Hi Ahed, > buf[1] = IEEE802154_FCF_VERS_V1 means the 12th bit is set to 1, or the 11th > bit if we start counting FCF bits from 0 to 15.
Not quite, it sets 12th bit counting from 0 (or 13th counting from 1, but let's not count from 1 :) ). See https://pastebin.com/D29acwf4 Hope this helps. Best, Anton On Wed, Nov 27, 2019 at 3:09 PM Aboodi Ahed Hussein Ali <abo...@student.usm.my> wrote: > > Thank you, Anton. Please bear with me if I misunderstood any programming > fundamentals, > > I agree that the 4th bit of buf[1] is set to 1, but according to FCF format > the 13th and 14th bits, of buf[0-1], must be set for frame version, or if you > start counting the FCF bits from 0 to 15, bit 12 and bit 13 are the frame > version bits. > > buf[1] = IEEE802154_FCF_VERS_V1 means the 12th bit is set to 1, or the 11th > bit if we start counting FCF bits from 0 to 15. > > Besides, when I did print buf[1] I get decimal 16, while I should get decimal > 8 for the frame version to be set. > > Ahed > . > ________________________________ > From: Aboodi Ahed Hussein Ali <abo...@student.usm.my> > Sent: Wednesday, November 27, 2019 9:15 PM > To: RIOT OS developers list <devel@riot-os.org> > Subject: Re: IEEEE 802.15.4 FCF Format in > "RIOT/sys/net/link_layer/ieee802154/ieee802154.c" > > Thank you, Joakim, but I don't think it is correct. > > Starting from 0, bit No. 3 of the IEEE802154_FCF_VERS_V1 (Hex 0x10 or binary: > 0001 0000) have the value 1, thus 0 to 3 represent 8 to 11 on buf[1]. > therefor, the bit No. 3, in 0x10, is set on bit No. 11 of the FCF. > > Not sure if the below illustration will be on a layout. > ---buf[0] buf[1] > 0000 0000 0000 0000 <-- FCF > ------------- 0001 0000 <-- IEEE802154_FCF_VERS_V1 > > This means that the Frame version is not really set probably or this file > "RIOT/sys/net/link_layer/ieee802154/ieee802154.c" follows a different FCF > format!! > > Am I correct or did I misunderstand that? > > Ahed > ________________________________ > From: Aboodi Ahed Hussein Ali > Sent: Wednesday, November 27, 2019 5:58 AM > To: RIOT OS developers list <devel@riot-os.org> > Subject: IEEEE 802.15.4 FCF Format in > "RIOT/sys/net/link_layer/ieee802154/ieee802154.c" > > Hi all, > > I am having a hard time understanding how the "ieee802154_set_frame_hdr" > function, found in this link, sets the Frame Control Field (FCF) for 802.15.4 > frame header. > Following the IEEE 802.15.4 FCF format, frame version should be at the > 12-13th bit of the 2-byte FCF, while in the function code, the frame version > was set at the 11th bit. Does it uses different FCF format or am I missing > something? > > This is the first part of the function: > > size_t ieee802154_set_frame_hdr(uint8_t *buf, const uint8_t *src, size_t > src_len, > const uint8_t *dst, size_t dst_len, > le_uint16_t src_pan, le_uint16_t dst_pan, > uint8_t flags, uint8_t seq) > { > int pos = 3; /* 0-1: FCS, 2: seq */ > uint8_t type = (flags & IEEE802154_FCF_TYPE_MASK); > > buf[0] = flags; > buf[1] = IEEE802154_FCF_VERS_V1; // IEEE802154_FCF_VERS_V1 is > defined as 0x10 > > if (((src_len != 0) && (src == NULL)) || > ((dst_len != 0) && (dst == NULL))) { > return 0; > } > ... > ... > > The first two bytes of the *buf represent the FCF. I would appreciate it if > someone explains or provides the FCF format that RIOT-OS uses. > > Thank you, > Ahed > > _______________________________________________ > devel mailing list > devel@riot-os.org > https://lists.riot-os.org/mailman/listinfo/devel _______________________________________________ devel mailing list devel@riot-os.org https://lists.riot-os.org/mailman/listinfo/devel
