 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
HT86XXX Datasheet(PDF) 24 Page - Holtek Semiconductor Inc |
|
|
|||||||||||||||||||||||||||||
HT86XXX Datasheet(HTML) 24 Page - Holtek Semiconductor Inc |
|
|
24 / 55 page  HT86XXX Rev. 1.90 24 January 11, 2007 Oscillator Configuration The HT86XXX provides two types of oscillator circuit for the system clock, i.e., RC oscillator and crystal oscilla- tor. No matter what type of oscillator, the signal is used for the system clock. The HALT mode stops the system oscillator and ignores external signal to conserve power. If the RC oscillator is used, an external resistor between OSC1 and VSS is required, and the range of the resis- tance should be from 30k W to 680kW. The system clock, divided by 4, is available on OSC2 with pull-high resis- tor, which can be used to synchronize external logic. The RC oscillator provides the most cost effective solu- tion. However, the frequency of the oscillation may vary with VDD, temperature, and the chip itself due to pro- cess variations. It is therefore not suitable for timing sen- sitive operations where accurate oscillator frequency is desired. On the other hand, if the crystal oscillator is selected, a crystal across OSC1 and OSC2 is needed to provide the feedback and phase shift required for the oscillator, and no other external components are required. A resonator may be connected between OSC1 and OSC2 to replace the crystal and to get a frequency reference, but two ex- ternal capacitors in OSC1 and OSC2 are required. There is another oscillator circuit designed for Timer3 ¢s clock source as the RTC time base which is determined by mask option. If the mask option determines that Timer3 ¢s clock source is from a 32kHz crystal, then a 32kHz crystal should be connected to XIN and XOUT. Watchdog Timer - WDT The WDT clock source is implemented by a dedicated RC oscillator (WDT oscillator) or instruction clock (sys- tem clock divided by 4), decided by mask options. This timer is designed to prevent a software malfunction or sequence jumping to an unknown location with unpre- dictable results. The Watchdog Timer can be disabled C r y s t a l O s c i l l a t o r R C O s c i l l a t o r O S C 1 O S C 2 O S C 2 f S Y S / 4 O S C 1 V D D R T C O s c i l l a t o r X O U T X I N ( P C 6 ) System Oscillator S y s t e m C l o c k / 4 8 - b i t C o u n t e r W D T P r e s c a l e r 7 - b i t C o u n t e r 8 - t o - 1 M U X W D T T i m e - o u t W S 0 ~ W S 2 M a s k O p t i o n S e l e c t W D T O S C Watchdog Timer Bit No. Label Function 0 EMI Controls the master (global) interrupt (1= enabled; 0= disabled) 1 EEI Controls the external interrupt (1= enabled; 0= disabled) 2 ET0I Controls the Timer 0 interrupt (1= enabled; 0= disabled) 3 ET1I Controls the Timer 1 interrupt (1= enabled; 0= disabled) 4 EIF External interrupt request flag (1= active; 0= inactive) 5 T0F Timer 0 request flag (1= active; 0= inactive) 6 T1F Timer 1 request flag (1= active; 0= inactive) 7 ¾ Unused bit, read as ²0² INTC (0BH) Register Bit No. Label Function 0 ET2I Controls the Timer 2 interrupt (1= enabled; 0= disabled) 1 ET3I Controls the Timer 3 interrupt (1= enabled; 0= disabled) 2~3, 6~7 ¾ Unused bit, read as ²0² 4 T2F Timer 2 interrupt request flag (1= active; 0= inactive) 5 T3F Timer 3 interrupt request flag (1= active; 0= inactive) INTCH (1EH) 1 Register |
|
Link URL |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link to Datasheet | Link Exchange | Manufacturer List 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
