Digi NS9215 Benutzerhandbuch

. . . . .

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.

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.

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.

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