gc80c520a CORERIVER Semiconductor, gc80c520a Datasheet - Page 41

• Manufacturer Part Number: gc80c520a
• Description: Midas1.0 Family Mask Rom/eprom/romless 8-bit Turbo Microcontrollers
• Manufacturer: CORERIVER Semiconductor

MiDAS1.0 Family
0000h. The timer overflow flag TFx of the relevant timer is set and an timer interrupt will occur if enabled.
The selection of the time-base in the timer function is the same as Mode 0. The function of GATE bit is
the same as Mode 0.
6.2.4.1.4 Mode 2
In Mode 2, the Timer/Counters operate as 8-bit counters with automatic reload. TLx operates as an 8-bit
counter, while THx holds the reload value. When the TLx register overflows from FFH to 00H, the TFx bit
in TCON is set and TLx is reloaded with the contents of THx, and the counting process continues from
reloaded value. The reload operation leaves the contents of the THx register unchanged. Counting is
enabled when the TRx = 1 and either GATE = 0 or /INTx =1. As in the other two modes 0 and 1, Mode 2
allows counting of either a timer clock (clock/12 or clock/4) or pulses on pin Tx.
6.2.4.1.5 Mode 3
In Mode 3, Timer/Counters 0 and 1 operate differently from each other. Timer/Counter 1 in Mode 3 simply
holds its count. The effect is the same as setting TR1 = 0. Timer/Counter 0 in Mode 3, establishes TL0
and TH0 as two separate 8-bit counters. TL0 uses the Timer/Counter 0 control bits: C/T, GATE, TR0,
/INT0 and TF0. It is determined by C/T (TMOD.2) whether the TL0 can count clock cycles (clock/12 or
clock/4) or 1-to-0 transitions on pin T0. TH0 is locked int a timer function (clock/12 or clock/4) and takes
over the use of TR1 and TF1 from Timer/Counter 1. Mode 3 is used when an extra 8-bit timer is needed.
With Timer 0 in Mode 3, Timer 1 can still be used in Modes 0, 1 and 2. However, it no longer has control
over its overflow flag TF1 and the enable bit TR1. Timer 1 can still be used as a timer/counter and retains
the use of GATE and INT1 pin. In this condition, it can be turned on and off by switching it out of and into
its own Mode 3. It can also be used as a baudrate generator for the UART.
Figure 6-15 illustrates the various operation modes for Timer/Counter 0/1.
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