diff --git a/ked/csl/stm32f042/Device/hardwareDescription.h b/ked/csl/stm32f042/Device/hardwareDescription.h
index 70dafba..7018153 100644
--- a/ked/csl/stm32f042/Device/hardwareDescription.h
+++ b/ked/csl/stm32f042/Device/hardwareDescription.h
@@ -236,7 +236,10 @@ typedef enum{
 	SPI_CH_2
 } spiCH_t;
 
-
+static const uint32_t spiBase_Addr_List[MAX_SPI_CHANNEL_COUNT] =  {
+	SPI1_BASE,
+	SPI2_BASE
+};
 
 
 #ifdef __cplusplus
diff --git a/ked/csl/stm32f042/Src/spi.c b/ked/csl/stm32f042/Src/spi.c
index 7de72d1..f272ac1 100644
--- a/ked/csl/stm32f042/Src/spi.c
+++ b/ked/csl/stm32f042/Src/spi.c
@@ -1,5 +1,7 @@
 #include "spi.h"
 
+#define SPI_BASE	((SPI_TypeDef *)spiBase_Addr_List[spi_hw_ch])
+
 // https://controllerstech.com/spi-using-registers-in-stm32/
 
 void spi_initMater(spiCH_t_spi_hw_ch)
@@ -25,5 +27,14 @@ void spi_initMater(spiCH_t_spi_hw_ch)
 
 uint8_t spi_trx(spiCH_t_spi_hw_ch, uint8_t tx_data)
 {
-	return 0;
+	// wait for SPY ready
+	while((SPI_BASE->SR) & (1 << 7));
+
+	// load tx data
+	SPI_BASE->DR = tx_data;
+
+	// Wait for RXNE flag to be set which indicates transmit complete
+	while(!((SPI_BASE->SR) & (1<<0));
+	
+	return SPI_BASE->DR;
 }