UART TX_CALLBACK_SIZE question

Hi Dialog Engineer,

I am using the DSPS application firmware as my baseline code to start with.
我有一个DA通过UART线路与外部MCU通信。UART的波特率为56.7kbps。

I have implemented two functions to send data across from the DA to the external MCU.

功能1：
-DA通电后，此功能从闪存读取数据，并通过UART线路下载外部MCU固件。由于外部MCU实际上可以启动并使用其固件运行，因此此功能始终100%正常工作。代码如下：

//从闪存地址“address”和“size”读取QPI固件/表&
// write it out the UART channel(s) where the QPI(s) attached to
void user_sps_qpi_fw_upload(unsigned int address) {

字节buf[2]；
// read the firmware size in bytes stored in flash from the Host UI flash program.
//固件len是flash中每个FW地址部分的前两个字节
unsigned int fwLen;
if(spi_flash_read_data(buf, address, USER_FLASH_QPI_FWSIZE_HDR) == USER_FLASH_QPI_FWSIZE_HDR) {
fwLen = (buf[0] << 8) | buf[1];
address += USER_FLASH_QPI_FWSIZE_HDR;
}
无符号字符数据\u ptr[用户\u FLASH \u QPI \u CI \u BLK \u SIZE]；
//计算闪存读取次数。每次读取的字节数为USER\ FLASH\ QPI\ CI\ BLK\ u SIZE字节
int n = fwLen/USER_FLASH_QPI_CI_BLK_SIZE + 1;
对于（int i=0；i// read the QPI FW from Flash. This can be FW, Degamma Table, LUM Tables
unsigned int ret = spi_flash_read_data(data_ptr, address + i*USER_FLASH_QPI_CI_BLK_SIZE,
USER_FLASH_QPI_CI_BLK_SIZE);
uart2\写入（数据\ ptr、用户\闪存\ QPI\ CI\ BLK\大小，NULL）；
uart2_finish_transfers();
}
}

- In this function, I am reading USER_FLASH_QPI_CI_BLK_SIZE = 256 bytes at a time from Flash and write over the UART2.

功能2：
-此函数读取从BLE线路传入的数据，并通过UART2总线将其发送到外部MCU。代码如下：

void user_ble_push(uint8_t* wrdata, uint16_t write_amount)
{
ASSERT_ERR(wrdata != NULL);
断言错误（写入金额！=0);

bool send_flow_off = false;

// write the BLE "data" to the peripheral buffer "ble_to_periph_buffer"
用户缓冲区写入项（&B）到缓冲区，wrdata，写入量；

//check if buffer is almost full and issue to send a XOFF if so
send\u flow\u off=user\u check\u buffer\u most\u full（&ble\u to\u periph\u buffer）；

//if XOFF must be send, send asap
if（发送流）{
用户发送流控制（流关闭）；
}
//start transmitting
__禁用irq（）；

if(!uart_qpi_tx_callbackbusy) {
uart\u qpi\u tx\u callbackbusy=真；
uart\u qpi\u tx\u回调（uart\u STATUS\u INIT）；
}
__启用\u irq（）；
}

-此函数是DSPS示例应用程序固件的一部分。我把它修改成我们自己的应用程序。uart\u qpi\u tx\u callback（）与DSPS示例中的内容相同。以下是此功能的代码，供您参考：

static void uart_qpi_tx_callback(uint8_t res)
{
static uint8_t size=0;
uint8\u t*periph\u tx\u ptr=NULL；

//函数在未运行时从uart transmit isr或应用程序调用
开关（res）
{
case UART_STATUS_OK:
//获取数据和指针
size=user\u periph\u pull（&periph\u tx\u ptr，size）；
break;
案例UART\状态\初始化：
size=user\u buffer\u read\u address（&ble\u to\u periph\u buffer，&periph\u tx\u ptr，tx\u CALLBACK\u size）；
break;
default:
断言错误（0）//错误：从未知源调用回调
}
//if there is data available, send data over periph
if(size > 0) {
uart2\ U写（外围发送\ ptr、大小和uart\ qpi\ U发送\ U回调）；
return;
}
//缓冲区中没有数据，因此回调已完成
uart\u qpi\u tx\u callbackbusy=false；
}

我对以上两个功能的问题：

1.在函数1中，我实际使用的是大小为256字节的UART写入。我知道TX FIFO的大小只有16个字节。为什么我的案子会这样。我不是在抱怨。我只是想更好地理解它。

2.在函数二,我有问题发送任何东西more than 16 bytes to the external MCU. If I sent 16 bytes or less, the MCU received everything. If I sent a packet that is more than 16 bytes, the bytes beyond the 16th byte will not be received. However, if I were to step into the uart2_write() function one line at a time and walk through the uart2_thr_empty_isr() inside uart2_write(), I can see all the data and the data will end up be received by the external MCU correctly. This will happen every time. If I step into the code, it will work. If I let the code run, It will fail every time.

Please let me know what you see and explain to me what's going on?

谢谢你的关注，
--Khai