Three-level Program Memory Lock. Low-power Idle and Power-down Modes. Interrupt Recovery From Power-down. The device is manufactured using Atmel ‘s high-density nonvol. The on-chip downloadable Flash allows the program mem.
By combining a versatile 8-bit CPU. The AT89S provides the following standard features: The Power-down mode saves the RAM contents but. The downloadable Flash can be changed a single byte at a at898s252 and is accessible.
In this mode, P0 has internal.
Port 0 also receives the code bytes during Flash program. External pullups are required during program. When 1s are written to Port 1 pins, they are ah89s8252 high by. Port 1 pins that are externally being pulled low will source. Port 0 can also be configured to be the multiplexed low. Some Port 1 pins provide additional functions. Port 3 pins that are externally being pulled low will source. Port 3 also serves the functions of various special features.
Port 3 also receives some control signals for Flash pro. RXD serial input port. Eatasheet serial output port. INT0 external interrupt 0. INT1 external interrupt 1. T0 timer 0 external input.
T1 timer 1 external input. SS Slave port select input. WR external data memory write strobe. MOSI Master data output, slave data input pin. RD external data memory read strobe. MISO Master data input, slave data output pin. A high on this pin for two machine cycles while.
SCK Master clock output, slave clock input pin. Port 1 also receives the low-order address bytes during. Address Latch Enable is an output pulse for latching the. Flash programming and verification. This pin is also the program pulse input PROG during. When 1s are written to At89s8522 2 pins, they are pulled high by.
Note, however, that one ALE. Port 2 st89s8252 that are externally being pulled low will source. If desired, ALE operation can be disabled by setting bit 0 of. Port 2 emits the high-order address byte during fetches. With the bit set, ALE is active only dur. Otherwise, the pin is. Setting the ALE-disable bit has no. Datasheeg this application, Port 2 uses strong internal pul. During accesses to external data. Program Store Enable is the read strobe to external pro. Port 2 also receives the high-order address bits and some.
When the AT89S is executing code from external pro. When 1s are written to Port 3 pins, they are pulled high by. EA must be strapped to GND in. Note, however, at89s82522 if lock bit 1 is programmed, EA will be.
Input to the inverting oscillator amplifier and input to the. EA should be strapped to V CC for internal program execu. This pin also receives the volt programming. Output from the inverting oscillator amplifier. A map of the on-chip memory area called the Special Func. In that case, the reset or inactive values.
AT89S Datasheet(PDF) – ATMEL Corporation
Note that not all of the addresses are occupied, and unoc. Timer 2 Registers Control and status bits are contained in. Read accesses to these addresses will in general return. Table 9 for Timer 2. User software should not write 1s to these unlisted. Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set when either. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock in serial port. Modes 1 and 3. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock in serial port.
Timer 2 external enable. When set, allows a capture or reload to occur as a result of a negative transition on T2EX if. Timer 2 is not being used to clock the serial port. Timer or counter select for Timer 2. Prescaler Bits for the Watchdog Timer. When all three bits are set to “0”, the watchdog timer has a nominal period of. When all three bits are set to “1”, the nominal period is ms.
Data Pointer Register Select. Each time this bit is set to “1” by user software, a pulse is. While programming operations are being executed. Watchdog Timer Enable Bit. Dual Data Pointer Registers To facilitate accessing both. The SPI data bits.
Writing the SPI data. The SPDR is double buff. The user should always initialize the DPS bit to the. Interrupt Registers The global interrupt enable bit and the. POF is set to “1” during. It can be set and reset under software control.
Two priorities can be set for each of the. These two bits control the SCK rate of the device configured as master. The WDT is reset datashset setting the. That means the upper bytes have the.
When the Datasyeet times out without. When an instruction accesses an internal location above.
AT89S8252 Datasheet PDF
Watchdog Timer Period Selection. Instructions that use direct. For example, the following direct addressing instruction. Instructions that use indirect addressing access the upper. For example, the following indirect. Note that s tack operations are examples of indirec t.
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