/*
* \brief Starts slotted CSMA
*/
bool slotted_csma_start(bool perform_frame_retry)
{
PIN_CSMA_START(); /* debug pin to switch on: define ENABLE_DEBUG_PINS,
* pal_config.h */
bool return_val = false; /* Assume error case */
if (check_beacon_reception()) {
tal_state = TAL_SLOTTED_CSMA;
csma_param_init();
if (perform_frame_retry) {
number_of_tx_retries = 0;
} else {
/* Use the max value to indicate that no retries are
* required. */
number_of_tx_retries = tal_pib.MaxFrameRetries;
}
calculate_transaction_duration();
/* Get a random backoff period duration. */
remaining_backoff_periods = (uint8_t)(rand() & ((1 << BE) - 1));
csma_backoff_calculation();
return_val = true;
}
return return_val;
}
/**
* @brief Starts slotted CSMA
*/
void slotted_csma_start(bool perform_frame_retry)
{
PIN_CSMA_START(); // debug pin to switch on: define ENABLE_DEBUG_PINS, pal_config.h
tal_state = TAL_SLOTTED_CSMA;
if (check_beacon_reception() == false)
{
tal_csma_state = NO_BEACON_TRACKING;
return;
}
csma_param_init();
if (perform_frame_retry)
{
number_of_tx_retries = 0;
}
else
{
// use the max value to indicate that no retries are required
number_of_tx_retries = tal_pib_MaxFrameRetries;
}
calculate_transaction_duration();
/* Get a random backoff period duration. */
remaining_backoff_periods = (uint8_t)(rand() & ((1 << BE) - 1));
csma_backoff_calculation();
}
/**
* \brief State machine handling slotted CSMA
*/
void slotted_csma_state_handling(void)
{
switch (tal_csma_state) {
case BACKOFF_WAITING_FOR_CCA_TIMER:
break;
case BACKOFF_WAITING_FOR_BEACON:
/*
* Do not perform any operation and wait until the next beacon
* reception. If several beacons are not received, the beacon
* loss
* timer expires and stops the entire transaction.
*/
break;
case CSMA_HANDLE_BEACON:
/* debug pin to switch on: define ENABLE_DEBUG_PINS,
* pal_config.h */
PIN_WAITING_FOR_BEACON_END();
PIN_BEACON_LOSS_TIMER_END();
pal_timer_stop(TAL_CSMA_BEACON_LOSS_TIMER);
csma_backoff_calculation();
break;
case CSMA_ACCESS_FAILURE:
NB++;
BE++;
/* ensure that BE is no more than macMaxBE */
if (BE > tal_pib.MaxBE) { /* macMaxBE */
BE = tal_pib.MaxBE; /* macMaxBE */
}
if (NB > macMaxCSMABackoffs) {
/* terminate with channel access failure */
tx_done(MAC_CHANNEL_ACCESS_FAILURE);
} else {
/* restart backoff */
csma_backoff_calculation();
}
break;
case NO_BEACON_TRACKING:
/* terminate with channel access failure */
tx_done(MAC_CHANNEL_ACCESS_FAILURE);
break;
case FRAME_SENDING:
/* waiting for end of frame transmission */
break;
case TX_DONE_SUCCESS:
tx_done(MAC_SUCCESS);
break;
case TX_DONE_FRAME_PENDING:
tx_done(TAL_FRAME_PENDING);
break;
case TX_DONE_NO_ACK:
if (number_of_tx_retries < tal_pib.MaxFrameRetries) {
number_of_tx_retries++;
set_trx_state(CMD_RX_AACK_ON);
/*
* Start the entire CSMA procedure again,
* but do not reset the number of transmission attempts.
*/
BE++;
/* ensure that BE is no more than macMaxBE */
if (BE > tal_pib.MaxBE) { /* macMaxBE */
BE = tal_pib.MaxBE; /* macMaxBE */
}
NB = 0;
remaining_backoff_periods
= (uint8_t)(rand() & ((1 << BE) - 1));
csma_backoff_calculation();
} else {
tx_done(MAC_NO_ACK);
}
PIN_NO_ACK_END();
break;
default:
Assert("INVALID CSMA status" == 0);
break;
}
} /* csma_ca_state_handling() */
