ZLF645S0P2832G Zilog, ZLF645S0P2832G Datasheet - Page 50

• Manufacturer Part Number: ZLF645S0P2832G
• Description: Microcontrollers (MCU) 32K Flash 512B RAM 28 pin
• Manufacturer: Zilog

Specifications of ZLF645S0P2832G

• Data Bus Width: 8 bit
• Program Memory Type: Flash
• Program Memory Size: 32 KB
• Data Ram Size: 512 KB
• Interface Type: ICP, UART
• Maximum Clock Frequency: 8 MHz
• Number Of Programmable I/os: 24
• Number Of Timers: 3
• Maximum Operating Temperature: + 70 C
• Mounting Style: Through Hole
• Package / Case: PDIP-28
• Minimum Operating Temperature: 0 C
• Lead Free Status / Rohs Status: Details

PS026407-0408
Register File
Stack
The ZLF645 Series of Flash MCUs features up to 1024 bytes of register file space,
organized in 256-byte banks. Bank 0 contains 235 or 237 bytes of RAM addressed as
general purpose registers, 5 or 3 port addresses, and 16 control register addresses. For
20- or 28-pin packages, Port 1 and Port 4 registers of Bank 0 are not implemented and
there locations are available as general-purpose registers. Bank 1, Bank 2, and Bank 3;
each contain 256 general-purpose register bytes. Bank D and Bank F; each contain 16
addresses for control registers. All other banks are reserved and must not be selected.
The current bank is selected for 8-bit direct or indirect addressing by writing Register
Pointer bits RP[3:0]. In the current bank, a 16-byte working register group (addressed as
R0–R15) is selected by writing RP[7:4]. A working register operand requires only 4 bits
of Program Memory. There are 16 working register groups per bank (see
Figure
The 8-bit addresses in the range
bank-independent, meaning they always access the control registers in Bank 0, regardless
of the RP[3:0] value. Addresses in the range
registers unless Bank D or Bank F is selected (Port 01h is not implemented in this device).
When Bank D or Bank F is selected, addresses 10h–EFh access the Bank 0 general-
purpose registers.
The LDX and LDXI instructions or indirect addressing is used to access the Bank 1–3
registers not accessible by 8-bit or working register addresses (12-bit addresses—100h–
103h, 1F0h–1FFh, 200h–203h, 2F0h–2FFh, 300h–303h, and 3F0h–3FFh). See
Memory Addressing
The Stack Pointer register provides either 16-bit or 8-bit of stack pointer addressability
depending upon the programming of bit 3 of User Option Byte 1 (for more details, see
Flash Option Bits
16-bit Stack Addressability
When programmed for 16-bit stack addressability, the stack address is formed as a
combination of the SPL and SPH registers located at addresses FFh and FEh. For 1K and
512 B RAM products, the most significant 6 or 5 bits, respectively of the SPH register are
ignored. The stack address is mapped to a particular RAM memory location by the
following formula:
Bank = {2'b0, SPH[1:0]}
Group = SPL[7:4]
Register number = SPL[3:0]
With the ZLF645 MCU configured for 16-bit stack addressability, stack reads or writes to
Bank 3, 2, 1, or 0 Group F Registers or to any of the Port registers actually accesses
14).
on page 166).
on page 45.
F0h
–
FFh
(and the equivalent 4-bit addresses) are
00h
–
03h
ZLF645 Series Flash MCUs
always access the Bank 0 Port
Product Specification
Figure 13
Register File
Linear
and
42