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esp32: Add a Kconfig option- Number of attempts to repeat 32k XTAL calibration

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Closes: IDF-1479
This commit is contained in:
KonstantinKondrashov
2020-03-10 19:23:55 +08:00
committed by bot
parent 4fe04f1151
commit a259746016
2 changed files with 30 additions and 1 deletions
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21
components/esp32/clk.c
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@@ -41,8 +41,19 @@
*/
#define SLOW_CLK_CAL_CYCLES CONFIG_ESP32_RTC_CLK_CAL_CYCLES
#ifdef CONFIG_ESP32_RTC_XTAL_CAL_RETRY
#define RTC_XTAL_CAL_RETRY CONFIG_ESP32_RTC_XTAL_CAL_RETRY
#else
#define RTC_XTAL_CAL_RETRY 1
#endif
#define MHZ (1000000)
/* Lower threshold for a reasonably-looking calibration value for a 32k XTAL.
* The ideal value (assuming 32768 Hz frequency) is 1000000/32768*(2**19) = 16*10^6.
*/
#define MIN_32K_XTAL_CAL_VAL 15000000L
/* Indicates that this 32k oscillator gets input from external oscillator, rather
* than a crystal.
*/
@@ -172,6 +183,11 @@ static void select_rtc_slow_clk(slow_clk_sel_t slow_clk)
{
rtc_slow_freq_t rtc_slow_freq = slow_clk & RTC_CNTL_ANA_CLK_RTC_SEL_V;
uint32_t cal_val = 0;
/* number of times to repeat 32k XTAL calibration
* before giving up and switching to the internal RC
*/
int retry_32k_xtal = RTC_XTAL_CAL_RETRY;
do {
if (rtc_slow_freq == RTC_SLOW_FREQ_32K_XTAL) {
/* 32k XTAL oscillator needs to be enabled and running before it can
@@ -190,7 +206,10 @@ static void select_rtc_slow_clk(slow_clk_sel_t slow_clk)
// When SLOW_CLK_CAL_CYCLES is set to 0, clock calibration will not be performed at startup.
if (SLOW_CLK_CAL_CYCLES > 0) {
cal_val = rtc_clk_cal(RTC_CAL_32K_XTAL, SLOW_CLK_CAL_CYCLES);
if (cal_val == 0 || cal_val < 15000000L) {
if (cal_val == 0 || cal_val < MIN_32K_XTAL_CAL_VAL) {
if (retry_32k_xtal-- > 0) {
continue;
}
ESP_EARLY_LOGW(TAG, "32 kHz XTAL not found, switching to internal 150 kHz oscillator");
rtc_slow_freq = RTC_SLOW_FREQ_RTC;
}