Microprocessors

1
Microprocessors

• Counters Ch9 continued.

2
TMOD

• Set C/T 1 to configure the timer for
  counting.
• MOV TMOD, 00000110B makes timer0 an 8-bit
  counter.

3
External Connections for Counting
Connect to pin 14 to count with timer 0
Connect to pin 15 to count with timer 1
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TL1 continues to advance with every pulse that
comes in on T1 until TL1 transitions from FFH to
00H. At that time TF1 1. We continue the
analysis with TF1 1.
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Timer Operation C/T 0, Gate 0
If Gate bit is zero, TRx is always anded with 1.
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Counter OperationGate 1 C/T 1
If Gate bit is 1, TRx is anded with INTx. The TR
switch is closed only if both TRx and INTx are
high.
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Counter OperationGate 1, C/T 1
1
IF TRx 1 the counter advances when and only
when INTx 1