Commit Graph

6 Commits

Author SHA1 Message Date
Ivan Grokhotkov
5b54ae76d4 esp_timer, hal: add support for non-integer systimer frequency
When ESP32-C2 is paired with a 26 MHz XTAL, the systimer tick
frequency becomes equal to 26 / 2.5 = 10.4 MHz. Previously we always
assumed that systimer tick frequency is integer (and 1 MHz * power of
two, above that!).
This commit introduces a new LL macro, SYSTIMER_LL_TICKS_PER_US_DIV.
It should be set in such a way that:

1. SYSTIMER_LL_TICKS_PER_US / SYSTIMER_LL_TICKS_PER_US_DIV equals the
   actual systimer tick frequency,
2. and SYSTIMER_LL_TICKS_PER_US is integer.

For ESP32-C2 this means that SYSTIMER_LL_TICKS_PER_US = 52 and
SYSTIMER_LL_TICKS_PER_US_DIV = 5.

This introduced two possible issues:

1. Overflow when multiplying systimer counter by 5
   - Should not be an issue, since systimer counter is 52-bit, so
     counter * 5 is no more than 55-bit.
2. The code needs to perform:
   - divide by 5: when converting from microseconds to ticks
   - divide by 52: when converting from ticks to microseconds
   The latter potentially introduces a performance issue for the
   esp_timer_get_time function.
2022-07-11 12:24:37 +08:00
wuzhenghui
17b3d139d5 hal: use systimer HAL IMPL in ESP32C2 ROM 2022-05-05 17:41:11 +08:00
Cao Sen Miao
09487761cf ESP8684: add freertos, hal, esp_system support 2021-11-06 17:33:44 +08:00
morris
9afdf54748 hal: added HAL_ASSERT 2021-06-22 11:28:01 +08:00
morris
988c88a6b1 systimer: optimise esp_timer_get_time 2021-04-26 11:54:02 +08:00
morris
ec898b771e systimer: strip hal driver 2021-04-22 21:08:39 +08:00