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Questions and Answers
The 'COM Rd' instruction inverts the contents of Rd and places the result back into the Rd ______
register
The AVR flag register to indicate arithmetic conditions is called ______ register
status
The bits C, Z, N, V, S, and H are called conditional ______
flags
The carry flag 'C' is set whenever there is a carry out from the D7 ______
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If the result is zero, Z = ______
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EEPROM in AVR chips does not lose its data when power is off, whereas _________ does
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EEPROM is used for storing data that should rarely be changed and should not be lost when the power is off; whereas _________ is used for storing data and parameters that are changed frequently
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The GPRS, SFRs, and internal data _________ are made of SRAM
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In AVR datasheets, EEPROM refers to the EEPROM’s size, and _________ is the internal SRAM size
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LDS Instruction (LoaD direct from data Space) tells the CPU to load one byte from an address in the data memory to the GPR; the location in the data memory can be in any part of the _________
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STS Instruction (STore direct to data Space) tells the CPU to store the contents of the GPR to an address location in the data memory space; the location can be in any part of the _________ space
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The negative flag reflects the result of an ______ operation
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If the D7 bit of the result is zero, then N = 0 and the result is ______
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The Overflow flag is set whenever the result of a signed number operation is too large, causing the high-order bit to overflow into the ______ bit
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The carry flag is used to detect errors in unsigned arithmetic operations while the overflow flag is used to detect errors in signed ______ operations
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The Half carry flag is set if there is a carry from D3 to D4 during an ADD or SUB operation; otherwise, it is ______
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The AVR microcontroller has only one data type (8-bit) and the size of each register is also 8 bits. It is the job of the programmer to break down data larger that 8 bits to be processed by the ______
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Assembler directives give directions to the ______
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The .EQU (equate) directive is used to define a constant ______
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The .ORG (origin) directive is used to indicate the beginning of the ______
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Assembly languages provided mnemonics for the machine code instructions, plus other features that made programming faster and less prone to ______
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The 'asm' source file containing the program is fed to the AVR ______
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The 'hex' file is burned into the AVR’s program ______
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The 'eep' file is burned into the AVR’s ______
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The 'obj' file is used as an input to a ______ or an emulator
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Assemblers assume that the 'lst' file is not wanted unless you indicate that you want to ______ it
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The address bus is ______ bits wide.
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In the AVR architecture, the program ROM space uses the ______ endian method.
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The AVR microcontrollers use ______ architecture to increase processing power.
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RISC architecture aims to simplify by reducing the number of ______.
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The big cost of implementing a large number of instructions led to the idea of reducing the number of ______.
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The AVR microcontrollers employ three methods to increase processing power: increasing clock frequency, using Harvard Architecture, and adopting ______ architecture.
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Study Notes
AVR Microcontroller Instructions and Registers
- The 'COM Rd' instruction inverts the contents of register Rd and stores the result back in Rd.
- The flag register that indicates arithmetic conditions in AVR is known as the status register.
- Conditional flags in the AVR system include C (Carry), Z (Zero), N (Negative), V (Overflow), S (Sign), and H (Half-carry).
Flags and Data Storage
- Carry flag 'C' is activated when there is a carry-out from the highest bit (D7).
- If a computation results in zero, the Zero flag (Z) is set to true.
- EEPROM retains data even when power is turned off, while SRAM loses its data during power loss.
- EEPROM is designated for infrequent changes and essential data retention, whereas SRAM is utilized for frequently changing data and parameters.
Memory Structure
- Components like GPRS, SFRs, and internal data are constructed using SRAM.
- In AVR specifications, EEPROM size references non-volatile memory size, while SRAM size refers to volatile memory capacity.
- The LDS instruction loads a single byte from data memory into the general-purpose register (GPR), allowing access to any part of the memory.
- The STS instruction stores the content of a GPR into a specified address within the data memory space.
Operations and Flags
- The negative flag correlates with results from arithmetic operations.
- If the D7 bit is zero, it indicates that the negative flag (N) is clear and the result is non-negative.
- The Overflow flag is activated when a signed operation's result exceeds the allowable range, causing a bit overflow.
- The carry flag detects errors in unsigned arithmetic, while the overflow flag identifies errors in signed operations.
- The Half carry flag becomes set if there’s a carry from D3 to D4 in ADD or SUB operations; otherwise, it remains clear.
Programming and Directives
- The AVR microcontroller processes only 8-bit data types, requiring programmers to manage larger data by breaking it down.
- Assembler directives guide the assembler in processing instructions.
- The .EQU directive defines constant values, while the .ORG directive marks the start of a program in memory.
File Types in AVR Programming
- The 'asm' source file contains the program code for the AVR.
- The 'hex' file is programmed into the AVR's flash memory, while the 'eep' file is for EEPROM programming.
- The 'obj' file is used as input for a linker or emulator.
- Assemblers do not automatically generate the 'lst' file unless requested.
Architecture and Efficiency
- The address bus in AVR systems is typically 16 bits wide.
- The AVR architecture employs the little-endian method for program ROM space.
- It utilizes Harvard architecture to separate instruction and data memory, enhancing processing power.
- RISC (Reduced Instruction Set Computing) architecture reduces instruction complexity by minimizing the number of instructions.
- It aims to avoid the performance cost associated with a large instruction set by streamlining the instruction execution process.
- AVR’s processing power is amplified through higher clock frequencies, utilization of Harvard architecture, and RISC principles.
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Description
Test your knowledge on the differences between EEPROM and SRAM in AVR chips. Learn about the purposes of EEPROM and SRAM, as well as their functions in storing data. Explore the distinctions between EEPROM's ability to retain data when power is off and SRAM's frequent data changes.
