Frequency Meter Type Overview

Overview

The Frequency Meter type is a counter that uses up to 2 fast inputs. Each TM3 HSC expansion module can have up to 2 Frequency Meter type high speed counters configured.

Frequency Meter Type Mode

The Frequency meter counter measures the frequency of events. Frequency is the number of events per second (Hz).

Performance

The maximum counter frequency is determined by the Filter value, used to reduce the bounce effect on the input. The maximum frequency admissible on a fast input is 200 kHz if the bounce filter value is 0.002 ms (the default value).

Configure the bounce filter value according to the frequency applied at the inputs. If the filter value is too high, the input frequency may not be detected and the counter value (CurrentValue output) of the HSCMain_TM3 function block is set to 0.

Refer also to TM3XFHSC202 Input Characteristics and TM3XHSC202 Input Characteristics.

For more information about the bounce filter, refer to Dedicated Features.

Accuracy

The precision of the Frequency meter counter cannot be assumed when the measured frequency falls below a specific minimum value. This minimum value depends on the time base configured, that is, the period of time during which events are counted.

This table shows for each configurable value of Time base the minimum frequency necessary to obtain an accuracy of 0.01 %:

The maximum duty cycle at 200 kHz is 55 %.