diff --git a/components/esp8266_wrapper/esp8266_wrapper.c b/components/esp8266_wrapper/esp8266_wrapper.c
index c4bbb1a..5f00fe7 100644
--- a/components/esp8266_wrapper/esp8266_wrapper.c
+++ b/components/esp8266_wrapper/esp8266_wrapper.c
@@ -129,9 +129,10 @@ int i2c_slave_read (uint8_t bus, uint8_t addr, const uint8_t *reg,
 
 // esp-open-rtos SPI interface wrapper
 
-#define SPI_MAX_BUS 3   // ESP32 features three SPIs (SPI, HSPI and VSPI)
+#define SPI_MAX_BUS 3   // ESP32 features three SPIs (SPI_HOST, HSPI_HOST and VSPI_HOST)
 #define SPI_MAX_CS  34  // GPIO 33 is the last port that can be used as output
 
+SemaphoreHandle_t spi_semaphores[SPI_MAX_BUS] = { 0 };
 spi_device_handle_t spi_handles[SPI_MAX_CS] = { 0 };
 
 bool spi_bus_init (spi_host_device_t host, uint8_t sclk , uint8_t miso, uint8_t mosi)
diff --git a/components/esp8266_wrapper/esp8266_wrapper.h b/components/esp8266_wrapper/esp8266_wrapper.h
index 35ddcde..b76e6af 100644
--- a/components/esp8266_wrapper/esp8266_wrapper.h
+++ b/components/esp8266_wrapper/esp8266_wrapper.h
@@ -99,6 +99,13 @@ bool spi_device_init (uint8_t bus, uint8_t cs);
 size_t spi_transfer_pf(uint8_t bus, uint8_t cs, 
                        const uint8_t *mosi, uint8_t *miso, uint16_t len);
 
+extern SemaphoreHandle_t spi_semaphores[];
+
+// platform specific definitions
+#define spi_semaphore_take(d) if (d) xSemaphoreTake(spi_semaphores[d->bus], portMAX_DELAY)
+#define spi_semaphore_give(d) if (d) xSemaphoreGive(spi_semaphores[d->bus])
+#define spi_semaphore_init(d) if (d && !spi_semaphores[d->bus]) spi_semaphores[d->bus] = xSemaphoreCreateMutex()
+
 /*
  * freertos api wrapper
  */