Mailbox

Overview

The MCUXpresso SDK provides a peripheral driver for the Mailbox module of MCUXpresso SDK devices.

The mailbox driver API provide:

• init/deinit: MAILBOX_Init()/MAILBOX_Deinit()
• read/write from/to mailbox register: MAILBOX_SetValue()/MAILBOX_GetValue()
• set/clear mailbox register bits: MAILBOX_SetValueBits()/MAILBOX_ClearValueBits()
• get/set mutex: MAILBOX_GetMutex()/MAILBOX_SetMutex()

Typical use case

Example of code on primary core, which cause interrupt on secondary core by writing to mailbox register.

int main(void)
{
    /* Init Mailbox */
    MAILBOX_Init(MAILBOX);

    uint32_t message = 1;

    /* Write message to CM0+ mailbox register - it causes interrupt on CM0+ core */
    MAILBOX_SetValue(MAILBOX, kMAILBOX_CM0Plus, message);
}

Example of code on secondary core to handle interrupt from primary core.

void MAILBOX_IRQHandler()
{
    /* Read message from CM0+ mailbox register, sent by primary core */
    uint32_t message;
    message = MAILBOX_GetValue(MAILBOX, kMAILBOX_CM0Plus);

    /* Clear mailbox CM0+ mailbox register */
    MAILBOX_ClearValueBits(MAILBOX, kMAILBOX_CM0Plus, 0xffffffff);
}

int main(void)
{
    /* Init Mailbox */
    MAILBOX_Init(MAILBOX);

    /* Enable mailbox interrupt */
    NVIC_EnableIRQ(MAILBOX_IRQn);

    while (1)
    {
        __WFI();
    }
}

Example of code to get/set mutex.

/* Shared variable by both cores */
volatile uint32_t g_shared = 0;

int main(void)
{
    /* Init Mailbox */
    MAILBOX_Init(MAILBOX);

    /* The core try get the mailbox mutex */
    while (MAILBOX_GetMutex(MAILBOX) == 0)
    {}

    /* The core has mutex, can change shared variable g_shared */
    g_shared++;

    /* Set mutex to allow access other core to shared variable */
    MAILBOX_SetMutex(MAILBOX);
}

Files
file	fsl_mailbox.h

Enumerations
enum	mailbox_cpu_id_t
	CPU ID.

Functions
static void	MAILBOX_SetValue (MAILBOX_Type *base, mailbox_cpu_id_t cpu_id, uint32_t mboxData)
	Set data value in the mailbox based on the CPU ID. More...
static uint32_t	MAILBOX_GetValue (MAILBOX_Type *base, mailbox_cpu_id_t cpu_id)
	Get data in the mailbox based on the CPU ID. More...
static void	MAILBOX_SetValueBits (MAILBOX_Type *base, mailbox_cpu_id_t cpu_id, uint32_t mboxSetBits)
	Set data bits in the mailbox based on the CPU ID. More...
static void	MAILBOX_ClearValueBits (MAILBOX_Type *base, mailbox_cpu_id_t cpu_id, uint32_t mboxClrBits)
	Clear data bits in the mailbox based on the CPU ID. More...
static uint32_t	MAILBOX_GetMutex (MAILBOX_Type *base)
	Get MUTEX state and lock mutex. More...
static void	MAILBOX_SetMutex (MAILBOX_Type *base)
	Set MUTEX state. More...

Driver version
#define	FSL_MAILBOX_DRIVER_VERSION   (MAKE_VERSION(2, 0, 0))
	MAILBOX driver version 2.0.0. More...

MAILBOX initialization
static void	MAILBOX_Init (MAILBOX_Type *base)
	Initializes the MAILBOX module. More...
static void	MAILBOX_Deinit (MAILBOX_Type *base)
	De-initializes the MAILBOX module. More...

Macro Definition Documentation

#define FSL_MAILBOX_DRIVER_VERSION   (MAKE_VERSION(2, 0, 0))

Function Documentation

static void MAILBOX_Init ( MAILBOX_Type *  base )

inlinestatic

This function enables the MAILBOX clock only.

Parameters

base	MAILBOX peripheral base address.

static void MAILBOX_Deinit ( MAILBOX_Type *  base )

inlinestatic

This function disables the MAILBOX clock only.

Parameters

base	MAILBOX peripheral base address.

static void MAILBOX_SetValue ( MAILBOX_Type *  base, mailbox_cpu_id_t  cpu_id, uint32_t  mboxData  )

inlinestatic

Parameters

base	MAILBOX peripheral base address.
cpu_id	CPU id, kMAILBOX_CM0Plus is M0+ or kMAILBOX_CM4 is M4.
mboxData	Data to send in the mailbox.

Note

Sets a data value to send via the MAILBOX to the other core.

static uint32_t MAILBOX_GetValue ( MAILBOX_Type *  base, mailbox_cpu_id_t  cpu_id  )

inlinestatic

Parameters

base	MAILBOX peripheral base address.
cpu_id	CPU id, kMAILBOX_CM0Plus is M0+ or kMAILBOX_CM4 is M4.

Returns

Current mailbox data.

static void MAILBOX_SetValueBits ( MAILBOX_Type *  base, mailbox_cpu_id_t  cpu_id, uint32_t  mboxSetBits  )

inlinestatic

Parameters

base	MAILBOX peripheral base address.
cpu_id	CPU id, kMAILBOX_CM0Plus is M0+ or kMAILBOX_CM4 is M4.
mboxSetBits	Data bits to set in the mailbox.

Note

Sets data bits to send via the MAILBOX to the other core. A value of 0 will do nothing. Only sets bits selected with a 1 in it's bit position.

static void MAILBOX_ClearValueBits ( MAILBOX_Type *  base, mailbox_cpu_id_t  cpu_id, uint32_t  mboxClrBits  )

inlinestatic

Parameters

base	MAILBOX peripheral base address.
cpu_id	CPU id, kMAILBOX_CM0Plus is M0+ or kMAILBOX_CM4 is M4.
mboxClrBits	Data bits to clear in the mailbox.

Note

Clear data bits to send via the MAILBOX to the other core. A value of 0 will do nothing. Only clears bits selected with a 1 in it's bit position.

static uint32_t MAILBOX_GetMutex ( MAILBOX_Type *  base )

inlinestatic

Parameters

base	MAILBOX peripheral base address.

Returns

See note

Note

Returns '1' if the mutex was taken or '0' if another resources has the mutex locked. Once a mutex is taken, it can be returned with the MAILBOX_SetMutex() function.

static void MAILBOX_SetMutex ( MAILBOX_Type *  base )

inlinestatic

Parameters

base	MAILBOX peripheral base address.

Note

Sets mutex state to '1' and allows other resources to get the mutex.