Cannot init NRF24L01+ registers using SPI and STM32F303

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Am trying to initialize the NRF24L01+ registers using SPI but they always return 0x00.

According to the datasheet, Table 20 on page 51, all write commands will have a pattern of b001x xxxx, which i understood as having a 0x2x pattern.

In my snapshot below, i send the register value, for example register 0x00 will be sent as 0x20 indicating a write command to that register and then i send the value to be written on that register.

As you see on the MISO line, the value is 0x00 even when am trying to write a 0x08 which should be the default value according to page 57 of the datasheet.

I still dont know why its returning 0x00 even when i independently try to read the contents of that register later on without writing to it. I still get 0x00. The same applies to all other registers that am trying to re-init. Anyone who has experienced this behaviour elsewhere or is it me that is having something wrong?

enter image description here enter image description here The NRF24 am trying to program here is this type from sparkfun

spi stm32
1 Answers

You are close. The datasheet shows write register as 001A AAAA and read as 000A AAAA, where the 5 A's represent the register you want to write to. The spec states that while the command is being sent (read, write, read payload, write payload, flush, activate, and so on), the device will return the status register. In your data, the device is responding with 0x0E, which is correct; decoded is is saying no errors and no data received or pending to transmit. If you want to see if the command you send was accepted, you need to first write the data and then read the data. For example, let's say we want to write the config register to enable the device as a receiver, 2 byte CRC with Rx interrupts enabled.
First, you would send 0b00100000 (0x20), 0b00111111 (0x3F). The device will respond with 0b00001110 (0x0e), 0b00000000 (0x00). This is what you are seeing. If you want to verify the configuration register, you need to then send 0b00000000 (0x00),which is the command to read the config register, then 0b00000000 (0x00), which is a dummy byte to clock out the data. The device will respond with 0x0e, which is the status, and then 0x3F assuming you configured as I did above. Note that there are more commands than just reading and writing the registers, there are specific commands to fill and read the pipeline data.

Hope this helps.

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