Datasheet HT68F2420 (Holtek) - 52

HT68F2420 HT68F2420 High Precision HIRC Flash MCU High Precision HIRC Flash MCU Instruction Set Introduction
Central to the successful operation of any microcontroller is its instruction set, which is a set of program instruction codes that directs the microcontroller to perform certain operations. In the case of Holtek microcontroller, a comprehensive and flexible set of over 60 instructions is provided to enable programmers to implement their application with the minimum of programming overheads. For easier understanding of the various instruction codes, they have been subdivided into several functional groupings.
Instruction Timing
Most instructions are implemented within one instruction cycle. The exceptions to this are branch, call, or table read instructions where two instruction cycles are required. One instruction cycle is equal to 4 system clock cycles, therefore in the case of an 8MHz system oscillator, most instructions would be implemented within 0.5μs and branch or call instructions would be implemented within 1μs. Although instructions which require one more cycle to implement are generally limited to the JMP, CALL, RET, RETI and table read instructions, it is important to realize that any other instructions which involve manipulation of the Program Counter Low register or PCL will also take one more cycle to implement. As instructions which change the contents of the PCL will imply a direct jump to that new address, one more cycle will be required. Examples of such instructions would be "CLR PCL" or "MOV PCL, A". For the case of skip instructions, it must be noted that if the result of the comparison involves a skip operation then this will also take one more cycle, if no skip is involved then only one cycle is required.
Moving and Transferring Data
The transfer of data within the microcontroller program is one of the most frequently used operations. Making use of three kinds of MOV instructions, data can be transferred from registers to the Accumulator and vice-versa as well as being able to move specific immediate data directly into the Accumulator. One of the most important data transfer applications is to receive data from the input ports and transfer data to the output ports.
Arithmetic Operations
The ability to perform certain arithmetic operations and data manipulation is a necessary feature of most microcontroller applications. Within the Holtek microcontroller instruction set are a range of add and subtract instruction mnemonics to enable the necessary arithmetic to be carried out. Care must be taken to ensure correct handling of carry and borrow data when results exceed 255 for addition and less than 0 for subtraction. The increment and decrement instructions INC, INCA, DEC and DECA provide a simple means of increasing or decreasing by a value of one of the values in the destination specified. Rev. 1.00 52 October 08, 2020 Rev. 1.00 53 October 08, 2020 Document Outline Features CPU Features Peripheral Features General Description Block Diagram Pin Assignment Pin Description Absolute Maximum Ratings D.C. Characteristics Operating Voltage Characteristics Operating Current Characteristics Standby Current Characteristics A.C. Characteristics Internal Oscillator Characteristics System Start Up Time Characteristics Input/Output Characteristics REM/REMDRV Pin Characteristics LVR Electrical Characteristics Power on Reset Characteristics System Architecture Clocking and Pipelining Program Counter Stack Arithmetic and Logic Unit – ALU Flash Program Memory Structure Special Vectors Look-up Table Table Program Example In Circuit Programming – ICP On-Chip Debug Support – OCDS Data Memory Structure General Purpose Data Memory Special Purpose Data Memory Special Function Register Description Indirect Addressing Registers – IAR0 Memory Pointers – MP0 Accumulator – ACC Program Counter Low Register – PCL Look-up Table Registers – TBLP, TBLH Status Register – STATUS Oscillators Oscillator Overview System Clock Configurations Internal RC Oscillator – HIRC Internal 32kHz Oscillator – LIRC Operating Modes and System Clocks System Clocks System Operation Modes Control Register Operating Mode Switching Standby Current Considerations Wake-up Watchdog Timer Watchdog Timer Clock Source Watchdog Timer Control Register Watchdog Timer Operation Reset and Initialisation Reset Functions Reset Initial Conditions Input/Output Ports Pull-high Resistors I/O Pin Wake-up I/O Port Control Registers I/O Pin Structures Programming Considerations 9-bit Timer with Carrier Output Timer and Carrier Output Conctrol Register Timer Operation Carrier Output Carrier Output Pins Interrupts Interrupt Register Interrupt Operation Time Base Interrupt Interrupt Wake-up Function Programming Considerations Application Circuits Instruction Set Introduction Instruction Timing Moving and Transferring Data Arithmetic Operations Logical and Rotate Operation Branches and Control Transfer Bit Operations Table Read Operations Other Operations Instruction Set Summary Table Conventions Instruction Definition Package Information 8-pin SOP (150mil) Outline Dimensions 16-pin NSOP (150mil) Outline Dimensions 20-pin NSOP (150mil) Outline Dimensions 20-pin SSOP (150mil) Outline Dimensions