MAX232 is one of the most used UART-RS232 switch ICs. Clearly there is a need for a "converter" between the two.įortunately, we do not need to design this bridge ourselves because there are dedicated ICs. In UART standard (on AVR), level 1 corresponds to high voltage (5V, TTL) while for RS232 level 1 corresponds to low voltage (negative voltage, maybe -12V). Refer to the comparison example in Figure 2. In most cases, however, only three pins are used.Īs stated in AVR5-UART, the RS232 and UART standards are generally the same in terms of transmission, baud rate. The remaining pins can also be used if the user has some knowledge of the PC's register organization. These are three basic pins for RS232 communication and UART compatible on AVR. Most noticeable in the pins of the COM port is the 3 pin 0V SG (signal ground), TxD data transmitter pins and RxD data receiving pins. Need to understand main points about null modems and pinout RS232.įigure 1 shows two types of COM ports and Table 1 summarizes the functions of the ports. However, somewhere there is a 25-pin COM port, which is about the same as the LPT port, but it's a male, while the LPT port is female. COM ports on existing computers (where available) are mostly 9-pin male. However, with the robotics or control, the COM-RS232 is very popular for its simplicity and also because of. This standard is quite slow compared to USB. Today, with the emergence and "expansion" of the USB standard, the COM port (and either the LPT port or the parallel port) is disappearing.ĬOM port communication is RS232 serial communication. Write COM port program on PC (Visual C ++, Visual Basic)Ī COM port or Serial Port is a communications port that is part of the "aging" form of the PC, both desktops and laptops.Use functions in standard C export library such as printf, scanf.Create a virtual COM port on the PC for simulation purposes.Schematic diagram and function of the COM port pins on the computer.Specifically this article includes: Contents Comprehensive as I will guide you through the transition between AVR and PC, how to write program interface RS232 on the computer and on the AVR. It's simple because I'm going to use a rather "classic" interface to communicate between AVR and PC, RS232 interface via COM ports. This article will talk about how to communicate between AVR and PC in a simple but quite comprehensive way.
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