Z86L972 Datasheet, PDF (16/91 Pages) Zilog, Inc. – Low-Voltage Microcontrollers

Z86L972/Z86L973/Z86L974
Low-Voltage Microcontrollers
9
capabilities of the Z8 CPU. No special I/O instructions are necessary because the
I/O is mapped into the register file.
CPU Control Registers
The standard Z8 control registers govern the operation of the CPU. Any instruc-
tion which references the register file can access these control registers. The fol-
lowing are available control registers:
• Register Pointer (RP)
• Stack Pointer (SP)
• Program Control Flags (FLAGS)
• Interrupt Control (IPR, IMR, and IRQ)
• Stop Mode Recovery (SMR, P2SMR, and P5SMR)
• Low-Battery Detect (LB) Flag
The Z8 uses a 16-bit Program Counter (PC) to determine the sequence of current
program instructions. The PC is not an addressable register.
Peripheral registers are used to transfer data, configure the operating mode, and
control the operation of the on-chip peripherals. Any instruction that references
the register file can access the peripheral registers. The following are peripheral
control registers:
• T1 Timer/Counter (TMR, T1, and PRE1)
• T8 Timer/Counter (CTR0, HI8, LO8, TC8H, and TC8L)
• T16 Timer/Counter (CTR2, HI16, LO16, TC16H, and TC16L)
• T8/T16 Control Registers (CTR1 and CTR3)
In addition, the four port registers are considered to be peripheral registers. The
following are port control registers:
• Port Configuration Registers (P456CON and P3M)
• Port 2 Control and Mode Registers (P2 and P2M)
• Port 4 Control and Mode Registers (P4 and P4M)
• Port 5 Control and Mode Registers (P5 and P5M)
• Port 6 Control and Mode Registers (P6 and P6M)
The functions and applications of the control and peripheral registers are
explained in “Control and Status Registers” on page 47.
PS010504-1002
PRELIMINARY