TC1796
Peripheral Units (Vol. 2 of 2)
General Purpose Timer Array (GPTA)
User’s Manual 24-38 V2.0, 2007-07
GPTA, V2.0
Each of the two GT modules provides the following input/output signals:
• Eight clock inputs, connected to the clock bus from the clock distribution unit (CDU)
• Global timer value bus GTVk (outputs), carrying the 24-bit GTk counter value
• TEVk output, indicating a GT counter update
• TGEk output, indicating the result of a compare operation
• SQTk service request output, triggered at a timer overflow.
The Global Timer output signals GTVk, TEVk, and TGEk are available as input signals
at each GTC (see also Page 24-56).
Global timer k can be initialized with a start value, that is written by software into the
GTTIMk register. The 24-bit Global Timer value GTTIMk.TIM is incremented by each
rising edge of clock input signal TEVk that is selected from the 8-bit clock bus via bit field
GTCTRk.MUX. On a Global Timer overflow (transition of FFFFFF
H
to 000000
H
), the
following events occur:
• The 24-bit reload value GTREVk.REV is copied into GTTIMk.TIM
• Bit SRSC0.GT0k is set
• The service request output SQTk is activated (if enabled by bit GTCTRk.REN)
A free-running timer is configured by programming GTREVk.REV with 000000
H
.
The “Timer Event” (TEVk) output is activated if the GTk value changes because of a
clock edge, a timer reload operation, or a software write access to GTCTRk. The TEVk
output is connected to all GTCs. TEVk is used in the GTCs to trigger a compare
operation, re-checking the equality of their compare register contents and the updated
Global Timer value.
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