29. MCAN

29.1. Overview

This sample demonstrates a comprehensive set of MCAN (Bosch M_CAN) peripheral features on HPMicro SoCs. All demos share a common infrastructure (mcan_app_common.c/.h) and are presented through an interactive serial menu. Each menu option is self-contained: it initialises the CAN peripheral, runs the test, prints the result, and returns to the menu.

29.2. Source Organisation

The sample is split into one file per feature area so that each demo can be read independently.

Source file	Description
mcan_app_common.c/.h	Shared infrastructure: main(), interactive menu, unified ISR dispatcher (board_can_isr), CAN instance table (s_can_info[]), AHB-RAM message-buffer helpers (mcan_setup_msg_buf), and common utility functions (show_received_can_message, get_timestamp_hex_string, handle_can_error).
mcan_loopback_demo.c	Internal-loopback tests: polling loopback for every SoC CAN instance (CAN 2.0 and CAN-FD), and interrupt-driven loopback for the board CAN.
mcan_echo_demo.c	Two-board echo test. One board acts as initiator (sends a frame), the other as responder (echoes the payload back with a different ID).
mcan_txrx_demo.c	Bulk transmission: 2048 classic CAN 2.0 frames, then 2048 CAN-FD frames with manually specified bit-timing and optional Transmitter Delay Compensation (TDC).
mcan_filter_demo.c	Six filter test cases covering all MCAN filter types: classic filter (STD and EXT ID), range filter, and dual-ID (specified-ID) filter. Each case transmits 2048 frames and counts accepted frames.
mcan_error_demo.c	Error handling: triggers a no-ACK condition (board disconnected from bus) for both CAN 2.0B and CAN-FD, then decodes and prints the PSR / ECR registers via handle_can_error().
mcan_rxbuf_demo.c	Dedicated RX buffer (RXBUF) demo. A classic filter routes only frames with ID 0x123 into RXBUF index 1; all other IDs are rejected. TX is done via a dedicated TX buffer in non-blocking mode.
mcan_tx_event_demo.c	TX Event FIFO demo. Each transmitted frame carries an 8-bit message marker; after transmission the hardware stores a TX-event element that echoes the marker back, allowing the application to correlate every sent frame with its transmission result.
mcan_timestamp_demo.c	Three timestamp capture modes: 32-bit TSU (Timestamp Unit), 64-bit TSU (extended precision), and the MCAN internal 16-bit counter. For each mode both the TX-event timestamp and the RX-message timestamp are printed for comparison.
mcan_timeout_demo.c	Timeout counter feature: four trigger modes are exercised in sequence — continuous (free-running), TX-Event-FIFO-triggered, RX-FIFO0-triggered, and RX-FIFO1-triggered. Each case is fully self-contained.
mcan_txcancel_demo.c	TX cancellation: demonstrates selective cancellation of pending TX FIFO entries and dedicated TX buffer entries. Slot 0 is left to complete normally; slots 1-3 are cancelled and the cancellation-finished flags are verified.
mcan_txqueue_demo.c	TX Queue mode (interrupt-driven, fully asynchronous). The CPU fills the hardware queue as fast as possible with 2048 frames (IDs 0x000-0x7FF); when the queue is momentarily full the submission busy-spins until the hardware frees a slot. Received loopback echoes are accumulated by the ISR concurrently. The hardware schedules transmission by CAN priority (lowest ID first), unlike TX FIFO which preserves submission order.

29.3. Board Setting

No special hardware settings are required for self-contained tests (options 0, 1, 6-d). Exceptions:

• Options 2 / 3 (Echo test): connect two boards to the same CAN bus.

• Options 4 / 5 (Bulk TX): connect the board to a CAN bus or CAN analyser so the transmitted frames can be observed.

• Option 6 (Error test): remove the board from the CAN bus (disconnect the CAN transceiver) so the no-ACK condition can be triggered.

