upd17240 Renesas Electronics Corporation., upd17240 Datasheet - Page 30

• Manufacturer Part Number: upd17240
• Description: 4-bit Single-chip Microcontrollers For Small General-purpose Infrared Remote Control Transmitters
• Manufacturer: Renesas Electronics Corporation.

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(3) Notes on using data buffer
When transferring data to/from the peripheral hardware via the data buffer, the unused peripheral addresses,
write-only peripheral registers (only when executing PUT), and read-only peripheral registers (only when
executing GET) must be handled as follows.
• When device operates
• Using assembler
• If an in-circuit emulator (IE-17K or IE-17K-ET) is used (when an instruction is executed for patch
Nothing changes even if data is written to a read-only register.
If an unused address is read, an undefined value is read. Nothing changes even if data is written to that
address.
An error occurs if an instruction is executed to read a write-only register.
Again, an error occurs if an instruction is executed to write data to a read-only register.
An error also occurs if an instruction is executed to read or write an unused address.
processing)
An undefined value is read if an attempt is made to read the data of a write-only register, but an error does
not occur.
Nothing changes even if data is written to a read-only register, and an error does not occur.
An undefined value is read if an unused address is read; nothing changes even if data is written to this
address. An error does not occur.
µ PD17240, 17241, 17242, 17243, 17244, 17245, 17246
Data Sheet U15002EJ1V1DS