Issue link: https://read.uberflip.com/i/1464686
LoRaWAN ® Multi-Package Access Protocol Specification TS007-1.0.0 ©2022 LoRa Alliance ® Page 11 of 15 The authors reserve the right to change specifications without notice. 4.3 Multi-Package Buffer Fragmentation (MultiPackBufferFrag) 297 298 This command is used by the end-device to signal that it is transmitting a fragment of the 299 ANS buffer. The format of the command payload is: 300 301 Size (octets) 1 Variable: 1 to MaxPayloadLen - 3 1 Field BaseByte ANS buffer[BaseByte:BaseByte + X] Command Token Table 10: MultiPackBufferFrag payload 302 The BaseByte field encodes the index of the first byte of the buffer being transmitted. The 303 BaseByte value is always less than or equal to 127, due to the limitation imposed on the 304 maximum buffer size (128 bytes). 305 306 This field is followed by as many bytes of the ANS buffer as possible, until one of the two 307 following conditions is met: 308 • All requested bytes of the ANS buffer, starting from byte BaseByte, can fit in the 309 payload. 310 • The maximum payload length is reached; at least one other fragment will have to be 311 sent to complete the transmission of the requested ANS buffer. 312 Note: The maximum payload length (MaxPayloadLen) depends on 313 the LoRaWAN data rate used for transmission. 314 315 The transmission of the fragmented ANS buffer is aborted whenever a valid multi-package 316 access command or command set (different from the MultiPackBufferReq command) is 317 received. 318 • If a MultiPackBufferReq command is received, the device SHALL abort the 319 previous fragmented transmission and start transmitting the newly requested ANS 320 buffer segment(s). 321 • If any other command is received, the device SHALL abort the previous fragmented 322 transmission, clear the ANS buffer, and start processing the new command set. 323 324 Example: Let's assume that following a multi-package command set with Token=3, the ANS buffer contains 20 bytes (noted ANS[0..19]). The maximum payload length that can be transported is 11 bytes. The end-device will transmit the following message sequence on FPort 225: First message (11 bytes): CommandID BaseByte Buffer bytes (8) Command Token 0x02 0 ANS[0..7] 0x03 Table 11: MultiPackBufferFrag command (first message) Second message (11 bytes): CommandID BaseByte Buffer bytes (8) Command Token 0x02 8 ANS[8..15] 0x03 Table 12: MultiPackBufferFrag command (second message)