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esp8266/modmachine: Use common machine_time_pulse_us implementation.

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Testing shows that for frequencies which the esp8266 can handle -- up to
about 1kHz -- `machine.time_pulse_us()` now gives more accurate results.

Prior to this commit it would measure on average about 1us lower, but now
the average is much closer to the true value.  For example a pulse that is
1000us long, it would measure between 998 and 1000us.  Now it measures
between 999us and 1001us.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George
2025-05-23 12:57:20 +10:00
parent ef21ade602
commit 398da22492
3 changed files with 10 additions and 31 deletions
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2
extmod/machine_pulse.c
View File

@@ -30,7 +30,7 @@
#if MICROPY_PY_MACHINE_PULSE
MP_WEAK mp_uint_t machine_time_pulse_us(mp_hal_pin_obj_t pin, int pulse_level, mp_uint_t timeout_us) {
mp_uint_t machine_time_pulse_us(mp_hal_pin_obj_t pin, int pulse_level, mp_uint_t timeout_us) {
mp_uint_t nchanges = 2;
mp_uint_t start = mp_hal_ticks_us();
for (;;) {

9
ports/esp8266/esp_mphal.h
View File

@@ -27,11 +27,20 @@
#include "user_interface.h"
#include "py/ringbuf.h"
#include "shared/runtime/interrupt_char.h"
#include "ets_alt_task.h"
#include "xtirq.h"
#define MICROPY_BEGIN_ATOMIC_SECTION() esp_disable_irq()
#define MICROPY_END_ATOMIC_SECTION(state) esp_enable_irq(state)
// During machine.time_pulse_us, feed WDT every now and then.
#define MICROPY_PY_MACHINE_TIME_PULSE_US_HOOK(dt) \
do { \
if ((dt & 0xffff) == 0xffff && !ets_loop_dont_feed_sw_wdt) { \
system_soft_wdt_feed(); \
} \
} while (0)
void mp_sched_keyboard_interrupt(void);
struct _mp_print_t;

30
ports/esp8266/modmachine.c
View File

@@ -33,7 +33,6 @@
#include "os_type.h"
#include "osapi.h"
#include "etshal.h"
#include "ets_alt_task.h"
#include "user_interface.h"
// #define MACHINE_WAKE_IDLE (0x01)
@@ -327,32 +326,3 @@ MP_DEFINE_CONST_OBJ_TYPE(
print, esp_timer_print,
locals_dict, &esp_timer_locals_dict
);
// Custom version of this function that feeds system WDT if necessary
mp_uint_t machine_time_pulse_us(mp_hal_pin_obj_t pin, int pulse_level, mp_uint_t timeout_us) {
int nchanges = 2;
uint32_t start = system_get_time(); // in microseconds
for (;;) {
uint32_t dt = system_get_time() - start;
// Check if pin changed to wanted value
if (mp_hal_pin_read(pin) == pulse_level) {
if (--nchanges == 0) {
return dt;
}
pulse_level = 1 - pulse_level;
start = system_get_time();
continue;
}
// Check for timeout
if (dt >= timeout_us) {
return (mp_uint_t)-nchanges;
}
// Only feed WDT every now and then, to make sure edge timing is accurate
if ((dt & 0xffff) == 0xffff && !ets_loop_dont_feed_sw_wdt) {
system_soft_wdt_feed();
}
}
}