FreeCalypso > hg > freecalypso-tools
view target-utils/buzplayer/timer.c @ 404:c0716b2ddfce
CHANGES: fc-host-tools-r8 is out
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Sun, 18 Mar 2018 18:40:41 +0000 |
parents | e3d40f49d8c4 |
children |
line wrap: on
line source
/* * 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" void timer_init() { TIMER1_REGS.cntl = CNTL_CLOCK_ENABLE; TIMER1_REGS.load = 1875; TIMER1_REGS.cntl = CNTL_CLOCK_ENABLE | CNTL_AUTO_RELOAD | CNTL_START; } void wait_for_tdma_frame() { u16 read1, read2; read1 = TIMER1_REGS.read; for (;;) { read2 = TIMER1_REGS.read; if (read2 > read1) return; read1 = read2; } }