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PlatformMutex class hierarchy

The PlarformMutex class provides mutex stub functions in the absence of RTOS. This class enables you to use driver/application code when the RTOS is not present.

PlatformMutex class reference

Public Member Functions
void lock ()
void unlock ()

PlatformMutex example

The code below demonstrates usage of PlatformMutex.

#include "mbed.h"

PlatformMutex stdio_mutex;
Thread t2;
Thread t3;
void notify(const char* name, int state) {
    printf("%s: %d\n\r", name, state);

void test_thread(void const *args) {
    while (true) {
        notify((const char*)args, 0); wait(1);
        notify((const char*)args, 1); wait(1);

int main() {
    t2.start(callback(test_thread, (void *)"Th 2"));
    t3.start(callback(test_thread, (void *)"Th 3"));

    test_thread((void *)"Th 1");

Mbed OS uses the PlatformMutex class instead of the RTOS mutex for all drivers. For example, please see AnalogIn, BusOut, SPI, Serial and I2C.

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