHz crystal installed. However, some boards use a 26MHz crystal. If your board uses a 26MHz crystal, or you get garbage output from serial port after code upload, adjust the :ref:`CONFIG_ESP32_XTAL_FREQ` option in menuconfig.
.. _get-started-build-flash: