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esp32: add support for 8MD256 and external 32k as slow clock options

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This commit is contained in:
Ivan Grokhotkov
2018-08-13 01:12:01 +03:00
parent 5bf3654637
commit 96971e3e9f
2 changed files with 57 additions and 10 deletions
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44
components/esp32/clk.c
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@@ -40,7 +40,23 @@
#define MHZ (1000000)
static void select_rtc_slow_clk(rtc_slow_freq_t slow_clk);
/* Indicates that this 32k oscillator gets input from external oscillator, rather
* than a crystal.
*/
#define EXT_OSC_FLAG BIT(3)
/* This is almost the same as rtc_slow_freq_t, except that we define
* an extra enum member for the external 32k oscillator.
* For convenience, lower 2 bits should correspond to rtc_slow_freq_t values.
*/
typedef enum {
SLOW_CLK_150K = RTC_SLOW_FREQ_RTC, //!< Internal 150 kHz RC oscillator
SLOW_CLK_32K_XTAL = RTC_SLOW_FREQ_32K_XTAL, //!< External 32 kHz XTAL
SLOW_CLK_8MD256 = RTC_SLOW_FREQ_8MD256, //!< Internal 8 MHz RC oscillator, divided by 256
SLOW_CLK_32K_EXT_OSC = RTC_SLOW_FREQ_32K_XTAL | EXT_OSC_FLAG //!< External 32k oscillator connected to 32K_XP pin
} slow_clk_sel_t;
static void select_rtc_slow_clk(slow_clk_sel_t slow_clk);
// g_ticks_us defined in ROMs for PRO and APP CPU
extern uint32_t g_ticks_per_us_pro;
@@ -71,8 +87,12 @@ void esp_clk_init(void)
rtc_clk_fast_freq_set(RTC_FAST_FREQ_8M);
#ifdef CONFIG_ESP32_RTC_CLOCK_SOURCE_EXTERNAL_CRYSTAL
select_rtc_slow_clk(RTC_SLOW_FREQ_32K_XTAL);
#if defined(CONFIG_ESP32_RTC_CLOCK_SOURCE_EXTERNAL_CRYSTAL)
select_rtc_slow_clk(SLOW_CLK_32K_XTAL);
#elif defined(CONFIG_ESP32_RTC_CLOCK_SOURCE_EXTERNAL_OSC)
select_rtc_slow_clk(SLOW_CLK_32K_EXT_OSC);
#elif defined(CONFIG_ESP32_RTC_CLOCK_SOURCE_INTERNAL_8MD256)
select_rtc_slow_clk(SLOW_CLK_8MD256);
#else
select_rtc_slow_clk(RTC_SLOW_FREQ_RTC);
#endif
@@ -117,12 +137,12 @@ void IRAM_ATTR ets_update_cpu_frequency(uint32_t ticks_per_us)
g_ticks_per_us_app = ticks_per_us;
}
static void select_rtc_slow_clk(rtc_slow_freq_t slow_clk)
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;
uint32_t freq_hz = ((slow_clk == RTC_SLOW_FREQ_32K_XTAL) ? 32768 : 150000);
do {
if (slow_clk == RTC_SLOW_FREQ_32K_XTAL) {
if (rtc_slow_freq == RTC_SLOW_FREQ_32K_XTAL) {
/* 32k XTAL oscillator needs to be enabled and running before it can
* be used. Hardware doesn't have a direct way of checking if the
* oscillator is running. Here we use rtc_clk_cal function to count
@@ -131,17 +151,23 @@ static void select_rtc_slow_clk(rtc_slow_freq_t slow_clk)
* will time out, returning 0.
*/
ESP_EARLY_LOGD(TAG, "waiting for 32k oscillator to start up");
rtc_clk_32k_enable(true);
if (slow_clk == SLOW_CLK_32K_XTAL) {
rtc_clk_32k_enable(true);
} else if (slow_clk == SLOW_CLK_32K_EXT_OSC) {
rtc_clk_32k_enable_external();
}
// 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) {
slow_clk = RTC_SLOW_FREQ_RTC;
ESP_EARLY_LOGW(TAG, "32 kHz XTAL not found, switching to internal 150 kHz oscillator");
rtc_slow_freq = RTC_SLOW_FREQ_RTC;
}
}
} else if (rtc_slow_freq == RTC_SLOW_FREQ_8MD256) {
rtc_clk_8m_enable(true, true);
}
rtc_clk_slow_freq_set(slow_clk);
rtc_clk_slow_freq_set(rtc_slow_freq);
if (SLOW_CLK_CAL_CYCLES > 0) {
/* TODO: 32k XTAL oscillator has some frequency drift at startup.