Hi
We've used DA14683 to receive various advertisement packets, sometimes it works well with very low CRC error rate, however, sometimes it almost can’t work because of too many CRC errors.
We’ve done some tests, and found the error rate is high depend on the content of packets, for example, in direct test mode(SmartSnippets Toolbox v5.0.10.2434, two USB develop kit with latest plt_fw.bin), set payload to “All 0s” or “All 1s”, the receiver can’t receive packets without CRC error, if set payload to 00001111, the receiver can receive packets with low CRC error rate, please see attachment.
In fact, in normal mode, if set last 31 bytes of packet to 0x75,0x31,0x11,0x48,0x96,0x77,0xF8,0xE3,0x46,0xE9,0xAB,0xD0,0x9E,0x53,0x33,0xD8,0xBA,0x98,0x08,0x24,0xCB,0x3B,0xFC,0x71,0xA3,0xF4,0x55,0x68,0xCF,0xA9,0x19 (after with 37 channel whitening, all is 0x00 in air) or 0x75,0x31,0xEE,0xB7,0x69,0x88,0x07,0x1C,0xB9,0x16,0x54,0x2F,0x61,0xAC,0xCC,0x27,0x45,0x67,0xF7,0xDB,0x34,0xC4,0x03,0x8E,0x5C,0x0B,0xAA,0x97,0x30,0x56,0xE6 (after with 37 channel whitening, all is 0xFF in air), the receiver can’t receive packets without CRC error too.
Would you give us some suggestions?
Best regards,
Peter
Hi Peter,Thank you for posting your question online.I have created an internal ticket and I will get back to you as soon as possible.Best Regards,OV_Renesas
Hi Peter,The 'all 1's' and 'all 0's' are special payloads, not used for DTM RF testing.Payloads for DTM RF testing are limited to '11110000' (for RF TX dF1), '10101010' (for RF TX dF2) or 'PRBS9' (e.g for RF RX sensitivity tests). When using the 'all 1's' and 'all 0's' the receiver will start drifting (because of internal DC offset), and the CRC errors will increase. It constantly will be at about -250 KHz or +250 KHz offset from center frequency = > resulting in frequency drift. Probably one could avoid this by disabling the AFC, but that's not supported (AFC is needed for normal, practical use-cases). BLE modulation: '0' and '1' : Using e.g. '10101010' or 'PRBS9' will not cause an offset (the mean value is near the center frequency). Hope this clarifies the situation. Best Regards,OV_Renesas
Hi OV_Renesas,
Thanks for so quick and so detailed answer!
Best Regards,
Hi Peter,Thank you for the reply.FYI: from Bluetooth Low Energy Handbook: Best Regards,OV_Renesas
The information is very useful!
Thank you so much!