SuperH-based fx calculators
fx-CG20, timer

The 7305 extra TMU is similar to the legacy customized system timer's extra TMU (A44C0030)

Address Size (bit) Int pri register System timer 7730 IPR
A44D0030 8 IPRJ h'0FFF 5..10; bit0:startflag -
A44D0034 32   constant  
A44D0038 32   count  
A44D003C 8   bit1:underflowflag;bit0:enableintflag  
A44D0050 8 IPRG h'F0FF 1 SCIF1
A44D0054 32      
A44D0058 32      
A44D005C 8      
A44D0070 8 IPRG h'FF0F 2 SCIF2
A44D0074 32      
A44D0078 32      
A44D007C 8      
A44D0090 8 IPRE h'FF0F 3 -
A44D0094 32      
A44D0098 32      
A44D009C 8      
A44D00B0 8 IPRI h'0FFF 4 SIOF
A44D00B4 32      
A44D00B8 32      
A44D00BC 8      
A44D00D0 8   helping timeout timer  
A44D00D4 32   constant  
A44D00D8 32   count  
A44D00DC 8      

The timer table starts at 0x88090014. The table consists of 10 timer entries each 16 byte long.

Timer 4 serves the USB communication and uses syscall 0x1ECF as handler (Range of InternalTimerID: 1..10).

For the interfaces of syscalls 0x08D9..0x08DC refer to the legacy syscalls 0x0118..0x11B.
Installing (syscall 0x08D9) a timer with
InternalTimerID == 0 tries to find a free user timer slot starting at timer 5!
The system timers 1..4 must be installed explicitly.

If one the timers is running, register A44D00D8 could be used a fine resolution timing device. It counts about 50000 times per second, t. i. 20ÁS per tick.

Hint! Timer handlers must not contain any direct display writing function! The fxCG-direct display functions are not reentrant. The user timer slots (5..10) are deinstalled, when switching from one application to another. A system timer handler must be positioned in an application-switch-secure area, f. i. some RAM. IL-memory would possibly be a good choice. Of course the binary loaded must be linked which appropriate relocation addresses.

(19.06.2011 08:50:36)