为什么AI8H8K64U使用DMA发送时DMA_URnT_DONE始终为0
<pre><code class="language-c">#include <stdint.h>#include <stdio.h>
#include "stdio_dma.h"
#ifdef configDMA_STDIO_UART_TX
static int8_t dmaUartTxBuffer;
__data static volatile uint8_t dmaUartTxHead = 0x00;
__data static volatile uint8_t dmaUartTxTail = 0x00;
static volatile __bit dmaUartTxBusy = 0;
void vInitalizeUart(void)
{
#if (configCPU_CLOCK_1T == 1)
AUXR |= 0x02; // 定时器时钟1T模式
const uint16_t uiTick = MCU_MAJOR_FOC / configUART_BAUDRATE / 4;
#else
AUXR &= 0xFB; // 定时器时钟12T模式
const uint16_t uiTick = MCU_MAJOR_FOC / configUART_BAUDRATE / 4 / 12;
#endif
const uint16_t uiInit = 0x10000 - uiTick;
TMR2= uiInit;
S2CON = 0x10;
AUXR |= 0x10;
}
void prvDmaUartTxStart(void)
{
dmaUartTxBusy = 1;
uint16_t ptr = (uint16_t)&dmaUartTxBuffer;
DMA_UART_TX_TXAH = (uint8_t)(ptr >> 8);
DMA_UART_TX_TXAL = (uint8_t)(ptr & 0xff);
uint8_t len = 0;
if (dmaUartTxHead < dmaUartTxTail) {
len = dmaUartTxTail - dmaUartTxHead;
} else {
len = configDMA_STDIO_UART_TX_SIZE - dmaUartTxHead;
}
DMA_UART_TX_AMNT = len;
DMA_UART_TX_STAT = 0;
DMA_UART_TX_CONF = 0x8f;
DMA_UART_TX_CTRL = 0xC0;
EA = 1;
}
void vDmaUartTxISR(void) __interrupt(VECTOR_DMA_UART_TX)
{
P6 = 0xf0;
// 清除DMA_UART_TX中断标志
DMA_UART_TX_STAT = 0;
// 更新发送缓冲区头指针
dmaUartTxHead = dmaUartTxHead + DMA_UART_TX_DONE + 1;
dmaUartTxHead = dmaUartTxHead % configDMA_STDIO_UART_TX_SIZE;
// 清除自定义DMA繁忙标志
dmaUartTxBusy = 0;
// 如果还有数据待发送，则重新启动DMA传输
if (dmaUartTxHead != dmaUartTxTail) {
prvDmaUartTxStart();
}
}
int putchar(int ch)
{
// 等待DMA发送缓冲区有空间
uint8_t next;
do {
next = dmaUartTxTail + 1;
next = next % configDMA_STDIO_UART_TX_SIZE;
} while (next == dmaUartTxHead);
dmaUartTxBuffer = ch;
dmaUartTxTail = next;
// 如果DMA传输未在进行中，则启动DMA传输
if (!dmaUartTxBusy) {
prvDmaUartTxStart();
}
return ch;
}
#endif // configSTDIO_UART_TX_DMA
</code></pre>
<p>如以上代码所示，我尝试在AI8H8K64U上使用DMA传输串口数据，但是串口助手中收到的数据如图所示：<br />
<img src="data/attachment/forum/202505/31/002457szedmssk2sed0z1k.png" alt="image.png" title="image.png" /></p>
<p>经反复调试发现，是DMA发送中断中，<code>DMA_UR2T_DONE</code>始终为0导致。换了其它几个串口也是一样的效果……<br />
现在求教大家，所有示例中似乎都没找到 <code>DMA_UR2T_DONE</code>用法，是我 <code>DMA_UR2T_DONE</code>使用姿势不太对吗？</p>
<hr />
<p>（为了切换串口方便，我重新定义了XSFR）</p>
<p><a href="forum.php?mod=attachment&aid=102140" title="attachment"><img src="/source/plugin/zhanmishu_markdown/template/editor/images/upload.svg" alt="upload" /> 附件：stdio_dma.h</a><a href="forum.php?mod=attachment&aid=102141" title="attachment"><img src="/source/plugin/zhanmishu_markdown/template/editor/images/upload.svg" alt="upload" /> 附件：stdio_dma.c</a></p>
DMA_UR2T_DONE这个寄存器问题我也遇到过，还是先不要使用这个~
使用DMA_UR2x_AMT设置的传输长度和DMA中断传输完成Flag.
https://www.stcaimcu.com/forum.p ... =1&extra=#pid157073
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