diff --git a/lib/sensor_sdm120.c b/lib/sensor_sdm120.c
index f5eb97c..ba9b058 100644
--- a/lib/sensor_sdm120.c
+++ b/lib/sensor_sdm120.c
@@ -301,7 +301,7 @@ float sensor_sdm120_measurement_decode(void)
 /** USART interrupt service routine called when data has been transmitted or received */
 void USART_ISR(SENSOR_SDM120_USART)(void)
 {
-	if (usart_get_interrupt_source(USART(SENSOR_SDM120_USART), USART_SR_TXE)) { // data has been transmitted
+	if (usart_get_flag(USART(SENSOR_SDM120_USART), USART_SR_TXE)) { // data has been transmitted
 		if (tx_used) { // not all bytes transmitted
 			usart_send(USART(SENSOR_SDM120_USART),tx_buffer[--tx_used]); // transmit next byte (clears flag)
 		} else { // all bytes transmitted
@@ -310,7 +310,7 @@ void USART_ISR(SENSOR_SDM120_USART)(void)
 			USART_CR1(USART(SENSOR_SDM120_USART)) |= USART_CR1_TCIE; // enable transfer complete interrupt
 		}
 	}
-	if (usart_get_interrupt_source(USART(SENSOR_SDM120_USART), USART_SR_TC)) { // data has been completely transmitted
+	if (usart_get_flag(USART(SENSOR_SDM120_USART), USART_SR_TC)) { // data has been completely transmitted
 		USART_CR1(USART(SENSOR_SDM120_USART)) |= USART_CR1_TCIE; // disable transfer complete interrupt
 		USART_SR(USART(SENSOR_SDM120_USART)) &= ~USART_SR_TC; // clear flag
 		timeout = TIMEOUT_END; // select wait time after sending data
@@ -318,7 +318,7 @@ void USART_ISR(SENSOR_SDM120_USART)(void)
 		timer_set_counter(TIM(SENSOR_SDM120_TIMER), 0); // reset timer counter to get preset waiting time
 		timer_enable_counter(TIM(SENSOR_SDM120_TIMER)); // wait
 	}
-	if (usart_get_interrupt_source(USART(SENSOR_SDM120_USART), USART_SR_RXNE)) { // data has been received
+	if (usart_get_flag(USART(SENSOR_SDM120_USART), USART_SR_RXNE)) { // data has been received
 		if (gpio_get(GPIO_PORT(SENSOR_SDM120_REDE_PIN),GPIO_PIN(SENSOR_SDM120_REDE_PIN))) { // not in receiver mode
 			USART_SR(USART(SENSOR_SDM120_USART)) &= ~USART_SR_RXNE; // clear flag, ignore received data
 		} else if (rx_used<LENGTH(rx_buffer)) { // receiving response