eb00b4e2e9
Change timer from counting to a specified value and stopping or
free running, to always be free running. But now the timer sets
a reached flag when the target number of ticks has been
reached.
Signed-off-by: Joachim Strömbergson <joachim@assured.se>
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| README.md | ||
timer
Timer with prescaler and support for free running mode.
Introduction
This core implements a simple timer with a prescaler and support for a free running mode.
The prescaler allows measurement of time durations rather than cycles. If for example setting the prescaler to the clock frequency in Hertz, the timer will count seconds. After (prescaler * timer) number of cycles the timer will stop. Checking status of the timer can be done by reading the STATUS_RUNNING_BIT. If set to zero, the timer has completed.
If the free running mode is set (default off), the counter will not stpp when the number of cycles defined by (prescaler * timer) has been reached. Instead the timer continues until the CTRL_STOP_BIT is asserted.
API
The following addresses define the API for the timer:
ADDR_CTRL: 0x08
CTRL_START_BIT: 0
CTRL_STOP_BIT: 1
ADDR_STATUS: 0x09
STATUS_RUNNING_BIT: 0
ADDR_PRESCALER: 0x0a
ADDR_TIMER: 0x0b
ADDR_FREE_RUNNING: 0x0c
FREE_RUNNING_BIT 0
ADDR_PRESCALER and ADDR_TIMER registers should be set to a non-negative value. Default values for the these registers are one (1). Note that these registers can't be changed when the timer is running.