From 62d558a6db9cf823c7926fc74ed5610a0dcbad23 Mon Sep 17 00:00:00 2001 From: rincon Date: Fri, 5 Sep 2008 20:39:00 +0000 Subject: [PATCH] added more descriptive comments about the header --- tos/chips/cc2420/CC2420.h | 39 +++++++++++++++++++++++++++++++++++++-- 1 file changed, 37 insertions(+), 2 deletions(-) diff --git a/tos/chips/cc2420/CC2420.h b/tos/chips/cc2420/CC2420.h index 1d607b92..798107f0 100644 --- a/tos/chips/cc2420/CC2420.h +++ b/tos/chips/cc2420/CC2420.h @@ -43,8 +43,43 @@ typedef uint8_t cc2420_status_t; #endif /** - * CC2420 header. An I-frame (interoperability frame) header has an - * extra network byte specified by 6LowPAN + * CC2420 header definition. + * + * An I-frame (interoperability frame) header has an extra network + * byte specified by 6LowPAN + * + * Length = length of the header + payload of the packet, minus the size + * of the length byte itself (1). This is what allows for variable + * length packets. + * + * FCF = Frame Control Field, defined in the 802.15.4 specs and the + * CC2420 datasheet. + * + * DSN = Data Sequence Number, a number incremented for each packet sent + * by a particular node. This is used in acknowledging that packet, + * and also filtering out duplicate packets. + * + * DestPan = The destination PAN (personal area network) ID, so your + * network can sit side by side with another TinyOS network and not + * interfere. + * + * Dest = The destination address of this packet. 0xFFFF is the broadcast + * address. + * + * Src = The local node ID that generated the message. + * + * Network = The TinyOS network ID, for interoperability with other types + * of 802.15.4 networks. + * + * Type = TinyOS AM type. When you create a new AMSenderC(AM_MYMSG), + * the AM_MYMSG definition is the type of packet. + * + * TOSH_DATA_LENGTH defaults to 28, it represents the maximum size of + * the payload portion of the packet, and is specified in the + * tos/types/message.h file. + * + * All of these fields will be filled in automatically by the radio stack + * when you attempt to send a message. */ typedef nx_struct cc2420_header_t { nxle_uint8_t length; -- 2.39.2