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ARM V2M Musca

Overview

The v2m_musca board configuration is used by Zephyr applications that run on the V2M Musca board. It provides support for the Musca ARM Cortex-M33 CPU and the following devices:

  • Nested Vectored Interrupt Controller (NVIC)

  • System Tick System Clock (SYSTICK)

  • Cortex-M System Design Kit GPIO

  • Cortex-M System Design Kit UART

ARM V2M Musca

More information about the board can be found at the V2M Musca Website.

Hardware

ARM V2M MUSCA provides the following hardware components:

  • ARM Cortex-M33

  • ARM IoT Subsystem for Cortex-M33

  • Memory

    • 128KB SRAM

    • 2MB of external SRAM

    • 8MB of external QSPI flash.

  • Debug

    • JTAG, SWD & 4 bit TRACE

    • DAPLink with a virtual UART port

  • Arduino interface

    • 16 3V3 GPIO.

    • UART.

    • SPI.

    • I2C.

    • I2S.

    • 3-channel PWM.

    • 6-channel analog interface.

  • On-board Peripherals

    • User RGB LED

    • Gyro sensor

    • Combined ADC/DAC/temperature sensor

User push buttons

The v2m_musca board provides the following user push buttons:

  • PBON power on/off.

  • nSRST: Cortex-M33 system reset and CoreSight debug reset.

  • ISP: Updates DAPLink firmware.

  • HWRST: Resets DAPLink.

Supported Features

The v2m_musca board configuration supports the following hardware features:

Interface

Controller

Driver/Component

NVIC

on-chip

nested vector interrupt controller

SYSTICK

on-chip

systick

UART

on-chip

serial port-polling; serial port-interrupt

PINMUX

on-chip

pinmux

GPIO

on-chip

gpio

WATCHDOG

on-chip

watchdog

TIMER

on-chip

timer

Other hardware features are not currently supported by the port. See the V2M Musca Website for a complete list of V2M Musca board hardware features.

The default configuration can be found in the defconfig file: boards/arm/v2m_musca/v2m_musca_defconfig.

Interrupt Controller

Musca is a Cortex-M33 based SoC and has 15 fixed exceptions and 77 IRQs.

A Cortex-M33-based board uses vectored exceptions. This means each exception calls a handler directly from the vector table.

Zephyr provides handlers for exceptions 1-7, 11, 12, 14, and 15, as listed in the following table:

Exc#

Name

Remarks

Used by Zephyr Kernel

1

Reset

system initialization

2

NMI

system fatal error

3

Hard fault

system fatal error

4

MemManage

MPU fault

system fatal error

5

Bus

system fatal error

6

Usage fault

Undefined instruction, or switch attempt to ARM mode

system fatal error

7

SecureFault

Unauthorized access to secure region from ns space

system fatal error

8

Reserved

not handled

9

Reserved

not handled

10

Reserved

not handled

11

SVC

context switch and software interrupts

12

Debug monitor

system fatal error

13

Reserved

not handled

14

PendSV

context switch

15

SYSTICK

system clock

16

Reserved

not handled

17

Reserved

not handled

18

Reserved

not handled

Pin Mapping

The ARM V2M Musca Board has 4 GPIO controllers. These controllers are responsible for pin-muxing, input/output, pull-up, etc.

All GPIO controller pins are exposed via the following sequence of pin numbers:

  • Pins 0 - 15 are for GPIO 0

  • Pins 16 - 31 are for GPIO 1

Mapping from the ARM V2M Musca Board pins to GPIO controllers:

  • D0 : P0_0

  • D1 : P0_1

  • D2 : P0_2

  • D3 : P0_3

  • D4 : P0_4

  • D5 : P0_5

  • D6 : P0_6

  • D7 : P0_7

  • D8 : P0_8

  • D9 : P0_9

  • D10 : P0_10

  • D11 : P0_11

  • D12 : P0_12

  • D13 : P0_13

  • D14 : P0_14

  • D15 : P0_15

  • D16 : P1_0

  • D17 : P1_1

  • D18 : P1_2

  • D19 : P1_3

  • D20 : P1_4

  • D21 : P1_5

  • D22 : P1_6

  • D23 : P1_7

  • D24 : P1_8

  • D25 : P1_9

  • D26 : P1_10

  • D27 : P1_11

  • D28 : P1_12

  • D29 : P1_13

  • D30c : P1_14

  • D31 : P1_15

Peripheral Mapping:

  • UART_0_RX : D0

  • UART_0_TX : D1

  • SPI_0_CS : D10

  • SPI_0_MOSI : D11

  • SPI_0_MISO : D12

  • SPI_0_SCLK : D13

  • I2C_0_SCL : D14

  • I2C_0_SDA : D15

  • UART_1_RX : D16

  • UART_1_TX : D17

  • SPI_1_CS : D18

  • SPI_1_MOSI : D19

  • SPI_1_MISO : D20

  • SPI_1_SCK : D21

  • I2C_1_SDA : D22

  • I2C_1_SCL : D23

For mode details please refer to Musca Technical Reference Manual (TRM).

