diff --git a/configs/sama5d3-xplained/README.txt b/configs/sama5d3-xplained/README.txt index 4b51cbc4de3..3faf04e0fb9 100644 --- a/configs/sama5d3-xplained/README.txt +++ b/configs/sama5d3-xplained/README.txt @@ -2332,6 +2332,8 @@ TRNG and /dev/random Tickless OS =========== + Background + ---------- By default, a NuttX configuration uses a periodic timer interrupt that drives all system timing. The timer is provided by architecture-specifi code that calls into NuttX at a rate controlled by CONFIG_USEC_PER_TICK. @@ -2368,6 +2370,8 @@ Tickless OS OS event will occur, program the interval time and wait for it to fire. When the interval time fires, then the scheduled activity is performed. + Configuration + ------------- The following configuration options will enable support for the Tickless OS for the SAMA5D platforms using TC0 channels 0-3 (other timers or timer channels could be used making the obvious substitutions): @@ -2385,6 +2389,25 @@ Tickless OS CONFIG_SAMA5_TICKLESS_FREERUN=1 : Selects TC0 channel 1 for the free- : running timer + SAMA5 Timer Usage + ----------------- + This current implementation uses two timers: A one-shot timer to + provide the timed events and a free running timer to provide the current + time. Since timers are a limited resource, that could be an issue on + some systems. + + We could do the job with a single timer if we were to keep the single + timer in a free-running at all times. The SAMA5 timer/counters have + 32-bit counters with the capability to generate a compare interrupt when + the timer matches a compare value but also to continue counting without + stopping (giving another, different interrupt when the timer rolls over + from 0xffffffff to zero). So we could potentially just set the compare + at the number of ticks you want PLUS the current value of timer. Then + you could have both with a single timer: An interval timer and a free- + running counter with the same timer! + + Patches are welcome! + I2S Audio Support ================= diff --git a/configs/sama5d3x-ek/README.txt b/configs/sama5d3x-ek/README.txt index 265bc7d3680..9cc88abdf9a 100644 --- a/configs/sama5d3x-ek/README.txt +++ b/configs/sama5d3x-ek/README.txt @@ -2648,6 +2648,8 @@ Touchscreen Testing Tickless OS =========== + Background + ---------- By default, a NuttX configuration uses a periodic timer interrupt that drives all system timing. The timer is provided by architecture-specifi code that calls into NuttX at a rate controlled by CONFIG_USEC_PER_TICK. @@ -2684,6 +2686,8 @@ Tickless OS OS event will occur, program the interval time and wait for it to fire. When the interval time fires, then the scheduled activity is performed. + Configuration + ------------- The following configuration options will enable support for the Tickless OS for the SAMA5D platforms using TC0 channels 0-3 (other timers or timer channels could be used making the obvious substitutions): @@ -2701,6 +2705,25 @@ Tickless OS CONFIG_SAMA5_TICKLESS_FREERUN=1 : Selects TC0 channel 1 for the free- : running timer + SAMA5 Timer Usage + ----------------- + This current implementation uses two timers: A one-shot timer to + provide the timed events and a free running timer to provide the current + time. Since timers are a limited resource, that could be an issue on + some systems. + + We could do the job with a single timer if we were to keep the single + timer in a free-running at all times. The SAMA5 timer/counters have + 32-bit counters with the capability to generate a compare interrupt when + the timer matches a compare value but also to continue counting without + stopping (giving another, different interrupt when the timer rolls over + from 0xffffffff to zero). So we could potentially just set the compare + at the number of ticks you want PLUS the current value of timer. Then + you could have both with a single timer: An interval timer and a free- + running counter with the same timer! + + Patches are welcome! + OV2640 Camera Interface ======================= diff --git a/configs/sama5d4-ek/README.txt b/configs/sama5d4-ek/README.txt index 7d0cb70ba09..a2c81e53c5c 100644 --- a/configs/sama5d4-ek/README.txt +++ b/configs/sama5d4-ek/README.txt @@ -3112,6 +3112,8 @@ TM7000 LCD/Touchscreen Tickless OS =========== + Background + ---------- By default, a NuttX configuration uses a periodic timer interrupt that drives all system timing. The timer is provided by architecture-specifi code that calls into NuttX at a rate controlled by CONFIG_USEC_PER_TICK. @@ -3148,6 +3150,8 @@ Tickless OS OS event will occur, program the interval time and wait for it to fire. When the interval time fires, then the scheduled activity is performed. + Configuration + ------------- The following configuration options will enable support for the Tickless OS for the SAMA5D platforms using TC0 channels 0-3 (other timers or timer channels could be used making the obvious substitutions): @@ -3165,6 +3169,25 @@ Tickless OS CONFIG_SAMA5_TICKLESS_FREERUN=1 : Selects TC0 channel 1 for the free- : running timer + SAMA5 Timer Usage + ----------------- + This current implementation uses two timers: A one-shot timer to + provide the timed events and a free running timer to provide the current + time. Since timers are a limited resource, that could be an issue on + some systems. + + We could do the job with a single timer if we were to keep the single + timer in a free-running at all times. The SAMA5 timer/counters have + 32-bit counters with the capability to generate a compare interrupt when + the timer matches a compare value but also to continue counting without + stopping (giving another, different interrupt when the timer rolls over + from 0xffffffff to zero). So we could potentially just set the compare + at the number of ticks you want PLUS the current value of timer. Then + you could have both with a single timer: An interval timer and a free- + running counter with the same timer! + + Patches are welcome! + SAMA4D4-EK Configuration Options =================================