RF24L01P: Cannot write/read control registers

Wireless & IoT
1

Hi all,

I am new to RF24L01.

Currently, I want to test writing and reading back some values of control register through SPI bus.

The problem is only the first read back after writing a new value to a register returns the expected value.

For example:

  • I write 0 to CONFIG register

  • Then I read back => it is 0 which is OK

  • Then I read more => it becomes 0x08 which is the default value of CONFIG register

  • I try to read more => it is always 0x08 !!!

  • Then I try to re-write 0 to it => read back 0 but subsequent readings still return 0x08 !!!

I try to write/read other register, the result is the same !!!

Could anyone help me to figure out what is the reason for my problem?

Thanks,

Huy

2

Did you set the CE line low prior to writing the register?

Those nRF24L01+ have a lot going on. I’m only just starting to understand all they can do.

I do remember reading that the CE pin needs to be set low when writing to some registers.

3

I think CE line is just to turn on/off radio part of the chip.

FYI, I write an application for the MCU to read/write its registers, the application worked well with a RF24L01 module I bought from a shop, but it could not write to RF24L01 module that I made myself.

Therefore, I think it is not related to firmware but because of a problem in hardware. However, I cannot find out what it is after measuring all pins in the board, replace another chip, etc.

4

khachuy:
I think CE line is just to turn on/off radio part of the chip.

I think you are correct. I tried to find the information about the CE line needing to be low to write registers and I found I had misunderstood the datasheet previously (there’s a lot of information to keep straight in that datasheet).

Thank you for the correction.

If you want to try your code with a different module, you could use one of these cheap boards.

http://www.ebay.com/itm/ws/eBayISAPI.dl … OU:US:1123

I’ve used these boards many times and most of them work well (I have received a couple that didn’t work). What’s nice about these modules is the price. They cost less the $2.50.

5

Hi,

I bought a module of RF24L01 from a local shop and work with it smoothly.

Just because I want to build it myself so that next time I can integrate it to an application board.

Perhaps I will try one more time :slight_smile: (I already tried 4 times but got the same result !!!)