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S Y S T E M C O N T R O L M O D U L E
General purpose timers/counters
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G e n e r a l p u r p o s e t i m e r s / c o u n t e r s
Ten 32-bit general purpose timers/counters (GPTC) provide programmable time
intervals to the CPU when used as one or multiple timers. There are two I/O pins
associated with each timer.
When used as a gated timer, one I/O pin serves as an input qualifier (high/low
programmable).
When used as a regular timer (enabled by software), the other I/O pin serves
as a terminal count indicator output.
These pins can also be used independently as up/down counters to monitor the
frequency of certain events (events capturing). In this situation, the I/O pin
becomes the clock source of the counter.
Source clock
frequency
Depending on the applications, the source clock frequency of the timers/counters is
selectable among the system memory clock, the system memory clock with multiple
divisor options, or an external pulse event. The divisor options are 2, 4, 6, 16, 32, 62,
128, or 256. If an external pulse is used, the frequency must be less than one half the
system memory clock frequency.
GPTC
characteristics
Each GPTC can measure external event lengths up to minutes range, and can
be individually enabled/disabled.
Each GPTC can be configured to reload, with the value defined in the Initial
Timer Count register (one for each GPTC), and generates an interrupt upon
terminal count.
Each GPTC has an interrupt request connected to the IRQ interrupt controller
(VIC). The priority level and enable/disable of each interrupt can be
programmed in the VIC. The CPU can read the contents of the timer/counter.
GPTCs can be concatenated to form larger timer counters.
Control field
Include this control field in each of the 32-bit timer/counter control registers:
Clock frequency selection
Mode of operation:
–
Internal timer, with or without external terminal count indicator
–
External gated timer with gate active low
–
External gated timer with gate active high
–
External event counter — frequency must be less than one half the system
memory clock frequency
Timer/counter enable
Count up or down
Summary of Contents for NS9215
Page 1: ...NS9215 Hardware Reference 90000847_C Release date 10 April 2008...
Page 3: ......
Page 4: ......
Page 26: ...26 Hardware Reference NS9215...
Page 44: ...P I N O U T 26 5 System clock 44 Hardware Reference NS9215 System clock drawing...
Page 52: ...P I N O U T 26 5 Power and ground 52 Hardware Reference NS9215...
Page 80: ...I O C O N T ROL M O D U L E Memory Bus Configuration register 80 Hardware Reference NS9215...
Page 136: ...WOR KI N G W I TH T H E C P U Noncachable instruction fetches 136 Hardware Reference NS9215...
Page 202: ...S Y S T E M C O N T RO L M OD U L E RTC Module Control register 202 Hardware Reference NS9215...
Page 354: ...E X T E R N A L D M A DMA Peripheral Chip Select register 354 Hardware Reference NS9215...
Page 472: ...R E A L TI M E C L O C K M O D U L E General Status register 472 Hardware Reference NS9215...
Page 512: ...TI M I NG Clock timing 512 Hardware Reference NS9215...
Page 515: ...PA CKA GING Processor Dimensions www digiembedded com 515...
Page 516: ...PA CKA GING Processor Dimensions 516 Hardware Reference NS9215...