Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 17 of 90 The authors reserve the right to change specifications without notice. 4.2.2 Major data frame version (Major bit field) 484 485 Major Description 00 LoRaWAN R1 01..11 RFU Table 5: Major list 486 487 The Major version specifies the format of the frames exchanged in the Join procedure (see 488 Section 6.2.4) and the first four octets of the MACPayload as described in Section 4. For 489 each Major version, end-devices MAY implement different Minor versions of the frame format. 490 The Minor version used by an end-device SHALL be made known to the Network Server 491 beforehand using out-of-band communication (e.g., as part of the end-device personalization 492 information). 493 4.3 MAC Payload of Data Frames (MACPayload) 494 The MAC payload of data frames contains a frame header (FHDR) followed by an OPTIONAL 495 port field (FPort) and an OPTIONAL frame payload field (FRMPayload). 496 A frame with a valid FHDR, no FOpts (FOptsLen=0), no FPort and no FRMPayload is 497 a valid frame. 498 4.3.1 Frame header (FHDR) 499 An FHDR contains the short end-device address (DevAddr), a frame control octet (FCtrl), 500 a 2-octet frame counter (FCnt), and up to 15 octets of frame options (FOpts) to transport 501 MAC commands. 502 503 Size (octets) 4 1 2 0..15 FHDR DevAddr FCtrl FCnt FOpts Table 6: FHDR format 504 505 506 For downlink frames, the FCtrl content of the frame header is 507 508 Bits 7 6 5 4 [3..0] FCtrl ADR RFU ACK FPending FOptsLen Table 7: FCtrl downlink frames format 509 510 511 512