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GMS81C2112 Datasheet(PDF) 82 Page - Hynix Semiconductor |
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GMS81C2112 Datasheet(HTML) 82 Page - Hynix Semiconductor |
82 / 107 page ![]() GMS81C2112/GMS81C2120 76 JUNE. 2001 Ver 1.00 Release the Wake-up Timer mode The exit from Wake-up Timer mode is hardware reset, Timer0 overflow or external interrupt. Reset re-defines all the Control registers but does not change the on-chip RAM. External interrupts and Timer0 overflow allow both on-chip RAM and Control registers to retain their values. If I-flag = 1, the normal interrupt response takes place. If I- flag = 0, the chip will resume execution starting with the instruction following the STOP instruction. It will not vec- tor to interrupt service routine.(refer to Figure 17-1) When exit from Wake-up Timer mode by external inter- rupt or timer0 overflow, the oscillation stabilization time is not required to normal operation. Because this mode do not stop the on-chip oscillator shown as Figure 17-4. Figure 17-4 Wake-up Timer Mode Releasing by External Interrupt or Timer0 Interrupt 17.4 Internal RC-Oscillated Watchdog Timer Mode In the Internal RC-Oscillated Watchdog Timer mode, the on-chip oscillator is stopped. But internal RC oscillation circuit is oscillated in this mode. The on-chip RAM and Control registers are held. The port pins out the values held by their respective port data register, port direction regis- ters. The Internal RC-Oscillated Watchdog Timer mode is activated by execution of STOP instruction after set- ting the bit WAKEUP and RCWDT of CKCTLR to " 01 ". (This register should be written by byte operation. If this register is set by bit manipulation instruction, for example "set1" or "clr1" instruction, it may be unde- sired operation) Note: Caution: After STOP instruction, at least two or more NOP instruction should be written Ex) LDM WDTR,#1111_1111B LDM CKCTLR,#0010_1110B STOP NOP NOP The exit from Internal RC-Oscillated Watchdog Timer mode is hardware reset or external interrupt. Reset re-de- fines all the Control registers but does not change the on- chip RAM. External interrupts allow both on-chip RAM and Control registers to retain their values. If I-flag = 1, the normal interrupt response takes place. In this case, if the bit WDTON of CKCTLR is set to "0" and the bit WDTE of IENH is set to "1", the device will execute the watchdog timer interrupt service routine.(Figure 17-5) However, if the bit WDTON of CKCTLR is set to "1", the device will generate the internal RESET signal and exe- cute the reset processing. (Figure 17-6) If I-flag = 0, the chip will resume execution starting with the instruction following the STOP instruction. It will not vector to interrupt service routine.(refer to Figure 17-1) When exit from Internal RC-Oscillated Watchdog Timer mode by external interrupt, the oscillation stabilization time is required to normal operation. Figure 17-5 shows the timing diagram. When release the Internal RC-Oscil- lated Watchdog Timer mode, the basic interval timer is ac- tivated on wake-up. It is increased from 00H until FFH. The count overflow is set to start normal operation. Therefore, before STOP instruction, user must be set its relevant pres- caler divide ratio to have long enough time (more than 20msec). This guarantees that oscillator has started and stabilized. By reset, exit from internal RC-Oscillated Watchdog Tim- er mode is shown in Figure 17-6. Wake-up Timer Mode Oscillator (XI pin) STOP Instruction Normal Operation Normal Operation CPU Clock Request Interrupt Execution Do not need Stabilization Time ( stop the CPU clock ) |