PixArt Imaging Inc.

PAC107

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PixArt Imaging Inc.

V1.4, Aug, 2005

modes 0,1 and 2 are same as Timer 0. Timer 1’s mode 3 is a hold-count mode.

Timer 1 is controlled by high-nibble of the TMOD register and bits 7,6,3,and 2 of the

TCON register. TMOD selects the method of timer gating (GATE), timer or counter

overflow flag (TF1),run control (TR1),interrupt flag(IE1), and interrupt type control (IT1).

For normal timer operation (GATE = 0), setting TR1 allows timer register TL1 to be

incremented by the selected input. Setting GATE and TR1 allows external pin

1

INT

to

control timer operation. This setup can be used to make pulse width measurements.

Timer 1/ Mode 0 (13-bit Timer)

Mode 0 configures timer 0 as a 13-bit timer, which is set up as an 8-bit timer (TH1 register)

with a modulo-32 prescalar implemented with the lower 5 bits of the TL1 register. The

upper 3 bits of the TL1 register are ignored. Prescalar overflow increment the TH1 register.

Timer1/ Mode 1 (16-bit Timer)

Mode 1 configures timer 1 as a16-bit timer with TH1 and TL1 connected in cascade. The

selected input increments TL1.

Timer 1/ Mode 2 (8-bit Timer)

Mode 2 configures timer 1 as an 8-bit timer (TL1 register) with automatic reload from the

TH1 register on overflow. Overflow from TL1 sets overflow flag TF1 in the TCON register

and reloads TL1 with the contents of TH1, which is preset by software. The reload leaves

TH1 unchanged.

Timer 1/ Mode3 (Halt)

Placing timer in mode 3 causes it to halt and its count. This can be used to halt timer 1

when the TR1 run control bit is not available, i.e., when timer 0 is in mode 3.

Timer 2

Timer 2 is a 16-bit timer/count constructed by {TH2, TL2}. The mode control T2MOD and

the configure T2CON control the operation of timer 2.

Operating modes:

capture mode,

auto-reload mode, (default)

baud rate generator mode,

programmable clock-out mode.