Datenblatt-Suchmaschine für elektronische Bauteile |
|
8XC51R Datenblatt(PDF) 6 Page - Intel Corporation |
|
8XC51R Datenblatt(HTML) 6 Page - Intel Corporation |
6 / 20 page 8XC51RARBRC Table 2 Status of the External Pins during Idle and Power Down Mode Program ALE PSEN PORT0 PORT1 PORT2 PORT3 Memory Idle Internal 1 1 Data Data Data Data Idle External 1 1 Float Data Address Data Power Down Internal 0 0 Data Data Data Data Power Down External 0 0 Float Data Data Data Mode will be exited if the chip is reset or if an en- abled interrupt occurs POWER DOWN MODE To save even more power a Power Down mode can be invoked by software In this mode the oscillator is stopped and the instruction that invoked Power Down is the last instruction executed The on-chip RAM and Special Function Registers retain their val- ues until the Power Down mode is terminated On the 8XC51RX either a hardware reset or an ex- ternal interrupt can cause an exit from Power Down Reset redefines all the SFRs but does not change the on-chip RAM An external interrupt allows both the SFRs and on-chip RAM to retain their values To properly terminate Power Down the reset or ex- ternal interrupt should not be executed before VCC is restored to its normal operating level and must be held active long enough for the oscillator to restart and stabilize (normally less than 10 ms) With an external interrupt INT0 and INT1 must be enabled and configured as level-sensitive Holding the pin low restarts the oscillator but bringing the pin back high completes the exit Once the interrupt is serviced the next instruction to be executed after RETI will be the one following the instruction that put the device into Power Down DEDICATED HARDWARE WATCHDOG TIMER (One-Time Enabled with Reset-Out) The 8XC51RX contains a dedicated WatchDog Tim- er (WDT) to allow recovery from software or hard- ware upset WDT is disabled upon power-up To en- able the WDT user must write 1EH and E1H in se- quence to WDTRST Special Function Register Once the WDT is enabled the 14-bit counter will increment every machine cycle While the oscillator is running the WDT will be incrementing and cannot be disabled The counter is reset by writing 1EH and E1H in sequence to the WDTRST If the counter is not reset before it reaches 3FFFH (16383D) the chip will be forced into reset sequence and the WDT will be disabled as upon power-up During this reset the chip will drive an output Reset-High pulse for the duration of 96 x TOSC at the RST pin The duration of the Reset-High pulse works out to 600 ms 16 MHz While in the Idle mode the WDT continues to count If the user does not wish to exit the Idle mode with a reset then the processor must periodically ‘‘woken up’’ to service the WDT In Power Down mode the WDT stops counting and holds its current value DESIGN CONSIDERATION The window on the D87C51RX must be covered by an opaque label Otherwise the DC and AC characteristics may not be met and the device may be functionally impaired When the idle mode is terminated by a hardware reset the device normally resumes program exe- cution from where it left off up to two machine cycles before the internal reset algorithm takes control On-chip hardware inhibits access to inter- nal RAM in this event but access to the port pins is not inhibited To eliminate the possibility of an unexpected write when Idle is terminated by re- set the instruction following the one that invokes Idle should not be one that writes to a port pin or to external memory NOTE For more detailed information on the reduced power modes refer to current Embedded Microcontrollers and Processors Handbook Volume I (Order No 270645) and Application Note AP-252 (Embedded Applications Handbook Order No 270648) ‘‘Designing with the 80C51BH’’ 6 |
Ähnliche Teilenummer - 8XC51R |
|
Ähnliche Beschreibung - 8XC51R |
|
|
Link URL |
Privatsphäre und Datenschutz |
ALLDATASHEETDE.COM |
War ALLDATASHEET hilfreich? [ DONATE ] |
Über Alldatasheet | Werbung | Kontakt | Privatsphäre und Datenschutz | Linktausch | Hersteller All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |