diff --git a/src/systembus/systembus_uart.c b/src/systembus/systembus_uart.c
index e9bb943..8739bbc 100644
--- a/src/systembus/systembus_uart.c
+++ b/src/systembus/systembus_uart.c
@@ -100,8 +100,8 @@ int SysbusUart_Send(SYSBUS_UART *instPtr, SYSBUS_UART_FRAME *frame)
 {
 	ASSERT(instPtr != NULL);
 	ASSERT(frame != NULL);
-	uint8_t dLen, checkSum;
-	uint8_t sendLen;
+	uint8_t checkSum;
+	uint16_t dLen, sendLen;
 	uint8_t *sendBuff;
 	if (frame->len > UART_TXBUFF_MAX || frame->len == 0)
 	{
@@ -168,7 +168,8 @@ int SysbusUart_Recv(SYSBUS_UART *instPtr, SYSBUS_UART_FRAME *frame)
 	ASSERT(instPtr != NULL);
 	ASSERT(frame != NULL);
 
-	uint8_t dLen, dWLen, plLen, checkSum, checkSumCal;
+	uint16_t dLen, dWLen, plLen;
+	uint8_t checkSum, checkSumCal;
 	uint8_t *plBuff, *dBuff;
 	dLen = SYSTEMBUS_UART_mReadReg(instPtr->config.baseAddr, UART_RECV_CNT);
 	if (dLen == 0 || dLen > UART_TXBUFF_MAX)
diff --git a/src/systembus/systembus_uart.h b/src/systembus/systembus_uart.h
index a86c290..b5105de 100644
--- a/src/systembus/systembus_uart.h
+++ b/src/systembus/systembus_uart.h
@@ -96,7 +96,7 @@ typedef struct
 	uint16_t len;
 	uint8_t checkSum;
 	uint8_t isValid;
-	uint8_t data[256];
+	uint8_t data[1024];
 } SYSBUS_UART_FRAME;
 
 /************************** Function Prototypes ******************************/