DR805x Instructions set details
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1. OVERVIEW
1.1. DOCUMENT STRUCTURE.
Document contains brief description of DR805X instructions. This manual is intended
for design engineers who are planning to use the DR805X HDL core in conjunction with
software assembler, compiler and debugger tools.
2. INSTRUCTIONS SET BRIEF
2.1. INSTRUCTION SET NOTES
The DR805X has five different addressing modes: immediate, direct, register, indirect
and relative. In the immediate addressing mode the data is contained in the opcode. By
direct addressing an eight bit address is a part of the opcode, by register addressing, a
register is selected in the opcode for the operation. In the indirect addressing mode, a
register is selected in the opcode to point to the address used by the operation. The
relative addressing mode is used for jump instructions.
The following tables give a survey about the instruction set cycles of the DR805X
microcontroller core. One cycle is equal to one clock period.
Table 1 and Table 2 contain notes for mnemonics used in Instruction set tables. Tables 3 -
7 show instruction hexadecimal codes, number of bytes and machine cycles that each
instruction takes to execute.
Rn
Working register R0-R7
direct
@Ri
#data
#data 16
bit
128 internal RAM locations, any Special Function Registers
Indirect internal or external RAM location addressed by register R0 or R1
8-bit constant included in instruction
16-bit constant included as bytes 2 and 3 of instruction
256 software flags, any bit-addressable l/O pin, control or status bit
Accumulator
A
B
B working register
C
Carry flag
Table 1. Notes on data addressing modes
addr16
addr11
rel
Destination address for LCALL and LJMP may be anywhere within the 64-Kbyte of
program memory address space.
Destination address for ACALL and AJMP will be within the same 2-Kbyte page of
program memory as the first byte of the following instruction.
SJMP and all conditional jumps include an 8-bit offset byte. Range is +127/-128
bytes relative to the first byte of the following instruction
Table 2. Notes on program addressing modes
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