Is it feasible to regard the 'Analog in' resources of RT-BOX as the extra 'Digital in' resources?

Question

Dear specialist:

    I am using the RT-BOX1 instead of RT-BOX3 ,but my project need more than 16 PWM intake resources, so is it feasible to regard 'Analog in' as the PWM capture resources???  Should I set a voltage threshold at a certain value to realize the PWM signal intake? Maybe the analog in resources require more time to capture the PWM signals, but in some cases like controlling thyristors ,I reckon it's totally enough.

    Thank U.

Answer 1

> need more than 16 PWM intake resources

There are 32 digital inputs, but can understand if you're referring to a PWM resource occupying two digital channels.

> so is it feasible to regard 'Analog in' as the PWM capture resources

You can use an Analog In with a comparator like a digital signal. However, there is a difference between using a Digital In and a PWM Capture measurement for a gate signal to a Power Module with a Sub-Cycle Averaged configuration.  There is no Power Module using thyristor components and the thyristors switch at line frequency, so in that particular application the distinction likely isn't significant.

Answer 2

It depends on the frequency of your PWM signal.

The analog in channels are updated once per simulation step. The digital in channels used for the PWM capture blocks are sampled with 7.5 ns.

If the PWM cycle time is much higher than the simulation step time you don't need a PWM capture, a Digital in signal would do as well. In this case you could also use an analog in signal as a replacement.

In all other cases, if you want to use the analog in channels as replacement for the PWM captures you'd have to develop an external circuit that provides an analog voltage output that is proportional to the duty cycle of the PWM signal.

Comments

Thank U so much!!!