When the TX_ADDRESS of the receiver nRF905 is 0x55, 0xA5, and 0xFF, only the data cannot be received.

RE: When the TX_ADDRESS of the receiver nRF905 is 0x55, 0xA5, and 0xFF, only the data cannot be received.

Kenneth — Thu, 15 Aug 2019 10:54:11 GMT

The only intention of the preamble is for the radio front-end to "lock on" the modulated carrier, it's not part of the received packet that is decoded by the application or radio. It's added automatically by hardware before packet transmission, this ensure that the the receiver to successfully demodulate the address, data and crc.

You may in your case also look into the design of the nRF905, to make sure you have in great detail follow the schematic and layout (with same clearance, cut-out, vias, matching etc). Verify the layout is working as intended by measure the carrier and output power on a spectrum analyzer.

We don't have any other product for the sub 1GHz no.

RE: When the TX_ADDRESS of the receiver nRF905 is 0x55, 0xA5, and 0xFF, only the data cannot be received.

LiAMI — Thu, 15 Aug 2019 08:11:43 GMT

Thank you for your reply. I have enabled the 2byte CRC. I have read back the contents of the RF Config register when the device is in the receiving state. There is no problem, but the situation that 0x55 and 0xA5 cannot be received still exists. I will not use these two addresses for the time being. RX_ADDRESS value, do you have other better similar chip models that do not have address restrictions?
In addition, can you explain in detail how the data packet identification is implemented when nRF905 receives data, for example, how is the preamble and address removed after the CRC check is completed? If the address error is set to 0x55 (01010101), will it Is it recognized as the preamble, caused to be removed and lose the packet ?

RE: When the TX_ADDRESS of the receiver nRF905 is 0x55, 0xA5, and 0xFF, only the data cannot be received.

Kenneth — Wed, 14 Aug 2019 11:18:07 GMT

In general using address bytes of AA and 55 can be problematic since it resemble the preamble, using 00 and FF is a bad idea since it occurs frequently in random demodulated noise. So try to avoid those 4 bytes in your address (especially as the first byte).

Also I recommend to enable 2byte CRC instead of 1byte CRC. You may consider readback all 9 bytes in the RF Config register to verify all are set as expected.

Best regards,
Kenneth