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95 lines
4.0 KiB
Lua
95 lines
4.0 KiB
Lua
-- eLua reference manual - tmr module
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data_en =
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{
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-- Title
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title = "eLua reference manual - tmr module",
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-- Menu name
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menu_name = "tmr",
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-- Overview
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overview = [[This module contains functions for accessing the hardware timers of the eLua CPU. In addition, if virtual timers are enabled
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(see @arch_platform_timers.html#virtual_timers@here@ and @building.html@here@ for details), they can be used just like the "regular" (hardware)
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timers with a single exception: you can't set the clock of a virtual timer (using @#tmr.setclock@tmr.setclock@). To use virtual timers with this
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module, specify $tmr.VIRTx$ as the timer ID instead of a number. For example, if the eLua image was configured to support 4 virtual timers, they will
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be available by using $tmr.VIRT0$ to $tmr.VIRT3$ as timer IDs.</p>
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<p>All "time units" (delays, differences in time) in this module, as well as in other parts of eLua (timeouts) are expressed in microseconds. However,
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please keep in mind that the actual timer resolution depends on many factors. For example, it's very likely that the @#tmr.delay@tmr.delay@ function won't
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be able to delay for the exact amount you specify (in us), as the real delay depends ona number of variables, most notably the base clock of the timer
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and the size of the timer counter register (32 bits on some platforms, 16 bits on most platforms, other values are less common). To ensure that the delay
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you're requesting is achievable, use @#tmr.getmindelay@tmr.getmindelay@ and @#tmr.getmaxdelay@tmr.getmaxdelay@ to obtain the maximum and the minimum
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achievable wait times on your timer, respectively. Even if your delay is within these limits, the $precision$ of this function still varies a lot,
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mainly as a function of the timer base clock.]],
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-- Functions
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funcs =
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{
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{ sig = "#tmr.delay#( id, period )",
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desc = "Waits for the specified period, then returns.",
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args =
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{
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"$period$ - the timer ID.",
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"$period$ - how long to wait (in us)."
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}
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},
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{ sig = "counter = #tmr.read#( id )",
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desc= "Reads the timer counter register.",
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args = "$id$ - the timer ID.",
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ret = "The value of the timer counter register."
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},
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{ sig = "counter = #tmr.start#( id )",
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desc = "Starts the specified timer.",
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args = "$id$ - the timer ID.",
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ret = "The value of the timer counter register when the timer started.",
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},
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{ sig = "delta = #tmr.gettimediff#( id, counter1, counter2 )",
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desc = "Computes the time difference between two timer counter values (you can get counter values by calling @#tmr.read@tmr.read@ or @#tmr.start@tmr.start@).",
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args =
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{
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"$id$ - the timer ID.",
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"$counter1$ - the first counter value.",
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"$counter2$ - the second counter value.",
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},
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ret = "The time difference (in us)."
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},
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{ sig = "mindelay = #tmr.getmindelay#( id )",
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desc = "Get the minimum achieavable delay on the specified timer.",
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args = "$id$ - the timer ID.",
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ret = "The minimum achievable delay on the specified timer (in us)."
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},
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{ sig = "maxdelay = #tmr.getmaxdelay#( id )",
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desc = "Get the maximum achieavable delay on the specified timer.",
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args = "$id$ - the timer ID.",
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ret = "The maximum achievable delay on the specified timer (in us)."
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},
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{ sig = "clock = #tmr.setclock#( id, clock )",
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desc = "Set the timer clock (the clock used to increment the timer counter register).",
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args =
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{
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"$id$ - the timer ID.",
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"$clock$ - the timer clock (in Hz)."
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},
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ret = [[The actual clock set on the timer (in Hz). Depending on the hardware, this might have a different value than the $clock$ argument.
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$NOTE:$ this function does not work with virtual timers.]]
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},
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{ sig = "clock = #tmr.getclock#( id )",
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desc = "Get the timer clock (the clock used to increment the timer counter register).",
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args = "$id$ - the timer ID.",
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ret = "The timer clock (in Hz)."
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}
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}
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}
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data_pt = data_en
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