有關UART問題

板子是L053R8

程式寫完好像無法傳輸

不清楚問題在哪?

#include "main.h"
#include "dma.h"
#include "usart.h"
#include "gpio.h"

void SystemClock_Config(void);

uint8_t temp1[]="hello";
uint8_t temp2[8];

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
if (huart==&huart1) 
HAL_UART_Transmit_DMA(&huart1,temp2,sizeof(temp2));
}
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
if (huart==&huart1)
HAL_GPIO_TogglePin(GPIOA,GPIO_PIN_0);
}

int main(void)
{

HAL_Init();

SystemClock_Config();

MX_GPIO_Init();
MX_USART1_UART_Init();
MX_DMA_Init();

HAL_UART_Receive_DMA(&huart1,temp2,sizeof(temp2));

while (1)
{

HAL_UART_Transmit_DMA(&huart1,temp1,sizeof(temp1));
HAL_Delay(1000);


}