Ethernet Driver (Eth) Setup - MCAL & Driver Development

Ethernet MCAL Architecture

Ethernet BSW Stack

  SoAd (Socket Adaptor) -- UDP/TCP socket interface
  DoIP -- Diagnostics over IP
  SOME/IP -- Service-Oriented Middleware
        |
  TcpIp -- TCP/IP stack
        |
  EthIf (Ethernet Interface) -- controller multiplexing, VLAN
        |
  Eth (MCAL) -- MAC Tx/Rx, descriptor ring, flow control
  EthTrcv (MCAL) -- PHY mode (100BASE-T1, 1000BASE-T1, 100BASE-TX)
        |
  Hardware: Ethernet MAC (on-chip) + PHY IC (TJA1101, BCM89811...)

  Eth MCAL responsibilities:
  - Descriptor ring management (Tx/Rx ring buffers)
  - Frame transmission: Eth_Transmit() loads Tx descriptor
  - Frame reception: ISR fires on Rx; Eth calls EthIf_RxIndication()
  - MAC address configuration
  - Flow control (IEEE 802.3 PAUSE frames)
  - Statistics: Eth_GetCounterValues() for MIB counters

ETH Controller and Buffer Configuration

Ceth_cfg.c

/* Ethernet MCAL configuration for TC387 with TJA1101 100BASE-T1 PHY */
#include "Eth.h"

#define ETH_CTRL_IDX        0u
#define ETH_RX_RING_SIZE    8u    /* 8 Rx descriptors */
#define ETH_TX_RING_SIZE    8u    /* 8 Tx descriptors */
#define ETH_FRAME_SIZE      1522u /* max Ethernet frame (with VLAN) */

/* Rx buffer pool: ring_size * max_frame_size bytes */
static uint8 Eth_RxBufferPool[ETH_RX_RING_SIZE][ETH_FRAME_SIZE];
static uint8 Eth_TxBufferPool[ETH_TX_RING_SIZE][ETH_FRAME_SIZE];

const Eth_ControllerConfigType EthCtrlConfig[] = {
    {
        .EthCtrlIdx          = ETH_CTRL_IDX,
        .EthMacAddress       = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55},
        .EthCtrlMtu          = 1500u,
        .EthRxBufTotal       = ETH_RX_RING_SIZE,
        .EthTxBufTotal       = ETH_TX_RING_SIZE,
        .EthRxBufLenByte     = ETH_FRAME_SIZE,
        .EthTxBufLenByte     = ETH_FRAME_SIZE,
        .EthRxBufPtr         = &Eth_RxBufferPool[0][0],
        .EthTxBufPtr         = &Eth_TxBufferPool[0][0],
        .EthPhyMdioClkDiv    = 25u,   /* MDIO clock = SPB/25 = 4 MHz */
    },
};

/* EthTrcv: set PHY to 100BASE-T1 normal mode */
void Eth_InitPhy(void)
{
    Eth_Init(&EthConfig);
    EthTrcv_SetTransceiverMode(0u, ETHTRCV_MODE_ACTIVE);
    Eth_SetControllerMode(ETH_CTRL_IDX, ETH_MODE_ACTIVE);
}

Summary

Automotive Ethernet MCAL (Eth + EthTrcv) is considerably more complex than CAN MCAL because Ethernet requires descriptor ring buffer management, PHY initialisation via MDIO, and integration with a full TCP/IP stack. The descriptor ring size directly impacts latency and throughput: too few Rx descriptors and frames are dropped when bursts arrive; too many wastes RAM. The typical ECU configuration (8 Rx + 8 Tx descriptors) suits SOME/IP and DoIP workloads. For AUTOSAR Adaptive (AP) on high-performance ECUs, the ring sizes may be 64 or more. EthTrcv initialisation (PHY auto-negotiation or forced 100BASE-T1) must complete before Eth_SetControllerMode(ACTIVE) to avoid transmitting on a link that is not yet up.

🔬 Deep Dive — Core Concepts Expanded

This section builds on the foundational concepts covered above with additional technical depth, edge cases, and configuration nuances that separate competent engineers from experts. When working on production ECU projects, the details covered here are the ones most commonly responsible for integration delays and late-phase defects.

Key principles to reinforce:

Configuration over coding: In AUTOSAR and automotive middleware environments, correctness is largely determined by ARXML configuration, not application code. A correctly implemented algorithm can produce wrong results due to a single misconfigured parameter.
Traceability as a first-class concern: Every configuration decision should be traceable to a requirement, safety goal, or architecture decision. Undocumented configuration choices are a common source of regression defects when ECUs are updated.
Cross-module dependencies: In tightly integrated automotive software stacks, changing one module's configuration often requires corresponding updates in dependent modules. Always perform a dependency impact analysis before submitting configuration changes.

🏭 How This Topic Appears in Production Projects

Project integration phase: The concepts covered in this lesson are most commonly encountered during ECU integration testing — when multiple software components from different teams are combined for the first time. Issues that were invisible in unit tests frequently surface at this stage.
Supplier/OEM interface: This is a topic that frequently appears in technical discussions between Tier-1 ECU suppliers and OEM system integrators. Engineers who can speak fluently about these details earn credibility and are often brought into critical design review meetings.
Automotive tool ecosystem: Vector CANoe/CANalyzer, dSPACE tools, and ETAS INCA are the standard tools used to validate and measure the correct behaviour of the systems described in this lesson. Familiarity with these tools alongside the conceptual knowledge dramatically accelerates debugging in real projects.

⚠️ Common Mistakes and How to Avoid Them

Assuming default configuration is correct: Automotive software tools ship with default configurations that are designed to compile and link, not to meet project-specific requirements. Every configuration parameter needs to be consciously set. 'It compiled' is not the same as 'it is correctly configured'.
Skipping documentation of configuration rationale: In a 3-year ECU project with team turnover, undocumented configuration choices become tribal knowledge that disappears when engineers leave. Document why a parameter is set to a specific value, not just what it is set to.
Testing only the happy path: Automotive ECUs must behave correctly under fault conditions, voltage variations, and communication errors. Always test the error handling paths as rigorously as the nominal operation. Many production escapes originate in untested error branches.
Version mismatches between teams: In a multi-team project, the BSW team, SWC team, and system integration team may use different versions of the same ARXML file. Version management of all ARXML files in a shared repository is mandatory, not optional.

📊 Industry Note

Engineers who master both the theoretical concepts and the practical toolchain skills covered in this course are among the most sought-after professionals in the automotive software industry. The combination of AUTOSAR standards knowledge, safety engineering understanding, and hands-on configuration experience commands premium salaries at OEMs and Tier-1 suppliers globally.