TSCH: configurable byte air time and PHY overhead

arch/cpu/cc26xx-cc13xx/cc13xx-cc26xx-def.h

@@ -36,6 +36,10 @@
 /*---------------------------------------------------------------------------*/
 /* TSCH related defines */
 
+/* 1 len byte, 2 bytes CRC */
+#define RADIO_PHY_OVERHEAD         3
+/* 250kbps data rate. One byte = 32us */
+#define RADIO_BYTE_AIR_TIME       32
 /* Delay between GO signal and SFD */
 #define RADIO_DELAY_BEFORE_TX ((unsigned)US_TO_RTIMERTICKS(81))
 /* Delay between GO signal and start listening.

arch/cpu/simplelink-cc13xx-cc26xx/cc13xx-cc26xx-def.h

@@ -57,6 +57,10 @@
 /*---------------------------------------------------------------------------*/
 /* TSCH related defines */
 
+/* 1 len byte, 2 bytes CRC */
+#define RADIO_PHY_OVERHEAD         3
+/* 250kbps data rate. One byte = 32us */
+#define RADIO_BYTE_AIR_TIME       32
 /* Delay between GO signal and SFD */
 #define RADIO_DELAY_BEFORE_TX       ((unsigned)US_TO_RTIMERTICKS(81))
 /* Delay between GO signal and start listening.

arch/platform/cooja/contiki-conf.h

@@ -122,6 +122,10 @@ typedef unsigned long clock_time_t;
 /* Use 64-bit rtimer (default in Contiki-NG is 32) */
 #define RTIMER_CONF_CLOCK_SIZE 8
 
+/* 1 len byte, 2 bytes CRC */
+#define RADIO_PHY_OVERHEAD         3
+/* 250kbps data rate. One byte = 32us */
+#define RADIO_BYTE_AIR_TIME       32
 #define RADIO_DELAY_BEFORE_TX 0
 #define RADIO_DELAY_BEFORE_RX 0
 #define RADIO_DELAY_BEFORE_DETECT 0

arch/platform/jn516x/jn516x-def.h

@@ -38,6 +38,10 @@
 
 #undef putchar
 
+/* 1 len byte, 2 bytes CRC */
+#define RADIO_PHY_OVERHEAD         3
+/* 250kbps data rate. One byte = 32us */
+#define RADIO_BYTE_AIR_TIME       32
 /* Delay between GO signal and SFD
  * Measured 153us between GO and preamble. Add 5 bytes (preamble + SFD) air time: 153+5*32 = 313 */
 #define RADIO_DELAY_BEFORE_TX ((unsigned)US_TO_RTIMERTICKS(313))

arch/platform/sky/sky-def.h

@@ -43,6 +43,11 @@
  * Definitions below are dictated by the hardware and not really
  * changeable!
  */
+
+ /* 1 len byte, 2 bytes CRC */
+ #define RADIO_PHY_OVERHEAD         3
+ /* 250kbps data rate. One byte = 32us */
+ #define RADIO_BYTE_AIR_TIME       32
 /* Delay between GO signal and SFD: radio fixed delay + 4Bytes preample + 1B SFD -- 1Byte time is 32us
  * ~327us + 129preample = 456 us */
 #define RADIO_DELAY_BEFORE_TX ((unsigned)US_TO_RTIMERTICKS(456))

os/net/mac/tsch/tsch-const.h

@@ -80,7 +80,7 @@
 /* Calculate packet tx/rx duration in rtimer ticks based on sent
  * packet len in bytes with 802.15.4 250kbps data rate.
  * One byte = 32us. Add two bytes for CRC and one for len field */
-#define TSCH_PACKET_DURATION(len) US_TO_RTIMERTICKS(32 * ((len) + 3))
+#define TSCH_PACKET_DURATION(len) US_TO_RTIMERTICKS(RADIO_BYTE_AIR_TIME * ((len) + RADIO_PHY_OVERHEAD))
 
 /* Convert rtimer ticks to clock and vice versa */
 #define TSCH_CLOCK_TO_TICKS(c) (((c) * RTIMER_SECOND) / CLOCK_SECOND)