|
Contiki 3.x
|
Implementation of the clock module for the cc2538. More...
Files | |
| file | clock.c |
| Clock driver implementation for the TI cc2538. | |
Functions | |
| void | clock_init (void) |
| Arch-specific implementation of clock_init for the cc2538. More... | |
| CCIF clock_time_t | clock_time (void) |
| Get the current clock time. More... | |
| void | clock_set_seconds (unsigned long sec) |
| Set the value of the platform seconds. More... | |
| CCIF unsigned long | clock_seconds (void) |
| Get the current value of the platform seconds. More... | |
| void | clock_wait (clock_time_t i) |
| Wait for a given number of ticks. More... | |
| void | clock_delay_usec (uint16_t len) |
| Arch-specific implementation of clock_delay_usec for the cc2538. More... | |
| void | clock_delay (unsigned int i) |
| Obsolete delay function but we implement it here since some code still uses it. | |
| void | clock_adjust (void) |
| Adjust the clock following missed SysTick ISRs. More... | |
| void | clock_isr (void) |
| The clock Interrupt Service Routine. More... | |
Implementation of the clock module for the cc2538.
To implement the clock functionality, we use the SysTick peripheral on the cortex-M3. We run the system clock at 16 MHz and we set the SysTick to give us 128 interrupts / sec. However, the Sleep Timer counter value is used for the number of elapsed ticks in order to avoid a significant time drift caused by PM1/2. Contrary to the Sleep Timer, the SysTick peripheral is indeed frozen during PM1/2, so adjusting upon wake-up a tick counter based on this peripheral would hardly be accurate.
| void clock_adjust | ( | void | ) |
Adjust the clock following missed SysTick ISRs.
This function is useful when coming out of PM1/2, during which the system clock is stopped. We adjust the clock counters like after any SysTick ISR.
| void clock_delay_usec | ( | uint16_t | len | ) |
Arch-specific implementation of clock_delay_usec for the cc2538.
Delay a given number of microseconds.
| len | Delay len uSecs |
See clock_init() for GPT0 Timer A's configuration
Definition at line 146 of file clock.c.
References GPT_0_BASE, GPTIMER_CTL, GPTIMER_CTL_TAEN, and GPTIMER_TAILR.
| void clock_init | ( | void | ) |
Arch-specific implementation of clock_init for the cc2538.
Initialize the clock library.
We initialise the SysTick to fire 128 interrupts per second, giving us a value of 128 for CLOCK_SECOND
We also initialise GPT0:Timer A, which is used by clock_delay_usec(). We use 16-bit range (individual), count-down, one-shot, no interrupts. The system clock is at 16MHz giving us 62.5 nano sec ticks for Timer A. Prescaled by 16 gives us a very convenient 1 tick per usec
Definition at line 81 of file clock.c.
References GPT_0_BASE, GPTIMER_CFG, GPTIMER_CTL, GPTIMER_TAMR, GPTIMER_TAPR, SYS_CTRL_RCGCGPT, and SYS_CTRL_RCGCGPT_GPT0.
| void clock_isr | ( | void | ) |
| CCIF unsigned long clock_seconds | ( | void | ) |
Get the current value of the platform seconds.
This could be the number of seconds since startup, or since a standard epoch.
Get the current value of the platform seconds.
The comparison avoids the need to disable clock interrupts for an atomic read of the four-byte variable.
| void clock_set_seconds | ( | unsigned long | sec | ) |
| CCIF clock_time_t clock_time | ( | void | ) |
Get the current clock time.
This function returns the current system clock time.
Get the current clock time.
When 16 bit it typically wraps every 10 minutes. The comparison avoids the need to disable clock interrupts for an atomic read of the multi-byte variable.
| void clock_wait | ( | clock_time_t | i | ) |
Wait for a given number of ticks.
| t | How many ticks. |
Wait for a given number of ticks.
Definition at line 131 of file clock.c.
References clock_time().
1.8.5