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In The Mix with Intermix

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Adrian Nelson
Adrian Nelson

Pic Serial Uart C Source Code

This sample app enumerates all serial devices connected to the device and displays the list in the ListBox ConnectDevices. The following code connects and configure the selected device ID and creates a SerialDevice object.

pic serial uart c source code

Reading input from serial port is done by Listen() invoked right after initialization of the serial port. We do this in the sample code by creating an async read task using the DataReader object that waits on the InputStream of the SerialDevice object.

- Serial Flash Downloader (in SW-DK-TM4C123G-UG.) -sflash [OPTION]... [INPUT FILE]Description:Downloads a firmware image to a Tiva board using a UART connection to the TivaWare SerialFlash Loader or the TivaWare Boot Loader. This has the same capabilities as the serialdownload portion of the LM Flash Programmer tool.The source code for this utility is contained in tools/sflash, with a pre-built binary contained in tools/bin.

This demo is step two, you can find step one in our wiki, or check out the previous post. It shows how to setup the PIC to communicate with the FT232RL serial-to-USB IC over , and establish communication with your computer over the com terminal. The code below is broken up and explained section by section.

Continuous loop//Main Loop while(1) //wait for byte from USB to serial converter while(U1STAbits.URXDA == 0); c=U1RXREG;//get byte //wait for empty spot in transmit buffer while(U1STAbits.UTXBF == 1); //echo received character back to USB to serial converter U1TXREG = c; This code is executed in a continuous loop. The Bus pirate waits for one character to be sent to it via terminal, and once received the same character is echoed back to the terminal.

We want to publish your embedded source code for the benefit on the PIC community. Send it to support@microchipc.comand I will post it on the site, together with recognition of your name and website.

This code was used to drive a demo board that I made for a University of Canterbury demonstration day. From readme.txt: The demo board consisted of a 16F84, five 240V 3A solid state relays, an RS-232 port, a Dallas 1-wire interface port (using a RJ-11/12 connector), and a number of LEDs ... The archive contains the Hi-Tech C source code, Protel 99 schematic and pcb files, and .jpg schematic.

From readme.txt: The DALLAS DS1821 is a 3 pin digital thermostat that can have its trigger points programmed using the Dallas 1-wire interface. The need arose for this programmer when we had to replace the bi-metal thermostat controls from some fridges in the department for safety reasons. The DS1821 was the ideal replacement, the combination of small size, low operation voltage (3-5 volts) and operates to pre programmed settings that couldn't be changed unless you had a special programmer. Hence the birth of the DS1821 Programmer project. This project uses the 1-wire and I2C routines.The Turn On, Turn Off and Polarity values can be programmed using this code. There are 3 buttons, 'Menu', '+', and '-' to allow adjustments. The Data is displayed on a 4 digit I2C LCD controlled by a PCF8577 (Philips). Archive includes Hi-Tech C source code, schematics, and more.

Sometimes it is useful to have access to a larger amount of non-volatile storage than is available onboard the PIC. A serial accessed eeprom can be the best way to do this but they are usually only available in sizes up to 512Kbits. The 24LC256 is a 256Kbit eeprom avaialble from microchip and is what these functions are designed to work with although they should work with any size and speed of eeprom with suitable modification of the loops. This is just the functions you need to get some code working and then drop these in.

The MMC card has quite a large block size for writing, I think at the moment it is at least 512Bytes although I think I saw something about a new version of the specifcation that is more flexible. But at the moment this means that you need to buffer 512Bytes and write them all in one go, the eeprom code (above) is ideal for this. The write_block function just writes the lowest 512Bytes from the eeprom to the MMC. The same is true when reading the card and in my current application I only need to read the data to a PC so the read_block function just outputs every byte to RS232 although it wouldn't be hard to insert some processing or pass each byte to whatever function you wanted. This is just the functions you need to get some code working and then drop these in. MMC source in CCS C

"Attached please find another application for using joystick commonly found in game pad, mobile phones, etc. It is nothing more than individual tactile keys. There is a .pdf explaining the source code as well. Working on a dev board for PIC24 series. It will come with a 2.2" TFT color LCD. Designed for the C18 compiler." Original hardware obtained from

MniBasic is a full basic interpreteter for the PIC18, PIC24, and PIC32. It is written in C. By examining the source code, you can work out how to use almost any peripheral on the PIC18, PIC24 or PIC32. Example peripheral source code includes, but is not limited to, RS232, PWM, timers, LCD, port control, SPI, I2C, ethernet (under development), etc.

This is another routine that I want to share. This is the interrupt driven serial routine with circular FIFO for any PIC16x micro with a hardware UART. Compiled with Hi-Tech C. Since this is unbuffered, so I added a software FIFO. The FIFO management is quite lean and fast but required the size of the buffer to be power of 2 (2^x). This is because FIFO roll-over uses bit-wise AND of (buffer_size - 1). This reduces code size due to that no more conditionals to test pointers overflowing the buffer.

