Rainbow Electronics AT89C5132 - Manual (Page 54)

54
AT8xC5132
4173A–8051–08/02
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 30). The selected input increments TL1 register.
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 32). 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.
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.
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 36. Timer Interrupt System
TF0
TCON.5
ET0
IEN0.1
Timer 0
Interrupt Request
TF1
TCON.7
ET1
IEN0.3
Timer 1
Interrupt Request