Decoding IR-signals, what is the best approach?

RE: Decoding IR-signals, what is the best approach?

Tushar — Tue, 13 Sep 2016 05:01:55 GMT

Hi All, I also managed to implement infrared sending thanks to the ble_app_uart_IR.zip-example that Torbjørn Øvrebekk made available in this post. Is it running to 38Khz frequency ? Because data I am getting is correct receiver side, still I am not able to act on IR device correctly.Please help me out. Thanks. Also please tell how to change frequency with change of prescaler with IR_CARRIER_LOW_US & IR_CARRIER_HIGH_US value.

RE: Decoding IR-signals, what is the best approach?

Martin Sivertsen — Tue, 12 Jul 2016 08:41:42 GMT

Thank you. We managed to create a decoder using the frequency_counter-example from this post and modifying it.

RE: Decoding IR-signals, what is the best approach?

Øyvind Karlsen — Fri, 08 Jul 2016 10:28:13 GMT

Hi,

In general your receiver circuit will filter out the 38 kHz (or so) pulse, so what is left is detecting the digital signal.

On the nRF52 you have access to two timers, one based on the HFCLK called TIMER and one based on the LFCLK called RTC or App timer. The LFCLK is the more energy efficient of the two.

For the applciation timer we have a tutorial available here.

In this post you can find some simple code on using PPI and TIMER to generate constant 4 MHz output.

Essentially you need to:

Trigger/start a timer on positive edge
Read the timer on negative edge
Decode the information in accordance with the IR protocol

The most energy efficient way of doing this is using the RTC (possibly through app timer) along with PPI. Consult the infocenter on PPI and RTC.

Best regards,

Øyvind