Comtrol eCos - Manual (Page 334)

Chapter 11. Porting Guide
define -file system.h CYGHWR_MEMORY_LAYOUT_H
calculated { CYG_HAL_STARTUP == "RAM" ? " < pkgconf/mlt_mips_tx39_jmr3904_ram.h > " : \
" < pkgconf/mlt_mips_tx39_jmr3904_rom.h > " }
}
}
Common Target Options
All platforms also specify real-time clock details:
# Real-time clock/counter specifics
cdl_component CYGNUM_HAL_RTC_CONSTANTS {
display "Real-time clock constants."
flavor none
cdl_option CYGNUM_HAL_RTC_NUMERATOR {
display "Real-time clock numerator"
flavor data
calculated 1000000000
}
cdl_option CYGNUM_HAL_RTC_DENOMINATOR {
display "Real-time clock denominator"
flavor data
calculated 100
}
# Isn’t a nice way to handle freq requirement!
cdl_option CYGNUM_HAL_RTC_PERIOD {
display "Real-time clock period"
flavor data
legal_values { 15360 20736 }
calculated { CYGHWR_HAL_MIPS_CPU_FREQ == 50 ? 15360 : \
CYGHWR_HAL_MIPS_CPU_FREQ == 66 ? 20736 : 0 }
}
}
The NUMERATOR divided by the DENOMINATOR gives the number of nanoseconds per tick. The PERIOD is the divider
to be programmed into a hardware timer that is driven from an appropriate hardware clock, such that the timer
overflows once per tick (normally generating a CPU interrupt to mark the end of a tick). The tick default rate is
typically 100Hz.
Platforms that make use of the virtual vector ROM calling interface (see the Section called Virtual Vectors
(eCos/ROM Monitor Calling Interface) ) will also specify details necessary to define configuration channels (these
options are from the SH/EDK7707 HAL) :
cdl_option CYGNUM_HAL_VIRTUAL_VECTOR_COMM_CHANNELS {
display "Number of communication channels on the board"
flavor data
calculated 1
}
cdl_option CYGNUM_HAL_VIRTUAL_VECTOR_DEBUG_CHANNEL {
display "Debug serial port"
flavor data
230