Using nRF9151 to build a pulse reader for utility meters

[PeterVeres]

Hello,

I would like to know if the nRF9151 is suitable for building a product that will be able to monitor (read) multiple pulse signals originating in utility meters (electric/power, gas, water...). These pulses are usually provided in as a contact closure signal, with frequency up to 500 MHz. Can the digital inputs of the nRF9151 work in interrupt mode? 

Thank you for any help,

Peter

[Priyanka]

Hi Peter,

The 500MHz sounds high and I am not sure if this is possible. I have inquired internally though to confirm this. 

Can the digital inputs of the nRF9151 work in interrupt mode? 

This should be possible. You can refer to the SAADC documentation of the nRF9151.

Regards,

Priyanka

[Priyanka]

Hi Peter,

The 500MHz is indeed very high. But maybe you could use a frequency divider for the same and then it can be detected by the nRF9151.

-Priyanka

[PeterVeres]

Hello Priyanka,

thank you for your reply. Could you specify what frequency is considered "safe" so that the processor will not skip a beat? 

Peter

[Priyanka]

Hi Peter,

A maximum of 8MHz input signal should be the limit, since the SPI serial interface max clock frequency is 8MHz for both SPIM and SPIS. 

-Priyanka

[PeterVeres]

Oh, sorry, I meant 500Hz signal in the first place my mistake. So that should be ok then, thank you for your reply, I will dig deeper in the SAADC documentation you provided.

[Priyanka]

Ah 500Hz should be fine then

The maximum sampling frequency for the SAADC is also 200kHz.

-Priyanka