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5.6 Counter/timer
RT-DAC/USB2 contains two 32-bit timer/counter channels. Both counter/timer channels can operate either
in the counter or timer modes. In the timer mode the timer/counter channels count pulses of the internal board
clock. The frequency of the clock corresponds to the board version (20 MHz is the default frequency value).
In the counter mode the timer/counter channels count external pulses respectively from the CNT0 and CNT1
inputs. In the timer mode the blocks does not use any external signals.
In the counter mode the counter inputs are named: DIO24/CNT0 and DIO25/CNT1 and are located at the
CN1 connector at pins 35 and 36. The inputs of the counters CTN0 and CNT1 are shared with the general
purpose digital I/Os DIO24 and DIO25. If the DIO24/CNT0 or DIO25/CNT1 signals are defined to be the
inputs, their states can be read (typically as the digital inputs) and simultaneously they excite the respective
counter block. If the signals are set to be outputs, their states are determined by software (typically as the
digital outputs) and simultaneously they excite the respective counter block (this operating mode can be
applied to test the blocks in a programming manner).
The configuration of the timer/counter block is shown below. The Mode flag selects between counter and
time modes. The Reset flag is applied to reset the counter. 32-bit counter stores a number of the internal
clock periods or a number of the external pulses (the rising edges of the pulses are counted).
Reset
Cnt
0
Counter
40 MHz
1
Internal Clock
Mode
I/O signal
Parameter
Fig. 5.8. Configuration of the timer/counter block
In the C language interface the features of the channels are controlled by the TmrCntType structure. The
main structure contains the array:
TmrCntType
TmrCnt[ 2 ];
that is applied to communicate with the timer/counter blocks
In the .NET interface the state of the timer/counter blocks are described in the dedicated TmrCntClass
class.
5.6.1 Mode
C interface
.NET interface
Simulink interface
unsigned int Mode
TmrCntClass.ModeState Mode
TmrCntMode
output of the read S-function
SetTmrCntMode
input of the send S-function
DESCRIPTION
The field sets/means the operating mode of the timer/counter.
In the C and Simulink interfaces the value equal to 0 sets/means the counter mode; the value equal
to 1 means the timer mode.
In the .NET interface the value equal to CounterMode sets/means the counter mode; TimerMode
means that the block operates as a timer.
RT-DAC/USB2 - User’s Manual
page 31