Rainbow Electronics T89C51CC02 - Manual (Page 54)

54 Rev.A - May 17, 2001
Preliminary
T89C51CC02
12.4.2. Mode 1 (16-bit Timer)
Mode 1 configures Timer 1 as a 16-bit Timer with TH1 and TL1 registers connected in cascade (see Figure 35).
The selected input increments TL1 register.
12.4.3. Mode 2 (8-bit Timer with Auto-Reload)
Mode 2 configures Timer 1 as an 8-bit Timer (TL1 register) with automatic reload from TH1 register on overflow
(see Figure 36). TL1 overflow sets TF1 flag in TCON register and reloads TL1 with the contents of TH1, which
is preset by software. The reload leaves TH1 unchanged.
12.4.4. Mode 3 (Halt)
Placing Timer 1 in mode 3 causes it to halt and hold its count. This can be used to halt Timer 1 when TR1 run
control bit is not available i.e. when Timer 0 is in mode 3.
12.5. Interrupt
Each Timer handles one interrupt source that is the timer overflow flag TF0 or TF1. This flag is set every time
an overflow occurs. Flags are cleared when vectoring to the Timer interrupt routine. Interrupts are enabled by
setting ETx bit in IEN0 register. This assumes interrupts are globally enabled by setting EA bit in IEN0 register.
Figure 38. Timer Interrupt System
TF0
TCON.5
ET0
IEN0.1
Timer 0
Interrupt Request
TF1
TCON.7
ET1
IEN0.3
Timer 1
Interrupt Request