HI, I recently used nRF905, a one-to-many intercommunication project, because one-to-many will send corresponding instructions for machines with different serial numbers, and need multiple receiving addresses (default is 0xE7). When I set to 0x55 as the receiving address, And other settings are as follows. It is found that devices with receiving addresses of 0x55 (01010101), 0xA5 (10100101), and 0xFF (11111111) can normally send data to other receiving devices and receive them, but other devices have these three values. When sending data for the device receiving the address, you can see that the carrier detect (CD) and address check (AM) pins are set high through the circuit, but you can't read the data, hope to answer, thank you!
// define nRF905 configration register .#define nRF905_CONFIG_REG_0 0x6A #define nRF905_CONFIG_REG_1 0x0C #define nRF905_CONFIG_REG_2 0x44 #define nRF905_CONFIG_REG_3 0x20 #define nRF905_CONFIG_REG_4 0X20 #define nRF905_ADDRESS_REG_0 0xE7 // 0x55 or 0xA5 or 0xFFcannot be received.#define nRF905_ADDRESS_REG_1 0xE7 // 0x55 or 0xA5 or 0xFFcannot be received.#define nRF905_ADDRESS_REG_2 0xE7 // 0x55 or 0xA5 or 0xFFcannot be received.#define nRF905_ADDRESS_REG_3 0xE7 // 0x55 or 0xA5 or 0xFFcannot be received.#define nRF905_CONFIG_REG_9 0x58
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.
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.