Z86L972 Datasheet, PDF (56/91 Pages) Zilog, Inc. – Low-Voltage Microcontrollers

Z86L972/Z86L973/Z86L974
Low-Voltage Microcontrollers
49
Table 13. SMR and Port Mode Registers (Group 0, Bank F, Registers 0–F)
Grp/Bnk Reg
(0Fh) rF
(0Fh) rE
(0Fh) rD
(0Fh) rC
(0Fh) rB
(0Fh) rA
(0Fh) r9
(0Fh) r8
(0Fh) r7
(0Fh) r6
(0Fh) r5
(0Fh) r4
(0Fh) r3
(0Fh) r2
(0Fh) r1
(0Fh) r0
Register Function
Reserved
Reserved
Reserved
Reserved
Stop Mode Recovery Register
Reserved
Reserved
Reserved
Reserved
Port 6 Mode
Port 5 Stop Mode Recovery
Port 5 Mode Register
Reserved
Port 4 Mode Register
Port 2 Stop Mode Recovery
Port Configuration Register
Identifier
SMR
P6M
P5SMR
P5M
P4M
P2SMR
P456CON
Register Error Conditions
Registers in the Z8 Standard Register File must be used correctly because certain
conditions produce inconsistent results and must be avoided.
• Registers F5h–F9h are write-only registers. If an attempt is made to read these
registers, FFh is returned. Reading any write-only register returns FFh.
• When the Register Pointer (register FDH) is read, the least significant four bits
(lower nibble) indicate the current Expanded Register File Bank. (For
example, 0000 indicates the Standard Register File, while 1010 indicates
Expanded Register File Bank A.)
• Writing to bits that are selected as timer outputs changes the I/O register but
has no effect on the pin signal.
• The Z8 instruction DJNZ uses any general-purpose working register as a
counter.
• Logical instructions such as OR and AND require that the current contents of
the operand be read. They do not function properly on write-only registers.
PS010504-1002
PRELIMINARY