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MESC TOOL NEWS:
MESCT-MR308-991001D
MR308 V.1.00 Release 1
Precaution
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Please take note of the following problems in using real-time OS MR308 for the M16C/80 series of microcomputers.
- Problems
When INT instructions are used to issue system calls in MR308, the two problems described bellow may occur at processing specific system calls. They are related to the symptom described in MESC Technical News No.M16C-37-9910 "Note on Using INT Instruction in M16C/80 Group MCUs" issued on October 1, 1999.
However, all the functions of MR308 except these problems, for instance, OS functions and applications before and after processing specific system calls, are not affected.
- (1)An interrupt disable period during processing a system call may become longer.
- An OS-dependent interrupt handler may not be invoked during processing a system call. This is due to the fact that an interrupt disable period is extended to the time period required to process the system call.
- (2)When the processor interrupt priority level (IPL) is set to any value except 0 at processing a task, an interrupt handler with a priority lower than or equal to the IPL value may be invoked during processing a system call that has been issued by the task.
- (Since IPL is usually not set at processing a task, IPL goes to 0 during execution of the task. Therefore, this is not the case mentioned above.)
- Conditions
- 2.1 The problem described in 1-(1) above may occur when the following system calls are issued:
- sta_tsk, ext_tsk, ter_tsk, ena_dsp, chg_pri, rot_rdq, rel_wai,
- sus_tsk, rsm_tsk, slp_tsk, tslp_tsk, wup_tsk, set_flg, clr_flg,
- wai_flg, twai_flg, sig_sem, wai_sem, twai_sem, snd_msg, rcv_msg,
- trcv_msg, unl_cpu, dly_tsk, pget_blk, rel_blk, loc_cpu
- 2.2 In addition to the above condition, when IPL is set to any value except 0 at processing a task, and interrupt handlers with a priority lower than or equal to the IPL value exist, the problem described in 1-(2) above may occur.
- Schedule of Fixing Problems
We plan to fix these problems in our next release.
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