HD6432670 Hitachi, HD6432670 Datasheet - Page 101

• Manufacturer Part Number: HD6432670
• Description: (HD64F267x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

2.9
2.9.1
The BSET, BCLR, BNOT, BST, and BIST instructions are used to read data in byte-wise, operate
the data in bit-wise, and write the result of the bit-wise operation in bit-wise again. Therefore,
special care is necessary to use these instructions for the registers and the ports that include write-
only bit.
The BCLR instruction can be used to clear the flags in the internal I/O registers to 0. In this time,
if it is obvious that the flag has been set to 1 in the interrupt handler, there is no need to read the
flag beforehand.
Notes: 1. From any state except hardware standby mode, a transition to the reset state occurs whenever
2. In every state, when the STBY pin becomes low, the hardware standby mode is entered.
3. For details, refer to section 22, Power-Down Modes.
A transition can also be made to the reset state when the watchdog timer overflows.
Usage Note
Usage Notes on Bit-wise Operation Instructions
Bus-released state
handling state
Reset state
Exception
Reset state
*1
= High
Figure 2.13 State Transitions
External interrupt request
Program execution state
End of bus request
Bus request
= Low
= High,
Rev. 2.0, 04/02, page 55 of 906
Hardware standby
Software standby
Power down state
Sleep mode
mode
mode
*2
*3
goes low.