nRF24L01RF datasheet contradiction?

[Radian]

The nRF24L01 dataseet V2 (the most recent I think?) states (p.23) that the nRF24L01 can operate on frequencies from 2.400GHz to 2.525GHz . The channel steps are stated as being 1MHz for the RF_CH parameter - but the register map table (p.64) gives bits 6:0 to this value with bit 7 reserved (in the data sheet it actually gives 6:0 0000010 as the reset value as well as 0 for bit 7 just to confuse things a little further).

2.525GHz would require a value of 125 for RF_CH but this isn't permitted according to the description in the register map. Empirically, I discovered that the highest value that results in correct operation is 62 for the samples I have. Is this what I should expect to get and therefore the true frequency range is more like 2.400GHz to 2.462GHz?

[Asbjørn]

No, the chips radio is built for operation up to 2.525 GHz as some countries allows for use up to this. The world wide ISM band is between 2.400 GHz and 2.480 GHz. The recommendation is to stay within the ISM band in order to be able to sell your product across the world.

I'm not sure what you are writing to the chip, but you should be able to use all these channels. May I ask what you have tested since you see a restriction to channel 62.

[Radian]

Thanks for your reply. I have obtained another set of modules now from a different supplier and the full range of frequencies now work as you describe. I suspect that the other modules had an inferior layout using the earlier version of the chip.

I'm now working with nRF24L01+ but the datasheet (nRF24L01P_Product_Specification_1_0 page 58) still describes RF_CH as a 6-bit field with bit 7 reserved ...

05 RF_CH RF Channel Reserved 7 0 R/W Only '0' allowed RF_CH 6:0 0000010 R/W Sets the frequency channel nRF24L01+ operates on

Can I safely ignore the instruction that only 0 is allowed in bit 7?

[Asbjørn]

I can't say safely as you have to test and make sure you're not breaking any regulatory requirements with your application. Functionality wise on the chip, you should be able to utilize the full range of frequencies.

[Radian]

Asbjørn, I do understand that passing regulatory requirements is my responsibility. By "safely" I refer to the contradiction between the observation that channel values of 64 to 125 do appear to work while the datasheet tells me to only program a channel value of 63 or less.

Do you therefore agree that we can Answer my opening query: "nRF24L01RF datasheet contradiction?" in the affirmative? As a diligent application engineer I am bound to take heed of all instructions given by product manufacturers including any errata.

[Asbjørn]

I do see your point and the contradiction you point out. I just wanted to clarify why we have chosen to "hide" it.