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HT82M9BE Folha de dados(PDF) 14 Page - Holtek Semiconductor Inc |
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HT82M9BE Folha de dados(HTML) 14 Page - Holtek Semiconductor Inc |
14 / 44 page HT82M9BE/HT82M9BA Rev. 1.80 14 December 22, 2008 There are 3 registers related to Timer/Event Counter 1; TMR1H (0FH), TMR1L (10H), TMR1C (11H). Writing TMR1L will only put the written data to an internal lower-order byte buffer (8 bits) and writing TMR1H will transfer the specified data and the contents of the lower-order byte buffer to TMR1H and TMR1L preload registers, respectively. The Timer/Event Counter 1 preload register is changed by each writing TMR1H op- erations. Reading TMR1H will latch the contents of TMR1H and TMR1L counters to the destination and the lower-order byte buffer, respectively. Reading the TMR1L will read the contents of the lower-order byte buffer. The TMR1C is the Timer/Event Counter 1 control register, which defines the operating mode, counting en- able or disable and active edge. The TM0, TM1 bits define the operating mode. The event count mode is used to count external events, which means the clock source comes from an external (TMR0/TMR1) pin. The timer mode functions as a nor- mal timer with the clock source coming from the fSYS/4 (Timer0/Timer1). The pulse width measurement mode can be used to count the high or low level duration of the external signal (TMR0/TMR1). The counting is based on the fSYS/4 (Timer0/Timer1). In the event count or timer mode, once the Timer/Event Counter 0/1 starts counting, it will count from the current contents in the Timer/Event Counter 0/1 to FFH or FFFFH. Once overflow occurs, the counter is reloaded from the Timer/Event Counter 0/1 preload register and generates the interrupt request flag (T0F/T1F; bit 5/6 of INTC) at the same time. In the pulse width measurement mode with the TON and TE bits equal to one, once the TMR0/TMR1 has re- ceived a transient from low to high (or high to low if the TE bits is ²0²) it will start counting until the TMR0/TMR1 returns to the original level and resets the TON. The measured result will remain in the Timer/Event Counter 0/1 even if the activated transient occurs again. In other words, only one cycle measurement can be done. Until setting the TON, the cycle measurement will function again as long as it receives further transient pulse. Note that, in this operating mode, the Timer/Event Counter 0/1 starts counting not according to the logic level but according to the transient edges. In the case of counter overflows, the counter 0/1 is reloaded from the Timer/Event Counter 0/1 preload register and issues the interrupt request just like the other two modes. To en- able the counting operation, the timer ON bit (TON; bit 4 of TMR0C/TMR1C) should be set to 1. In the pulse width measurement mode, the TON will be cleared automati- cally after the measurement cycle is completed. But in the other two modes the TON can only be reset by in- structions. The overflow of the Timer/Event Counter 0/1 is one of the wake-up sources. No matter what the oper- ation mode is, writing a 0 to ET0I/ET1I can disable the corresponding interrupt services. In the case of Timer/Event Counter 0/1 OFF condition, writing data to the Timer/Event Counter 0/1 preload regis- ter will also reload that data to the Timer/Event Counter 0/1. But if the Timer/Event Counter 0/1 is turned on, data written to it will only be kept in the Timer/Event Counter 0/1 preload register. The Timer/Event Counter 0/1 will still Bit No. Label Function 0~2, 5 ¾ Unused bit, read as ²0² 3TE To define the TMR0 active edge of Timer/Event Counter 0 (0=active on low to high; 1=active on high to low) 4 TON To enable/disable timer 0 counting (0=disabled; 1=enabled) 6 7 TM0 TM1 To define the operating mode 01=Event count mode (external clock) 10=Timer mode (internal clock) 11=Pulse width measurement mode 00=Unused TMR0C (0EH) Register Bit No. Label Function 0~2, 5 ¾ Unused bit, read as ²0² 3TE To define the TMR1 active edge of Timer/Event Counter 1 (0=active on low to high; 1=active on high to low) 4 TON To enable/disable timer 1 counting (0=disabled; 1=enabled) 6 7 TM0 TM1 To define the operating mode 01=Event count mode (external clock) 10=Timer mode (internal clock) 11=Pulse width measurement mode 00=Unused TMR1C (11H) Register |
Nº de peça semelhante - HT82M9BE_08 |
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Descrição semelhante - HT82M9BE_08 |
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