Q & AVR MCU Series

or CALL instruction I did not do to jump to all the program memory
A program memory is organized into 4Kx16 the form of so only 4K program memory address space in the assembler, select “Options>> Wrap Relative Jumps” option when the program memory will allow you to skip the boundaries of example, if you from $ FFE to make a relative jump $ 00A program counter will be increased by 12 and the border hidden program memory can only be used this feature of the MCU 8K 4K 16K microcontroller do not hide the border of SCM to use JUMP and CALL instructions.
Q: When I use the UART when the timer / counter can be used to generate any baud rate is?
A does not have a dedicated timer is used to generate the UART baud rate of all the timer / counter can be used for general purposes only
Q: How can AT90S1200 from the outside will wake up from Power-down mode?
A wake-up from Power-down mode AT90S1200 you must enable the external interrupt INT0 interrupt and is low in power-down mode when you go to sleep if the INT0 pin low when the hold time is greater than the internal RC oscillator 16384 AT90S1200 wake cycle will be the internal RC oscillator is used to delay the start until the MCU XTAL oscillator is stable reference AT90S1200 Data Book RC oscillator frequency is affected by the VCC voltage
Q: When I use the SBI and CBI instructions to set or clear the I / O port when a signal bit the same port will affect the other bits?
A microcontroller is not like most of the AVR microcontroller that allows you to safely operate 100% of I / O port signal level This also applies to the operation of the port in doubt refer to each I / O port of the three addresses
Q: Why does every I / O port has three addresses?
A. To enable you to create a 100% secure system to support real time AVR – modify – write I / O port if you want to read I / O pins of the physical-level read PIN when you want to change the output register when the read lock PORT to ensure correct data storage is written back to the port to ensure that all output has always been this way can give you the desired results without relying on the physical level pin this feature to save you for a copy of the safety system port the data into your memory of all this work when you use a lot of commands using SBI and CBI instructions to set / clear I / O port when the signal bit address must always use PORT
Q: Why is SBI and CBI instructions only on the $ 00 – $ 1F of the I / O registers to operate?
All AVR instructions A few exceptions are two-byte length which means that only 65,536 (64K) possible combinations to arrange the AVR instruction set, instruction set, when we take the specified number of compromises to the fullest possible Unlike the use of these combinations 64K CISC instruction can be a microcontroller, two, three or more bytes of the structure of the AVR instructions we can not achieve all of examples like this as an immediate address register and contains all 32 address 8-bit instructions and registers a constant need to address the need for other five all this instruction will occupy space in the 8K instruction mix in other words we can only be eight such instructions are no more instructions can be achieved if be a length of 17 instructions is not economical and convenient scheme will not be considered in the design process AVR instruction set to set up our righteousness we have heard a lot of construction of the C compiler expert advice on how to adjust their instruction set to accommodate the C compiler, a number of suggestions put forward as an example the compiler experts suggest that we brought into place for the immediate SBCI sacrifice ADDI instruction subtraction
Operating instructions for those missing the AVR is easy to prove that the code efficiency should be the realization that we have to find a command instructions and omitted a good way to compromise between
Q: Why now addressing instruction register R0-R15 can not work?
All AVR instructions A few exceptions are two-byte length which means that only 65,536 (64K) possible combinations to arrange the AVR instruction set, instruction set, when we take the specified number of compromises to the fullest possible Unlike the use of these combinations 64K CISC instruction can be a microcontroller, two, three or more bytes of the structure of the AVR instructions we can not achieve all of examples like this as an immediate address register and contains all 32 address 8-bit instructions and registers a constant need to address the need for other five all this instruction will occupy space in the 8K instruction mix in other words we can only be eight such instructions are no more instructions can be achieved while be a length of 17 instructions is not economical and convenient scheme will not be considered in the design process AVR instruction set we listened to a lot of set building meaning we turned to experts in