29.4. Running the example

When the example runs successfully, the following menu is printed on the serial terminal:

*******************************************************************************
*                                                                             *
*                         CAN Example Menu                                    *
*                                                                             *
* 0 - Run loopback test for all supported CAN controllers (CAN and CANFD)     *
* 1 - Run loopback test for board supported CAN controller (interrupt mode)   *
* 2 - Echo test between two board:initiator                                   *
* 3 - Echo test between two board:responder                                   *
* 4 - Send multiple classic CAN messages for transmission check               *
* 5 - Send multiple CANFD messages for transmission check                     *
* 6 - CAN error test (Need to remove current node from CAN BUS for this test) *
* 7 - CAN filter test                                                         *
* 8 - CAN RXBUF test                                                          *
* 9 - CAN TX EVENT FIFO test                                                  *
* a - CAN Timestamp Test                                                      *
* b - CAN timeout counter Test                                                *
* c - CAN TXBUF cancellation Test                                             *
* d - CAN TX Queue test                                                       *
*                                                                             *
*******************************************************************************

29.4.1. Menu option details

Key	Name	What it does / what to expect
0	Loopback (all CAN)	Iterates every MCAN instance on the SoC. For each instance runs one CAN 2.0 loopback pass and one CAN-FD loopback pass in polling mode. Prints PASSED / FAILED per instance. No external connection needed.
1	Loopback (interrupt)	Runs 2048 loopback frames on BOARD_APP_CAN_BASE using interrupts. Prints the received ID for every frame. No external connection needed.
2	Echo initiator	Initialises CAN at 500 kbps in normal mode, sends one frame (STD ID 0x123, DLC=8), and waits for the echo reply from the responder board. Prints the echoed payload.
3	Echo responder	Initialises CAN at 500 kbps in normal mode, waits for a frame from the initiator, prints it, then echoes the payload back with STD ID 0x321.
4	Bulk TX classic	Transmits 2048 CAN 2.0 frames (IDs 0x000-0x7FF) at 1 Mbps in normal mode. Board must be connected to a CAN bus or analyser.
5	Bulk TX CAN-FD	Transmits 2048 CAN-FD frames (DLC=15, 64 bytes) with manually configured bit-timing (1 Mbps arbitration / 2 Mbps data). Board must be connected to a CAN bus or analyser.
6	Error test	Attempts transmission with no other node on the bus to trigger a no-ACK error. Runs both CAN 2.0B (500 kbps, DLC=8) and CAN-FD (500 kbps / 2 Mbps, DLC=15) cases, then prints the PSR and ECR register state. Board must be disconnected from the CAN bus.
7	Filter test	Runs six sub-cases in sequence, each reconfiguring the peripheral with a different filter type and transmitting 2048 frames to verify the expected accept count: Case 0: Classic filter, STD ID, mask bit[2:0] → expect 256 accepted Case 1: Classic filter, exact STD ID (16 IDs) → expect 16 accepted Case 2: Range filter, STD ID 0x000-0x00F → expect 16 accepted Case 3: Dual-ID filter, STD ID 0x22 & 0x33 → expect 2 accepted Case 4: Dual-ID filter, same IDs, repeat run → expect 2 accepted Case 5: Classic filter, EXT ID, mask bit[2:0] → expect 256 accepted
8	RXBUF test	Configures a classic filter to route STD ID 0x123 into dedicated RX buffer index 1. Transmits 2048 frames; only the frame with ID 0x123 should be stored. Prints the received ID and PASSED / FAILED.
9	TX Event FIFO	Transmits 256 frames via TX FIFO with event_fifo_control=1 and an 8-bit message marker. After each transmission the TX-event element is read back and the marker is printed to confirm round-trip correlation.
a	Timestamp	Runs three timestamp modes (32-bit TSU, 64-bit TSU, internal 16-bit counter). For each mode sends one loopback frame and prints both the TX-event timestamp and the RX-message timestamp for comparison.
b	Timeout counter	Runs four timeout trigger modes in sequence: continuous, TX-Event-FIFO triggered, RX-FIFO0 triggered, RX-FIFO1 triggered. Prints PASSED / FAILED for each mode.
c	TX cancellation	Submits four frames to TX FIFO slots 0-3 and immediately cancels slots 1-3. Then repeats using dedicated TX buffers 0-3. Prints PASSED if all three cancellations completed for each scenario.
d	TX Queue	Enables TX Queue mode (hardware priority-ordered scheduling). Fills the queue with 2048 frames (IDs 0x000-0x7FF) as fast as possible; loopback echoes are received asynchronously by the ISR. Verifies that all 2048 IDs were echoed back and prints PASSED / FAILED.