File syn_port_hpclock.h¶

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High-precision clock port interface — implement for your platform. More...

#include <stdint.h>

Public Attributes¶

Type	Name
volatile uint32_t	syn_hpclock_msb Global overflow counter — incremented by the platform ISR.

Public Functions¶

Type	Name
uint32_t	syn_port_hpclock_freq_hz (void) Return the timer clock frequency in Hz.
volatile uint32_t *	syn_port_hpclock_lsb_ptr (void) Return a pointer to the hardware timer count register.

Macros¶

Type	Name
define	SYN_HPCLOCK_OVERFLOW_TICK () `([syn\_hpclock\_msb](syn__hpclock_8c.md#variable-syn_hpclock_msb)++)` Macro for the platform overflow ISR — one line, nothing else.

Detailed Description¶

Provides the hardware timer counter register and overflow counter that the syn_hpclock driver uses to construct 64-bit system-clock- precision timestamps.

Platform implementation checklist¶

Configure a free-running hardware timer at the system clock rate (or as fast as practical). For example, STM32 TIM2 in free-run mode, or AVR Timer1 with no prescaler.
Define syn_port_hpclock_lsb_ptr() to return a pointer to the timer's count register.
Enable the timer overflow interrupt and call SYN_HPCLOCK_OVERFLOW_TICK() from the ISR.
Define syn_port_hpclock_freq_hz() to return the timer's clock frequency.
The overflow ISR MUST have the highest interrupt priority in the system. The resolve algorithm assumes the overflow ISR can preempt any context that calls SYN_HPCLOCK_CAPTURE(). If a higher-priority ISR captures a timestamp while the overflow ISR is pended, the resolved tick will be silently wrong by one full counter period. There is no runtime detection of this error.

** **

// In your platform port file:
volatile uint32_t *syn_port_hpclock_lsb_ptr(void) {
    return &TIM2->CNT;
}

uint32_t syn_port_hpclock_freq_hz(void) {
    return 84000000UL;
}

// Priority 0 = highest on Cortex-M NVIC
void TIM2_IRQHandler(void) {
    SYN_HPCLOCK_OVERFLOW_TICK();
    LL_TIM_ClearFlag_UPDATE(TIM2);
}

Public Attributes Documentation¶

variable syn_hpclock_msb¶

Global overflow counter — incremented by the platform ISR.

volatile uint32_t syn_hpclock_msb;

Declared here so both the port ISR and the driver can access it. Defined in syn_hpclock.c.

Public Functions Documentation¶

function syn_port_hpclock_freq_hz¶

Return the timer clock frequency in Hz.

uint32_t syn_port_hpclock_freq_hz (
    void
)

Used for tick-to-nanosecond conversion. Must be a compile-time constant or a value that does not change after initialization.

Returns:

Timer frequency in Hz (e.g. 16000000 for 16 MHz).

function syn_port_hpclock_lsb_ptr¶

Return a pointer to the hardware timer count register.

volatile uint32_t * syn_port_hpclock_lsb_ptr (
    void
)

The returned pointer must be volatile and point to a memory-mapped register that increments at the rate returned by syn_port_hpclock_freq_hz().

Returns:

Pointer to the timer counter register.

Macro Definition Documentation¶

define SYN_HPCLOCK_OVERFLOW_TICK¶

Macro for the platform overflow ISR — one line, nothing else.

#define SYN_HPCLOCK_OVERFLOW_TICK (

) `( syn_hpclock_msb ++)`

Call this from your timer update/overflow interrupt handler. Do not add any other logic before this macro in the ISR.

The documentation for this class was generated from the following file src/syntropic/port/syn_port_hpclock.h