Single-chip computer serial communication RXD and TXD How to connect the detailed

http://blog.csdn.net/sdwuyulunbi/article/details/6632382

Believe that a lot of people on the microcontroller and computer or chip communication, RXD and txd How to connect more confused. Because in some circuit diagram, there are some direct connection method, there are some cross-linking method, let a person a bit puzzled.

The first thing to understand is the two concepts, DTE and DCE. DTE refers to data terminal equipment, the typical DTE is a computer and a microcontroller. DCE refers to the data communication equipment, the typical DCE is the modem. The Rxd and TXD in the RS232 serial standard are in the DTE position, not the DCE. Understand this, and then the following wiring method, it is very good to understand.

Single-chip microcomputer and computer serial communication, single-chip microcomputer RXD computer TXD, SCM TXD connected to the computer rxd.

(1) using the serial port straight line. When designing the circuit, the single-chip microcomputer's RXD connects the circuit board DB9 the TXD, the SCM TXD connects the circuit board DB9 RXD, the concrete realization may in the 232 level conversion chip the reverse connection.

(2) Use the Serial line crossover. Design circuit, because the serial line has been done cross, single-chip computer rxd Connection circuit board DB9 RXD, SCM TXD Connection circuit board DB9 Txd, are directly connected.

This can explain why some circuits use the direct connection method, some circuits use the crossover method, because the use of the serial line is different.

MCU and serial equipment (such as GPRS module, carrier chip, etc.) communication, will be rxd and TXD reverse, that is, the single-chip microcomputer RXD The TXD of the device, the txd of single-chip computer connection equipment RXD. (except for the RXD and SCM Rxd Direct connection, such as Huawei's EM310)

The above is only the development process of personal experience, what problems, but also hope to enlighten.

Single-chip computer serial communication RXD and TXD How to connect the detailed