ASCII - Short for the American Standard Code for Information Interchange's character encoding scheme, ASCII encodes special characters from our keyboards and converts them to 7-bit binary integers that can be recognized by a number of programs and devices. ASCII charts are very helpful when working with serial terminals.

YAT is implemented in C#.NET using Windows.Forms. The source code is implemented in a very modular way. Utilities and I/O sub-systems can also be used independent on YAT, e.g. for any other .NET based application that needs serial communication, command line handling or just a couple of convenient utilities.Testing is done using an NUnit based test suite. Project documentation is done in OpenOffice. For more details and contributions to YAT, refer to Help > About.

The Arduino has one dedicated UART, which is just the fancy name for the serial TX and RX lines. It is over these two lines that the Arduino gets programmed. Thus, when working with the Arduino (or other microcontrollers) it's best to avoid using these lines to communicate with other serial devices, especially if you are developing your code and need to upload frequently.

IntroductionThis application note discusses how to build an inexpensive microprocessor circuit to allow a PC to communicate with a 2-wire device using its serial port. In addition to providing general insight on designing hardware, firmware and software to enable PCs to communicate with ICs, a complete PIC microprocessor reference design is presented to show how PC applications can be built around 2-wire devices. The reference design includes a complete schematic, firmware, and a low level C++ serial port code to jump-start any application that would like to incorporate 2-wire devices. The schematic, firmware, and software can be downloaded from Dallas Semiconductor's FTP site.

UARTs are used to maintain the timing of the communication while sending and receiving data. Many, but not all, microprocessors contain an RS232-compliant hardware UART. In addition to handling the timing, a hardware UART handles the serialization of the data from bytes to a bit stream, and it sends/receives the start and stop control bits without software intervention. All of the above mentioned can be handled by a software UART, but it generally must be at slower baud rates, and it can take a significant portion of the microprocessor's time to handle just the serial port communication. Conventional wisdom states it is generally better to buy the microprocessor with hardware UART. It allows efficient interrupt driven code to control the serial port peripheral, it tends to be more reliable, and the cost increase is generally minor due to the fact RS232 ports are very commonplace.

One important thing to consider when using a hardware UART is to use either use an oscillator or crystal with a frequency that will work with the microprocessor's baud rate generator. Baud rate generators generally use the clock frequency divided by a power of 2 to set the baud rate. Clock frequencies that are fractions or multiples of 11.0592MHz are generally suitable for this task. Once a crystal frequency has been chosen, the baud error should be calculated using the equation in the microprocessor's datasheet. If it is greater than 3%, it is likely communications will not be able to be established between the microprocessor and the PC. Also, a microprocessor using a resistor/capacitor (RC) clock source will most likely not be able to maintain serial communications due to fact the frequency of operation is likely to drift more than 3%. Since the baud rate error will follow the percentage change in the microprocessors clock frequency, this poses the same problem as having a 3% static baud rate error.

Since the 2-wire routines are provided for customers, the most of the details of the implementation will not be discussed in this application note. One thing that should be mentioned is the serial port code included will only work in a Window's environment (Windows NT 3.1, Windows 95, or subsequent versions of either). If a different programming language or operating system is desired, the communications software will have to be rewritten to accommodate the OS and language requirements. The easiest way to do this would be to look at the provided C++ code to see what must be sent and what is received while communicating with the firmware. Then mimic the transactions with the new software. The serial port settings required to establish communication are 57600 baud, 1 stop bit, and no parity.Building Application Hardware and PC Software Using the Reference DesignThere are four tasks to complete to build an application based on the PIC reference design. Program the PIC16LF628 microprocessor with the dsio.hex file available on the FTP site. Use either the PICSTART Plus programmer available from Microchip or an engineering programmer such as ones available from BP Microsystems. Build the circuit shown in the detailed schematic, which is available on the FTP site. If it is desirable to have the ability to change the firmware at a later time, make sure there is a way to isolate MCLR, VCC, RB6, and RB7 of the microprocessor. These are the pins used to in-circuit program the microprocessor. If a surface mount version of the PIC is being used, it can be more convenient to in-circuit program the PIC than to find a suitable adapter socket to work with the programmer's socket. Download the C++ code (DSIOLIB1.cpp, DSIOLIB.h, DSPIC.cpp, DSPIC.h), which is available on the FTP site. Write the application software. Include the four files listed above in the project, and add a #include "DSPIC.h" directive at the top of the software. Instantiate a member of the CdsPic class in global space. It is done in global space for two reasons. It will allow all of the program's subroutines access to the 2-wire functions, and only a single instance of this class is allowed the application. If a second instance of the class is opened it will not be able to open the serial port controlled by the prior instance, and therefore it will not be able to communicate with the PIC. After the class is instantiated, use the BoardPresent() member function to determine if the serial port was successfully opened. If the board is detected, continue to call the CdsPic member functions to perform 2-wire functions as needed, else inform the user that the PIC circuit was not found.An example 2-wire application was generated that can be downloaded from Dallas Semiconductor's FTP site. It is called DS2W, and it is a generic 2-wire tool that allows the user to communicate with 2-wire devices from Window's dialog box interface. The GUI for the program is shown below.


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