48
CY8C28xxx PSoC Programmable System-on-Chip TRM, Document No. 001-52594 Rev. *G
CPU Core (M8C)
2.7
Register Definitions
The following register is associated with the CPU Core (M8C). The register description has an associated register table show-
ing the bit structure. The bits that are grayed out in the table are reserved bits and are not detailed in the register description
that follows. Reserved bits should always be written with a value of ‘0’.
2.7.1
CPU_F Register
The M8C Flag Register (CPU_F) provides read access to
the M8C flags.
Bits 7 and 6: PgMode[1:0].
PgMode determines how the
CUR_PP, STK_PP, and IDX_PP registers are used in form-
ing effective RAM addresses for Direct Address mode and
Indexed Address mode operands. PgMode also determines
whether the stack page is determined by the STK_PP or
IDX_PP register.
Bit 4: XIO.
The I/O Bank Select bit, also known as the reg-
ister bank select bit, is used to select the register bank that
is active for a register read or write. This bit allows the PSoC
device to have 512 8-bit registers and therefore, can be
thought of as the ninth address bit for registers. The address
space accessed when the XIO bit is set to ‘0’ is called the
, while the address space accessed when the
XIO bit is set to ‘1’ is called the
.
Bit 2: Carry.
The Carry flag bit is set or cleared in response
to the result of several instructions. It can also be manipu-
lated by the flag-logic opcodes (for example, OR F, 4). See
the
PSoC Designer Assembly Guide User Manual
for more
details.
Bit 1: Zero.
The Zero flag bit is set or cleared in response
to the result of several instructions. It can also be manipu-
lated by the flag-logic opcodes (for example, OR F, 2). See
the
PSoC Designer Assembly Guide User Manual
for more
details.
Bit 0: GIE.
The state of the Global Interrupt Enable bit
determines whether interrupts (by way of the interrupt
request (IRQ)) will be recognized by the M8C. This bit is set
or cleared by the user, using the flag-logic instructions (for
example, OR F, 1). GIE is also cleared automatically when
an interrupt is processed, after the flag byte has been stored
on the stack, preventing nested interrupts. If desired, the bit
can be set in an
interrupt service routine (ISR)
.
For GIE = 1, the M8C samples the IRQ input for each
instruction. For GIE = 0, the M8C ignores the IRQ.
For additional information, refer to the
.
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Access
x,F7h
PgMode[1:0]
XIO
Carry
Zero
GIE
RL : 02h
LEGEND
L
The AND F, expr; OR F, expr; and XOR F, expr flag instructions can be used to modify this register.
x
An “x” before the comma in the address field indicates that this register can be read or written to no matter what bank is used.
Summary of Contents for CY8C28 series
Page 65: ...64 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G RAM Paging ...
Page 125: ...124 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Page 311: ...310 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G IDAC_CR0 1 FDh ...
Page 317: ...316 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Page 393: ...392 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Page 477: ...476 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Digital Clocks ...
Page 561: ...560 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...