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annotate target-utils/buzplayer/timer.c @ 77:0f11da299b7d

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buzplayer: beginning of timer implementation
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 27 Oct 2016 04:01:16 +0000
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children e3d40f49d8c4
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77
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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1 /*
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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2 * FreeCalypso buzzer "melodies" have times measured in TDMA frames,
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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3 * as that is the time unit in the main firmware which will ultimately
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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4 * play them. In this standalone buzzer player we simulate TDMA frame
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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5 * timing by programming Calypso TIMER1 with the period of 1875, and
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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6 * we detect timer overflow (one virtual TDMA frame time having passed)
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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7 * by polling the read register to avoid the need for interrupt handling
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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8 * infrastructure.
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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9 */
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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10
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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11 #include "types.h"
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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12 #include "timer.h"
0f11da299b7d buzplayer: beginning of timer implementation
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13
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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14 timer_init()
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Mychaela Falconia <falcon@freecalypso.org>
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15 {
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Mychaela Falconia <falcon@freecalypso.org>
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16 TIMER1_REGS.cntl = CNTL_CLOCK_ENABLE;
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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17 TIMER1_REGS.load = 1875;
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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18 TIMER1_REGS.cntl = CNTL_CLOCK_ENABLE | CNTL_AUTO_RELOAD | CNTL_START;
0f11da299b7d buzplayer: beginning of timer implementation
Mychaela Falconia <falcon@freecalypso.org>
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19 }