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Merge branch 'bugfix/select_rtc_slow_clk' into 'master'

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esp32/clk: Fix starting rtc oscillator if it bad

See merge request idf/esp-idf!2215
This commit is contained in:
Angus Gratton
2018-05-15 12:57:22 +08:00
parent c522f44276 9ad0760b9d
commit 662fe55996
3 changed files with 139 additions and 30 deletions
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36
components/esp32/clk.c
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@@ -36,7 +36,6 @@
* Larger values increase startup delay. Smaller values may cause false positive
* detection (i.e. oscillator runs for a few cycles and then stops).
*/
#define XTAL_32K_DETECT_CYCLES 32
#define SLOW_CLK_CAL_CYCLES CONFIG_ESP32_RTC_CLK_CAL_CYCLES
#define MHZ (1000000)
@@ -128,6 +127,9 @@ void IRAM_ATTR ets_update_cpu_frequency(uint32_t ticks_per_us)
static void select_rtc_slow_clk(rtc_slow_freq_t slow_clk)
{
uint32_t cal_val = 0;
uint32_t wait = 0;
const uint32_t warning_timeout = 3 /* sec */ * 32768 /* Hz */ / (2 * SLOW_CLK_CAL_CYCLES);
bool changing_clock_to_150k = false;
do {
if (slow_clk == RTC_SLOW_FREQ_32K_XTAL) {
/* 32k XTAL oscillator needs to be enabled and running before it can
@@ -137,24 +139,23 @@ static void select_rtc_slow_clk(rtc_slow_freq_t slow_clk)
* oscillator cycles. If the 32k XTAL has not started up, calibration
* will time out, returning 0.
*/
uint32_t wait = 0;
// increment of 'wait' counter equivalent to 3 seconds
const uint32_t warning_timeout = 3 /* sec */ * 32768 /* Hz */ / (2 * XTAL_32K_DETECT_CYCLES);
ESP_EARLY_LOGD(TAG, "waiting for 32k oscillator to start up");
do {
++wait;
rtc_clk_32k_enable(true);
cal_val = rtc_clk_cal(RTC_CAL_32K_XTAL, XTAL_32K_DETECT_CYCLES);
if (wait % warning_timeout == 0) {
ESP_EARLY_LOGW(TAG, "still waiting for 32k oscillator to start up");
}
if(cal_val == 0){
rtc_clk_32k_enable(false);
rtc_clk_32k_bootstrap(CONFIG_ESP32_RTC_XTAL_BOOTSTRAP_CYCLES);
}
} while (cal_val == 0);
rtc_clk_32k_enable(true);
cal_val = rtc_clk_cal(RTC_CAL_32K_XTAL, SLOW_CLK_CAL_CYCLES);
if(cal_val == 0 || cal_val < 15000000L){
ESP_EARLY_LOGE(TAG, "RTC: Not found External 32 kHz XTAL. Switching to Internal 150 kHz RC chain");
slow_clk = RTC_SLOW_FREQ_RTC;
changing_clock_to_150k = true;
}
}
rtc_clk_slow_freq_set(slow_clk);
if (changing_clock_to_150k == true && wait > 1){
// This helps when there are errors when switching the clock from External 32 kHz XTAL to Internal 150 kHz RC chain.
rtc_clk_32k_enable(false);
uint32_t min_bootstrap = 5; // Min bootstrapping for continue switching the clock.
rtc_clk_32k_bootstrap(min_bootstrap);
rtc_clk_32k_enable(true);
}
if (SLOW_CLK_CAL_CYCLES > 0) {
/* TODO: 32k XTAL oscillator has some frequency drift at startup.
@@ -165,6 +166,9 @@ static void select_rtc_slow_clk(rtc_slow_freq_t slow_clk)
const uint64_t cal_dividend = (1ULL << RTC_CLK_CAL_FRACT) * 1000000ULL;
cal_val = (uint32_t) (cal_dividend / rtc_clk_slow_freq_get_hz());
}
if (++wait % warning_timeout == 0) {
ESP_EARLY_LOGW(TAG, "still waiting for source selection RTC");
}
} while (cal_val == 0);
ESP_EARLY_LOGD(TAG, "RTC_SLOW_CLK calibration value: %d", cal_val);
esp_clk_slowclk_cal_set(cal_val);