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

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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/*
 * FreeCalypso buzzer "melodies" have times measured in TDMA frames,
 * as that is the time unit in the main firmware which will ultimately
 * play them.  In this standalone buzzer player we simulate TDMA frame
 * timing by programming Calypso TIMER1 with the period of 1875, and
 * we detect timer overflow (one virtual TDMA frame time having passed)
 * by polling the read register to avoid the need for interrupt handling
 * infrastructure.
 */

#include "types.h"
#include "timer.h"

timer_init()
{
	TIMER1_REGS.cntl = CNTL_CLOCK_ENABLE;
	TIMER1_REGS.load = 1875;
	TIMER1_REGS.cntl = CNTL_CLOCK_ENABLE | CNTL_AUTO_RELOAD | CNTL_START;
}