Hausbus/Paketformat
Formatbeschreibung
| Byte | Name | Bedeutung |
|---|---|---|
| 00 | destination | Zieladresse |
| 01 | source | Senderadresse |
| 02 | header_chk | Prüfsumme des Headers |
| 03 | payload_chk | Prüfsumme des Payloads |
| 04 | length_hi | Most Significant Bits der Payloadlänge |
| 05 | length_lo | Least Significant Bits der Payloadlänge |
| 06 | Payload | |
| … | … |
Beispiel
uint8_t buffer[32];
struct buspkt *packet = (struct buspkt*)buffer;
uint8_t *payload = buffer;
payload += sizeof(struct buspkt);
packet->destination = 0x01; /* pinpad-controller */
packet->source = 0x00; /* busmaster */
packet->length_hi = 0x00;
packet->length_lo = 10;
packet->payload_chk = 0xFF; /* not yet implemented */
packet->header_chk = packet->destination + packet->source + packet->payload_chk + packet->length_hi + packet->length_lo;
strncpy(payload, "get_status", strlen("get_status"));
…ergibt:
{
0x01, 0x00, 0x0a, 0xff, 0x00, 0x0a,
0x67, 0x65, 0x74, 0x5f, 0x73, 0x74, 0x61, 0x74, 0x75, 0x73
}
Vorsicht: Pakete befüllen sollte keiner selber müssen. Das nimmt einem die lib/bus.c ab mit fmt_packet().