Notes When Writing Data In A Register Having The Status Flag - Cypress CY91590 Series Hardware Manual

Handling the Device

2.3.3 Notes When Writing Data in a Register Having the Status Flag

This section explains notes when writing data in a register having the status flag.
When writing data in the register that has a status flag (especially, an interrupt request flag) to control function, taking care
not to clear its status flag erroneously must be followed.
The program must be written not to clear the flag to the status bit, and then to set the control bits to have the desired value.
Especially, if multiple control bits are used, the bit instruction cannot be used. (The bit instruction can access to a single bit
only.) By the Byte, Half-word, or Word access, data is written to the control bits and status flag simultaneously. During this
time, take care not to clear other bits (in this case, the bits of status flag) erroneously.
Note:
It is not necessary to note that the bit instruction considers this respect compared with the register to which read-modify-
write (RMW) is supported. When the bit instruction is used for the register to which read-modify-write (RMW) is not
supported, it is necessary to note it.
CY91590 Series FR81S Hardware Manual, Document Number: 002-05526 Rev. *B 152