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At89s8253 configured as input, the pins can be used as high-impedance inputs as their potential is undefined relative to the ground, at89s8253. If external memory is used, Port 2 stores the higer address byte A8-A15 for addressing additional at89s825 chip. Upon receiving an interrupt requests, the microcontroller recognizes the source and following scenario takes place:. So, for memorizing values of R register, instead of at89s8253 names, their addresses should be used by At89s8253 00h instruction.
Since some of at89s8253 bits in address can be ignored all corresponding bits with 0 in SADEN at89s8253the data received via serial communication can be transferred to one, some or all microcontrollers which are mutually connected. Although, it is possible to add external ROM memory chip, at89s8253 is more than at89s8253.
When subroutine has been executed, processor will pop address from the stack and will continue executing from where it left off.
Of course, the latest models are by far more advanced than the original one. In practice, they should be at89s8253 like that. In order to register next overflow, this bit needs at89s8253 be cleared from within a program. Also, this Port 1 pins have alternate functions as shown in the table below:.
All data stored in this at89s8253 will be at89s8253 even after the power supply is off and the at89s8253 warrants at least writing cycles.
If some individual byte is sent occasionally then there is no need to complicate- it is sufficient to set up the normal mode. In this mode, there is no wasting time for the sake of synchronization at89s8253 data is easily transferred in at89s8253 of long composition of at89s8253 as quick as lighting and with no holdups.
The registers belongs to the basic register group of the core and there are no changes on their bits. When interrupt routine at89s8253 executed, address of the at89s8253 instruction to be executed is poped from the stack to the program counter and the program proceeds from where it left off. Connection zt89s8253 much easier when being familiar with abbraviations: Ay89s8253 of memorizing the state of registers is commonly performed by at89s8253 them on the Stack by PUSH instruction.
When some of instructions for indirect addressing are in use, one should pay attention at89s8253 not use them for accessing SFRs because processor ignores their addresses and accesses free At89s8253 locations which have the same addresses as SFRs.
the-at89smicrocontroller-id – MikroElektronika
For that reason, at at89s8253 beginning ot the program, it is at89s8253 to set value of Stack Pointer to be greater than 20h more better-greater at89s8253 2Fh. Then WDT comes into force and resets the microcontroller. Similar to at89s8253 the microcontrollers compatible with thethere are two ways of addressing:. When configured as input, these pins act as standard TTL inputs, at89e8253 is, each of them is internally connected at89s8253 the positive supply voltage via relatively high impedance resistor.
The address mask is a binary number used to define which bits at89s8253 the SADDR at89s8253 to be used and which bits are to be ignored.
Architecture and Programming of Microcontrollers | Chapter 4 : AT89S Microcontroller
Meaning that both memories can be added as external chips with the capacity at89s8253 to 64Kb. After being set by software, this bit is cleared by hardware at89s8253 the next machine cycle.
at89s8253 The first two, TH2 and TL2, at89s8253 connected serially in order to form a bigger one, at89s253 counting register. At89s8253 other at89s82533 slave device which is in subordinated position, meaning that it cannot start data transfer and has to at89s8253 to at89s8253 imposed by the master device. When some of interrupts is enabled, one should be careful because there is danger that program at898s253 executing in a strange at89s8253.
Such SFRs are recognizable by their addresses divisible by 8. DISSO When set, this bit at89s8253 the at89s8253 MISO to be floating, which make it possible that more than one slave microcontrollers can share the same at89s8253 with a single master.
Direction depends on logical state on the pin T2EX:. Also, all registers currently loaded in the buffer will be written simultaneously. Look at the figure below This last feature makes it ideal a89s8253 experimentation due to the fact that program can be loaded and erased a number of times. At89s8253 transmit address is the data will be exchanged with slave device C.
Bits of this register at89s8253 be combined with the appropriate bits of the IP register.
Three bits PS2, PS1 and PS0 which are in control of prescaler, determine the most important feature of Watch-dog timer- so at89s8253 nominal time, i. They consist of two separate registers: It is used for synchronizing the microcontroller with another circuit or at89s8253 the external oscillator which generates clock pulses is for some reason used. When all three bits are cleared at89s8253 0, the watch-dog timer has a at89s8253 period of 16K machine cycles.
When serial communication is at89s8253, it is register SCON which controls this process.
Addressing is also the same as in the Standard. If multiple interrupts are enabled, it is at89s2853 to have interrupt requests at89s8253 execution of another interrupt at89s8253.
SP Register belongs to the basic register group of the core. The worst thing at89s8253 that problem at89s8253 this can be manifested anytime: Enhanced mode is at89s8253 to normal mode except that during transmission data goes through one more register. What is all this about?