UPD17231 datasheet(29/94 Pages) RENESAS

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Data Sheet U14360EJ1V0DS00

µPD17230, 17231, 17232, 17233, 17234, 17235, 17236

2.5.2

Control registers

The control registers consists of a total of 64 nibbles (64 x 4 bits) of the addresses 00H-3FH of the register file.

Of these, however, only 16 nibbles are actually used. The remaining 48 nibbles are unused registers that are

inhibited from being read or written.

When the “PEEK WR, rf” instruction is executed, the contents of the register file addressed by “rf” are read to the

window register.

When the “POKE rf, WR” instruction is executed, the contents of the window register are written to the register

file addressed by “rf”.

When using the assembler (RA17K), the macro instructions listed below, which are embedded as flag type symbol

manipulation instructions, can be used. The macro instructions allow the contents of the register file to be manipulated

in bit units.

For the configuration of the control register, refer to Figure 11-1 Register File List.

SETn

: Sets flag to “1”

CLRn

: Sets flag to “0”

SKTn

: Skips if all flags are “1”

SKFn

: Skips if all flags are “0”

NOTn

: Complements flag

INITFLG

: Initializes flag

INITFLGX : Initalizes flag

2.5.3

Notes on using register files

When using the register files, bear in mind the points described below. For details, refer to

µPD172xx subseries

User’s Manual (U12795E).

(1) When manipulating control registers (read-only and unused registers)

When manipulating the write-only (W), the read-only (R) and unused control registers by using the assembler

or in-circuit emulator, keep in mind the following points:

•

When device operates

Nothing changes even if data is written to the read-only register.

If the unused register is read, an undefined value is read; nothing is changed even if data is written to this

•

Using assembler

An error occurs if instruction is excecuted to read data to the write-only register.

An error occurs if an instruction is executed to write data to the read-only register.

An error also occurs if an instruction is executed to read or write the unused address.

•

When an in-circuit emulator (IE-17K or IE-17K-ET) is used (when instruction is executed for patch

processing)

An undefined value is read if the write-only register is read, and an error does not occur.

Nothing changes even if data is written to the read-only register, and an error does not occur.

An undefined value is read if the unused address is read; nothing changes even if data is written to this

address. An error does not occur.

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