本帖最后由 Xflyan 于 2012-4-6 13:38 编辑
最近在STM8S103上调MODBUS RTU，MODBUS的Serial通信字符帧长度为11bit，即无校验(NONE) + STOP_BIT_2 或 奇校验(ODD) + STOP_BIT_1 或 偶校验(EVEN) + STOP_BIT_1；但一个奇怪的问题就是，只要103的字符帧长度为11bit，前面的3选1，PC端不管用哪种方式发送(ODD/EVEN/MARK/SPACE + 1)，103居然都能够正确接收并返回，为此我还特意测了一下我PC端的发送序列，奇校验和偶校验时明显是不一样的，103这个情况似乎太强悍了:funk:，能解释下吗？为什么没有103没有提示校验错误？
UART1配置为 测试波特率为9600：
- void halUARTInit(u8 baudrate, u8 parity)
- {
- switch (parity) {
- case UART_PARITY_NONE:
- UART1->CR3 = 0x20; // STOP_BIT_2
- break;
-
- case UART_PARITY_EVEN:
- UART1->CR1 = UART1_CR1_PCEN | UART1_CR1_M;
- break;
-
- case UART_PARITY_ODD:
- UART1->CR1 = UART1_CR1_PCEN | UART1_CR1_PS | UART1_CR1_M;
- break;
-
- default:
- UART1->CR1 = UART1_CR1_PCEN | UART1_CR1_M;
- break;
- }
-
- switch (baudrate) {
- case UART_BR_115200:
- UART1->BRR2 = 0x0B; // 12MHz 115200:BRR=0x0068;
- UART1->BRR1 = 0x08; // 16MHz 115200:BRR=0x008B
- break;
-
- case UART_BR_57600:
- UART1->BRR2 = 0x06; // 12MHz 57600:BRR=0x00D0;
- UART1->BRR1 = 0x11; // 16MHz 57600:BRR=0x0116
- break;
-
- case UART_BR_38400:
- UART1->BRR2 = 0x01; // 12MHz 38400:BRR=0x0139;
- UART1->BRR1 = 0x1A; // 16MHz 38400:BRR=0x01A1
- break;
-
- case UART_BR_19200:
- UART1->BRR2 = 0x01; // 12MHz 19200:BRR=0x0271;
- UART1->BRR1 = 0x34; // 16MHz 19200:BRR=0x0341
- break;
-
- case UART_BR_9600:
- UART1->BRR2 = 0x03; // 12MHz 9600:BRR=0x04E2;
- UART1->BRR1 = 0x68; // 16MHz 9600:BRR=0x0683
- break;
- }
-
- UART1->CR2 |= UART1_CR2_TEN | UART1_CR2_REN;
- UART1->CR2 |= UART1_CR2_RIEN; // RX Interrupt Enable
- }
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