nrf frequency channel setup

Wireless & IoT
1

Hi all

Can someone expalin me how does setup of frequency channel works ? As it is written in datasheet F0 = 2400 + RF_CH, where RF_CH is set by writing 6 bites to RF_CH register, and step is 1 MHz, and max frequency is 2,525 GHz. So if we have 6 bits, it means that we can increase channel by adding 1 to RF_CH (from 000000b to 111111b) ? And the main thing : the max increased value is 64 - so how can i gain 2,525 Ghz if max value of reg is 64 (isn’t it mean that writing 111111b to that register we got 2,464 Ghz ? )

Thank You in advance for explaination.

setting up freq from datasheet :

6.3 RF channel frequency

The RF channel frequency determines the center of the channel used by

the nRF24L01. The channel

occupies a bandwidth of 1MHz at 1Mbps and 2MHz at 2Mbps. nRF24L01 can operate on frequencies from

2.400GHz to 2.525GHz. The resolution of the RF channel frequency setting is 1MHz.

At 2Mbps the channel occupies a bandwidth wider than the resolution of the RF channel frequency setting.

To ensure non-overlapping channels in 2Mbps mode, the channel spacing must be 2MHz or more. At

1Mbps the channel bandwidth is the same as the resolution of the RF frequency setting.

The RF channel frequency is set by the RF_CH register according to the following formula:

F0= 2400 + RF_CH [MHz]

A transmitter and a receiver must be programmed with the same RF channel frequency to be able to communicate

with each other.

2

The RF_CH field is 7 bits wide, not 6. See p. 54 of the datasheet. This would allow you to get up to 2.4 GHz + (127 * 1 MHz) = 2.527 GHz. One thing to make sure of (as it says in the datasheet) is that if you are going to have 24L01’s running on different channels near each other, you need to allow 2 MHz of cushion between channels (or 2 LSBs of the RF_CH field).

3

aaaa yes you’re right, my mistake :slight_smile:

thx for expalination