nimble/phy: Fix tx-tx transition timing

Delay for event END was always included in tx-tx transition
calculations which resulted in invalid calculations for tx-tx transition
anchored at packet start. This fixes the issue and also fixes timing for
event ADDRESS since it seems to be different that the one for END event.

nimble/drivers/nrf5x/src/ble_phy.c

@@ -227,6 +227,13 @@ static const uint8_t g_ble_phy_t_txdelay[BLE_PHY_NUM_MODE] = {
  [BLE_PHY_MODE_CODED_125KBPS] = 5,
  [BLE_PHY_MODE_CODED_500KBPS] = 5
 };
+/* delay between EVENTS_ADDRESS and txd access address */
+static const uint8_t g_ble_phy_t_txaddrdelay[BLE_PHY_NUM_MODE] = {
+ [BLE_PHY_MODE_1M] = 7,
+ [BLE_PHY_MODE_2M] = 5,
+ [BLE_PHY_MODE_CODED_125KBPS] = 17,
+ [BLE_PHY_MODE_CODED_500KBPS] = 17
+};
 /* delay between EVENTS_END and end of txd packet */
 static const uint8_t g_ble_phy_t_txenddelay[BLE_PHY_NUM_MODE] = {
  [BLE_PHY_MODE_1M] = 6,
@@ -1104,25 +1111,24 @@ ble_phy_tx_end_isr(void)
  */
  } else if (transition == BLE_PHY_TRANSITION_TX_TX) {
  if (g_ble_phy_data.txtx_time_anchor) {
- /* Schedule next TX relative to current TX end. TX end timestamp is
- * captured in CC[2].
- */
- tx_time = NRF_TIMER0->CC[2] + g_ble_phy_data.txtx_time_us;
- } else {
- /* Schedule next TX relative to current TX start. AA timestamp is
- * captured in CC[1], we need to adjust for sync word to get TX
- * start.
- */
- tx_time = NRF_TIMER0->CC[1] - ble_ll_pdu_syncword_us(tx_phy_mode) +
- g_ble_phy_data.txtx_time_us;
- /* Adjust for delay between EVENT_ADDRESS and actual address TX time */
- /* FIXME assume this is the same as EVENT_END to end, but we should
- * measure this to be sure */
+ /* Calculate TX anchor relative to current TX end */
+
+ /* TX end timestamp is captured in CC[2] */
+ tx_time = NRF_TIMER0->CC[2];
+ /* Adjust for delay between EVENT_END and actual TX end time */
  tx_time += g_ble_phy_t_txenddelay[tx_phy_mode];
+ } else {
+ /* Calculate TX anchor relative to current TX start */
+
+ /* AA timestamp is captured in CC[1] */
+ tx_time = NRF_TIMER0->CC[1];
+ /* Adjust for delay between EVENT_ADDRESS and actual AA time ota */
+ tx_time += g_ble_phy_t_txaddrdelay[tx_phy_mode];
+ /* Adjust by sync word length to get TX start time */
+ tx_time -= ble_ll_pdu_syncword_us(tx_phy_mode);
  }
 
- /* Adjust for delay between EVENT_END and actual TX end time */
- tx_time += g_ble_phy_t_txenddelay[tx_phy_mode];
+ tx_time += g_ble_phy_data.txtx_time_us;
 
 #if PHY_USE_FEM_PA
  fem_time = tx_time - MYNEWT_VAL(BLE_FEM_PA_TURN_ON_US);