mbed-os/targets/TARGET_NUVOTON/TARGET_M460

Nuvoton M460 series

CAN

Current CAN HAL implementation has the following characteristics:

1. By default, filter handle 0 is configured to accept all messages as requested.
2. Support only single filter handle semantics, that is, filter handle 0. The handle argument passed to can_filter() or can_read() is ignored. All filter related operations are done on filter handle 0.

HyperRAM

HyperRAM, via Hyper Bus Interface Controller (HBI), is mapped to two regions: 0x0A00_0000–0x0BFF_FFFF and 0x8000_0000–0x81FF_FFFF, through which CPU can direct access.

Enable HBI for HyperRAM

To enable HBI for HyperRAM, create one Mbed OS application configuration file named mbed_app.json under root directory of your sample program. The file should have the following content which will enable HBI and configure its multi-function pins:

mbed_app.json:

{
    ......
    "target_overrides": {
        ......
        "NUMAKER_IOT_M467": {
            "target.hbi-enable": true,
            "target.hbi-mfp-reg-list": "0x40000534, 0x4000057C, 0x40000590, 0x40000594",
            "target.hbi-mfp-reg-msk-list": "0xFFFFFF00, 0xFFFFFFFF, 0xFFFF0000, 0xFFFFFFFF",
            "target.hbi-mfp-reg-val-list": "0x10101000, 0x10101010, 0x10100000, 0x10101010"
        }
    }
}

Where:

• hbi-mfp-reg-list: Comma-separated list of relevant multi-function pin registers
• hbi-mfp-reg-msk-list: Comma-separated list of relevant multi-function pin register masks
• hbi-mfp-reg-val-list: Comma-separated list of relevant multi-function pin register values

NOTE: Make sure your HyperRAM hardware is ready.

NOTE: Change the multi-function pins to align with your hardware.

Locate data at HyperRAM

In the port, the region 0x8000_0000–0x81FF_FFFF is chosen for the goal because on Mbed OS, MPU is enabled and the region is configured to be write-able, which naturally fits HyperRAM. To get to the goal, data must place in specified sections:

Locate initialized data

Initialized data are just like RW sections for ARM, .data sectionis for GCC_ARM, and readwrite sections for IAR. To locate them at HyperRAM, place in specified sections named .data.nu.hyperram.

__attribute__((section(".data.nu.hyperram")))
uint32_t my_data = 100;

Locate zero-initialized data

Zero-initialized data are just like ZI sections for ARM, .bss sections for GCC_ARM, and zeroinit sections for IAR. To locate them at HyperRAM, place in specified sections named.bss.nu.hyperram.

__attribute__((section(".bss.nu.hyperram")))
uint32_t my_bss;

NOTE: Don't mis-place in sections, or behavior is undefined because C runtime is not correctly initialized for these sections.

NOTE: Check linker-generated .map file to make sure your data are actually located at HyperRAM.