Hello. On Wed, 2010-05-05 at 23:08, Xue Liu wrote: > 2010/5/4 Stefan Schmidt <ste...@datenfreihafen.org> > > > This is an addition to the last fix for adding the length byte. With > > hardware > > FCS enabled we are obliged to set the length including the 2 bytes for the > > FCS. Our skb does only have the len for the data it contains so we need to > > adjust it for the length byte. > > I still don`t know why I must add 2 bytes for the FCS. I read cc2420 > datasheet again. > In Page 38, it said: > "In transmit mode the FCS is appended at the correct position defined by the > length > filed. The FCS is not written to the TXFIFO, but stored in a separate > 16-bit register."
That is all right. The hardware does calculate the FCS and adds it after we pushed the data in the FIFO. Still the length byte is another issue. Please see page 37 16.2: "Note that the length field does not include the length field itself. It does however include the FCS (Frame Check Sequence), even if this is inserted automatically by CC2420 hardware" > I think FCS should automatically add to MPDU by cc2420. It is. But as the hardware does not calculate the length field it must be set in the driver and taken care about the added FCS in hardware. regards Stefan Schmidt ------------------------------------------------------------------------------ _______________________________________________ Linux-zigbee-devel mailing list Linux-zigbee-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-zigbee-devel