RGB LED

Musca has a built-in RGB LED connected to GPIO[4:2] pins.

  • Red LED connected at GPIO[2] pin,with optional PWM0.

  • Green LED connected at GPIO[3] pin,with optional PWM0.

  • Blue LED connected at GPIO[4] pin,with optional PWM0.

Note

The SCC registers select the functions of pins GPIO[4:2].

System Clock

V2M Musca has a 32.768kHz crystal clock. The clock goes to a PLL and is multiplied to drive the Cortex-M33 processors and SSE-200 subsystem. The default is 50MHz but can be increased to 170MHz maximum for the secondary processor (CPU1) via software configuration. The maximum clock frequency for the primary processor (CPU0) is 50MHz.

Serial Port

The ARM Musca processor has two UARTs. Both the UARTs have only two wires for RX/TX and no flow control (CTS/RTS) or FIFO. The Zephyr console output, by default, uses UART1.

Security components

  • Implementation Defined Attribution Unit (IDAU). The IDAU is used to define secure and non-secure memory maps. By default, all of the memory space is defined to be secure accessible only.

  • Secure and Non-secure peripherals via the Peripheral Protection Controller (PPC). Peripherals can be assigned as secure or non-secure accessible.

  • Secure boot.

  • Secure AMBA® interconnect.

Serial Configuration Controller (SCC)

The ARM Musca test chip implements a Serial Configuration Control (SCC) register. The purpose of this register is to allow individual control of clocks, reset-signals and interrupts to peripherals, and pin-muxing.

QSPI boot memory

Normal Musca-A test chip boot operation is from external QSPI 8MB flash memory. Only the lowest 256KB of QSPI memory is directly accessible. More memory is accessible through indirect addressing.

Programming and Debugging

Musca supports the v8m security extension, and by default boots to the secure state.

When building a secure/non-secure application, the secure application will have to set the idau/sau and mpc configuration to permit access from the non-secure application before jumping.

The following system components are required to be properly configured during the secure firmware:

  • AHB5 TrustZone Memory Protection Controller (MPC).

  • AHB5 TrustZone Peripheral Protection Controller (PPC).

  • Implementation-Defined Attribution Unit (IDAU).

For more details please refer to Corelink SSE-200 Subsystem.

Flashing

Building a secure only application

You can build applications in the usual way. Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b v2m_musca samples/hello_world

Open a serial terminal (minicom, putty, etc.) with the following settings:

  • Speed: 115200

  • Data: 8 bits

  • Parity: None

  • Stop bits: 1

Reset the board, and you should see the following message on the corresponding serial port:

Hello World! arm

Building a secure/non-secure with Trusted Firmware

The process requires five steps:

  1. Build Trusted Firmware (tfm).

  2. Import it as a library to the Zephyr source folder.

  3. Build Zephyr with a non-secure configuration.

  4. Merge the two binaries together and sign them.

  5. Concatenate the bootloader with the signed image blob.

In order to build tfm please refer to Trusted Firmware M Guide. Follow the build steps for AN521 target while replacing the platform with -DTARGET_PLATFORM=MUSCA_A and compiler (if required) with -DCOMPILER=GCC

Copy over tf-m as a library to the zephyr project source and create a shortcut for the secure veneers.

cp -r install/ $ZEPHYR_PROJECT/src/ext
cp $ZEPHYR_PROJECT/src/ext/install/export/tfm/veneers/s_veneers.o $ZEPHYR_PROJECT/src/ext

Build the Zephyr app in the usual way.

Uploading an application to V2M Musca

Applications must be converted to Intel’s hex format before being flashed to a V2M Musca. An optional bootloader can be prepended to the image. The QSPI flash base address alias is 0x200000.

The image offset is calculated by adding the flash offset to the bootloader partition size.

A third-party tool (srecord) is used to generate the Intel formatted hex image. For more information refer to the Srecord Manual.

srec_cat $BIN_BOOLOADER -Binary -offset $QSPI_FLASH_OFFSET $BIN_SNS -Binary -offset $IMAGE_OFFSET -o $HEX_FLASHABLE -Intel

# For a 64K bootloader IMAGE_OFFSET = $QSPI_FLASH_OFFSET + 0x10000
srec_cat $BIN_BOOLOADER -Binary -offset 0x200000 $BIN_SNS -Binary -offset 0x210000 -o $HEX_FLASHABLE -Intel

# For a 256K bootloader IMAGE_OFFSET = $QSPI_FLASH_OFFSET + 0x40000
srec_cat $BIN_BOOLOADER -Binary -offset 0x200000 $BIN_SNS -Binary -offset 0x240000 -o $HEX_FLASHABLE -Intel

Connect the V2M Musca to your host computer using the USB port. You should see a USB connection exposing a Mass Storage (MBED) and a USB Serial Port. Copy the generated zephyr.hex in the MBED drive.

Reset the board, and you should see the following message on the corresponding serial port:

Hello World! arm