Purpose of "loop_until_bit_is_set(UCSRA, UDRE)" AVR Freaks AVR GCC forum - purpose of "loop_until_bit_is_set(UCSRA, UDRE)" ashishkedia1985 - Apr 07, 2008 - 04:39 PMPost subject: purpose of "loop_until_bit_is_set(UCSRA, UDRE)" what is the purpose of "loop_until_bit_is_set(UCSRA, UDRE);" and where is this function defined please can any one tell me about this???????????
Koshchi - Apr 07, 2008 - 04:44 PMPost subject: RE: purpose of "loop_until_bit_is_set(UCSRA, UDRE)&quo Quote: what is the purpose of "loop_until_bit_is_set(UCSRA, UDRE); It will loop until the bit is set. And where is this function defined It is probably not a function, but rather a macro. Using the USART of AVR Microcontrollers : Reading and Writing Data. Using the USART of AVR Microcontrollers : Reading and Writing Data Dec 29, 2008 Avinash AVR Tutorials, Code Libraries 101 Till now we have seen the basics of RS232 communication, the function of level converter and the internal USART of AVR micro.
After understanding the USART of AVR we have also written a easy to use function to initialize the USART. That was the first step to use RS232. Now we will see how we can actually send/receive data via rs232. So lets get started! USARTReadChar() : To read the data (char) from the USART buffer. This two functions will demonstrate the use of USART in the most basic and simplest way. Reading From The USART : USARTReadChar() Function. This function will help you read data from the USART. (See the full description of USART registers) char USARTReadChar() { //Wait untill a data is available while(! Writing to USART : USARTWriteChar() This function will help you write a given character data to the USART. UDR=some_data; //Goes to transmitter That's it! » MAX232 Serial level converter : SoDoItYourself.com. When communicating with various micro processors one needs to convert the RS232 levels down to lower levels, typically 3.3 or 5.0 Volts.
Here is a cheap and simple way to do that. Serial RS-232 (V.24) communication works with voltages -15V to +15V for high and low. On the other hand, TTL logic operates between 0V and +5V . Modern low power consumption logic operates in the range of 0V and +3.3V or even lower. Thus the RS-232 signal levels are far too high TTL electronics, and the negative RS-232 voltage for high can’t be handled at all by computer logic. This level converter uses a Max232 and five capacitors. The MAX232 from Maxim was the first IC which in one package contains the necessary drivers and receivers to adapt the RS-232 signal voltage levels to TTL logic. The requred parts: 1 x female serial port connector1 x max 2324 x 1uF capacitor1 x 10uF capacitorSoldering iron, wires, breadboard etc. Schematic. RS-232 vs. TTL Serial Communication. RS-232 vs.
TTL Serial Communication Skill Level: Beginner by Jimb0 | November 23, 2010 | 6 comments One of the tools we use most when debugging our projects is serial input/output. Serial is very easy to implement, and it allows you to send/receive any data you need from your microcontroller to a computer's serial port so it can be viewed using a terminal emulator. Most microcontrollers these days have built in UARTs (universally asynchronous receiver/transmitter) that can be used to receive and transmit data serially. The serial port on your computer (if it's lucky enough to have one, they're quickly becoming a relic) complies with the RS-232 (Recommended Standard 232) telecommunications standard. The more extreme voltages of an RS-232 signal help to make it less susceptible to noise, interference, and degradation.
This timing diagram shows both a TTL (bottom) and RS-232 signal sending 0b01010101 Solutions So, you may see where the problem lies in interfacing these two signals. 1.