FlexRay Communication Cycle Design

# FlexRay communication cycle design: slot matrix generation
# Input: signal list with rates and payloads

import math

GDCYCLE_MS = 2     # 2 ms communication cycle
MAX_SLOTS  = 100   # available static slots
PAYLOAD_BYTES = 24 # gPayloadLengthStatic = 12 words = 24 bytes

signals = [
    # (name, payload_bytes, rate_ms, node)
    ("SteeringTorque",   8,  2, "ECU_EPS"),
    ("BrakePressure",   16,  2, "ECU_ESC"),
    ("WheelSpeeds",     16,  2, "ECU_ESC"),
    ("EngineStatus",    12,  2, "ECU_ENG"),   # 2ms → every cycle
    ("TransmissionCmd",  8,  4, "ECU_TCU"),   # 4ms → every 2nd cycle
    ("XCP_Data",        24, 10, "ECU_ENG"),   # 10ms → every 5th cycle
]

slot_matrix = []
for name, payload, rate_ms, node in signals:
    cycles_per_tx = max(1, rate_ms // GDCYCLE_MS)
    slots_needed  = math.ceil(payload / PAYLOAD_BYTES)
    slot_matrix.append({
        "signal": name, "node": node,
        "slots": slots_needed, "cycle_rep": cycles_per_tx
    })
    print(f"{name}: {slots_needed} slot(s) every {cycles_per_tx} cycle(s) — {node}")

total_static = sum(s["slots"] for s in slot_matrix)
print(f"\nTotal static slots: {total_static}/{MAX_SLOTS} "
      f"({total_static/MAX_SLOTS*100:.0f}% utilised)")

  FlexRay_Cluster_0
  12  



  Safety_Frame_Slot1
  24  
  
    /Com/IPdus/SteeringTorque_PDU
    MOST-SIGNIFICANT-BYTE-FIRST
    0  
  
  
    /Com/IPdus/BrakeRequest_PDU
    8  
  
  

/* FlexRay startup sequence per AUTOSAR FrNm and EcuM */
#include "Fr.h"
#include "FrNm.h"

void FlexRay_StartupSequence(void)
{
    Fr_POCStatusType poc_status;

    /* Step 1: Wakeup — send WUS symbol on Channel A */
    Fr_SendWUP(FR_CHANNEL_A);
    /* WUS is ~50 µs duration pulse; all sleeping nodes detect it */

    /* Step 2: Wait for wakeup observation period (50 ms default) */
    /* During this time, other nodes wake up and enter CONFIG state */

    /* Step 3: Enter READY state */
    Fr_AllowColdstart(FR_CHANNEL_A);

    /* Step 4: Cold-start (if this node is the first cold-start node) */
    /* Node transmits CAS (Collision Avoidance Symbol) then begins counting slots */
    Fr_StartCommunication(FR_CHANNEL_A);

    /* Step 5: Integration — other nodes synchronise to the running cluster */
    /* Integration complete when ≥ 2 nodes are synchronised */
    /* Monitor: Fr_GetPOCStatus() returns FR_POCSTATE_NORMAL_ACTIVE */
    do {
        Fr_GetPOCStatus(FR_CHANNEL_A, &poc_status);
    } while (poc_status.State != FR_POCSTATE_NORMAL_ACTIVE);

    /* FlexRay cluster operational */
    FrNm_StartupIndication();  /* Notify FrNm → triggers ComM network mode */
}