Избавился от SPL.

lib/max7219.c

@@ -55,22 +55,22 @@ void MAX7219_Config(void) {
 void MAX7219_WriteData(max7219_reg_t reg, uint8_t data)
 {
     /*!< Wait wait until the completion of the transfer. */
-    while (SPI_GetFlagStatus(SPI_FLAG_BSY) == SET) {}
+    while ((SPI->SR & 0x80) != RESET);
     /* Down LOAD pin */
     SPI_LOAD_PORT->ODR &= (uint8_t)(~SPI_LOAD);
 
     /*!< Wait until the transmit buffer is empty */
-    while (SPI_GetFlagStatus(SPI_FLAG_TXE) == RESET) {}
+    while ((SPI->SR & 0x02) == RESET);
     /* Send the register where the data will be stored */
     SPI->DR = reg; /* Write in the DR register the data to be sent*/
 
     /*!< Wait until the transmit buffer is empty */
-    while (SPI_GetFlagStatus(SPI_FLAG_TXE) == RESET) {}
+    while ((SPI->SR & 0x02) != RESET);
     /* Send the data to be stored */
     SPI->DR = data; /* Write in the DR register the data to be sent*/
 
     /*!< Wait wait until the completion of the transfer. */
-    while (SPI_GetFlagStatus(SPI_FLAG_BSY) == SET) {}
+    while ((SPI->SR & 0x80) != RESET);
     /* Up LOAD pin */
     SPI_LOAD_PORT->ODR |= SPI_LOAD;
 }