Commit 1f2daf43 authored by danicampora's avatar danicampora
Browse files

cc3200: Correct ticks_cpu and ticks_us functions in time module.

parent 1c7f9b16
...@@ -58,32 +58,14 @@ void sys_tick_wait_at_least(uint32_t start_tick, uint32_t delay_ms) { ...@@ -58,32 +58,14 @@ void sys_tick_wait_at_least(uint32_t start_tick, uint32_t delay_ms) {
// The SysTick timer counts down at HAL_FCPU_HZ, so we can use that knowledge // The SysTick timer counts down at HAL_FCPU_HZ, so we can use that knowledge
// to grab a microsecond counter. // to grab a microsecond counter.
//
// We assume that HAL_GetTick returns milliseconds. // We assume that HAL_GetTick returns milliseconds.
uint32_t sys_tick_get_microseconds(void) { uint32_t sys_tick_get_microseconds(void) {
mp_uint_t irq_state = disable_irq(); mp_uint_t irq_state = disable_irq();
uint32_t counter = SysTickValueGet(); uint32_t counter = SysTickValueGet();
uint32_t milliseconds = HAL_GetTick(); uint32_t milliseconds = HAL_GetTick();
uint32_t status = (HWREG(NVIC_ST_CTRL));
enable_irq(irq_state); enable_irq(irq_state);
// It's still possible for the countflag bit to get set if the counter was uint32_t load = SysTickPeriodGet();
// reloaded between reading VAL and reading CTRL. With interrupts disabled
// it definitely takes less than 50 HCLK cycles between reading VAL and
// reading CTRL, so the test (counter > 50) is to cover the case where VAL
// is +ve and very close to zero, and the COUNTFLAG bit is also set.
if ((status & NVIC_ST_CTRL_COUNT) && counter > 50) {
// This means that the HW reloaded VAL between the time we read VAL and the
// time we read CTRL, which implies that there is an interrupt pending
// to increment the tick counter.
milliseconds++;
}
uint32_t load = (HWREG(NVIC_ST_RELOAD));
counter = load - counter; // Convert from decrementing to incrementing counter = load - counter; // Convert from decrementing to incrementing
return (milliseconds * 1000) + ((counter * 1000) / load);
// ((load + 1) / 1000) is the number of counts per microsecond.
//
// counter / ((load + 1) / 1000) scales from the systick clock to microseconds
// and is the same thing as (counter * 1000) / (load + 1)
return milliseconds * 1000 + (counter * 1000) / (load + 1);
} }
...@@ -150,33 +150,25 @@ STATIC mp_obj_t time_sleep_us (mp_obj_t usec_in) { ...@@ -150,33 +150,25 @@ STATIC mp_obj_t time_sleep_us (mp_obj_t usec_in) {
STATIC MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_us_obj, time_sleep_us); STATIC MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_us_obj, time_sleep_us);
STATIC mp_obj_t time_ticks_ms(void) { STATIC mp_obj_t time_ticks_ms(void) {
// We want to "cast" the 32 bit unsigned into a small-int. This means // We want to "cast" the 32 bit unsigned into a 30-bit small-int
// copying the MSB down 1 bit (extending the sign down), which is
// equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
return MP_OBJ_NEW_SMALL_INT(HAL_GetTick() & MP_SMALL_INT_POSITIVE_MASK); return MP_OBJ_NEW_SMALL_INT(HAL_GetTick() & MP_SMALL_INT_POSITIVE_MASK);
} }
STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_ms_obj, time_ticks_ms); STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_ms_obj, time_ticks_ms);
STATIC mp_obj_t time_ticks_us(void) { STATIC mp_obj_t time_ticks_us(void) {
// We want to "cast" the 32 bit unsigned into a small-int. This means // We want to "cast" the 32 bit unsigned into a 30-bit small-int
// copying the MSB down 1 bit (extending the sign down), which is
// equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
return MP_OBJ_NEW_SMALL_INT(sys_tick_get_microseconds() & MP_SMALL_INT_POSITIVE_MASK); return MP_OBJ_NEW_SMALL_INT(sys_tick_get_microseconds() & MP_SMALL_INT_POSITIVE_MASK);
} }
STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_us_obj, time_ticks_us); STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_us_obj, time_ticks_us);
STATIC mp_obj_t time_ticks_cpu(void) { STATIC mp_obj_t time_ticks_cpu(void) {
// We want to "cast" the 32 bit unsigned into a small-int. This means // We want to "cast" the 32 bit unsigned into a 30-bit small-int
// copying the MSB down 1 bit (extending the sign down), which is return MP_OBJ_NEW_SMALL_INT((SysTickPeriodGet() - SysTickValueGet()) & MP_SMALL_INT_POSITIVE_MASK);
// equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
return MP_OBJ_NEW_SMALL_INT(SysTickValueGet() & MP_SMALL_INT_POSITIVE_MASK);
} }
STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_cpu_obj, time_ticks_cpu); STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_cpu_obj, time_ticks_cpu);
STATIC mp_obj_t time_ticks_diff(mp_obj_t t0, mp_obj_t t1) { STATIC mp_obj_t time_ticks_diff(mp_obj_t t0, mp_obj_t t1) {
// We want to "cast" the 32 bit unsigned into a small-int. This means // We want to "cast" the 32 bit unsigned into a 30-bit small-int
// copying the MSB down 1 bit (extending the sign down), which is
// equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
uint32_t start = mp_obj_get_int(t0); uint32_t start = mp_obj_get_int(t0);
uint32_t end = mp_obj_get_int(t1); uint32_t end = mp_obj_get_int(t1);
return MP_OBJ_NEW_SMALL_INT((end - start) & MP_SMALL_INT_POSITIVE_MASK); return MP_OBJ_NEW_SMALL_INT((end - start) & MP_SMALL_INT_POSITIVE_MASK);
......
...@@ -70,8 +70,6 @@ print(abs(time.ticks_diff(t1, t2)- 50) <= 1) ...@@ -70,8 +70,6 @@ print(abs(time.ticks_diff(t1, t2)- 50) <= 1)
t1 = time.ticks_us() t1 = time.ticks_us()
time.sleep_us(1000) time.sleep_us(1000)
t2 = time.ticks_us() t2 = time.ticks_us()
print(time.ticks_diff(t1, t2) < 2000) print(time.ticks_diff(t1, t2) < 1500)
t1 = time.ticks_cpu() print(time.ticks_diff(time.ticks_cpu(), time.ticks_cpu()) < 16384)
t2 = time.ticks_cpu()
print(time.ticks_diff(t1, t2) >= 0)
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