C program to Linux Serial port read write. Rate this: Please Sign up or sign in to vote. Hi all, I am new to C and linux. For your reference i have attached the send.c and receive.c code and also the output i am getting, can any one tell me what is wrong in this? Wide Temperature (-20°C +70°C). Character address code updated. This display uses a built-in PIC16F690 for serial communication. Syntax hexadecimal 0xFE 0x61 baud. PIC16F690 PWM c programming. Motor control and communications capability. The 20-pin family brings. PIC16F685/687/689/690 20-Pin DS41262A oper203-1760 DS41262A-page PIC16f690 example codes PIC16f690 spi example codes PIC16f690 example codes for Serial LCD Interface PIC16f687 spi example codes eeprom tutorial PIC16F687 Assembler.
The embedded C is the most popular programming language in the software field for developing electronic gadgets. Each processor is associated with embedded software. Plays a major role in performing specific functions by the processor. In our day-to-day life we frequently use many electronic devices such as washing machine, mobile phone, digital camera and so on will work based on microcontrollers that are programmed by embedded C. Embedded System ProgrammingThe C code written is more reliable, portable, and scalable; and in fact, much easier to understand. The first and foremost tool is the embedded software that decides operation of an embedded system.
Embedded C programming language is most frequently used for programming the microcontrollers. Embedded C Programming Tutorial (8051)For writing the program the embedded designers must have sufficient knowledge on hardware of particular processor or controllers as the embedded C programming is a fully hardware related programming technique. Programming TutorialEarlier, many embedded applications were developed by using assembly level programming. However, they did not provide portability to overcome this problem with the advent of various high level languages like C, COBOL and Pascal.
However, it was the C language that got extensive acceptance for, and it continues to do so. Embedded SystemThe embedded system is defined as the combination of embedded C programming software and hardware part majorly consist of microcontrollers and it is intended to perform the specific task. These types of embedded systems are being used in our daily life such as washing machines and video recorders, refrigerators and so on. The embedded system was first introduced by the 8051 microcontroller. Embedded System Introduction to the 8051 MicrocontrollerThe 8051 microcontroller is a basic microcontroller, it is first introduced by the ‘Intel Corporation’ since 1970. It is developed by the 8086 processor architecture. The 8051 is a family of the microcontroller, which has been developed by different manufactures such as Philips, atmel, dalls, and so on.
Has been used in lots of embedded products from small children’s toys to large automotive systems.
HiI am trying to get the hardware UART working on PIC16F1618 @ 8MHz, 9600bps.I have worked on hardware uart earlier with other PIC controllers. But I am not able to get this one working.when I use the UART library routines, it gives the following error:'Unresolved extern 'PPSMapping' LibUARTRemappable.c'if I use the library function: UnlockIOLOCK;to remap the pins, it gives an error again, saying, 'Undeclared identifier 'UnlockIOLOCK' in expression MyProject.c' refreing to the line where I had used this function.I have selected all libraries.So, I tried remappable UART library functions.it did not give any errors, but it did not work either.it did not receive, nor transmit anything. Data is transmitted from PC to Rx pin, but does nothing. I have checked with oscilloscopeprogram is working, not stuck, as I had put in code to toggle an output every cycle, and the output was toggling turning the LED on/OFF.I have disabled the analog function for Rx pin, set the Rx pin as input, and Tx pin as output.it does not transmit anything,cannot REMAP pins until UnlockIOLOCK; and other mapping functions work.software UART is working, but I need hardware UART for my application.thanks. First off, the power on default is for the PPS registers to be unlocked. However, the power on default for PPS1WAY is to not allow the PPSLOCK to be altered after it has been set. Therefore I strongly suggest that you leave the locking and unlocking right out of your code until you have gained experience with the device and your code - in other words this should be one of the last aspects of your code that you add.Section 12 of the data sheet is relatively straight forward once you get the hang of how the PPS works and Figure 12-1 will help you there.
In your case you want to use the Register 12-2 and Register 12-3 descriptions.You want to use the EUSART (and I assume in asynchronous mode) and so you will be interested in mapping the Tx signal to an output pin and the Rx signal to an input pin.If you look at Table 29-8, you will see a register labelled RXPPS listed. This is the register you need to set to a value to select the Rx single pin. Lets say you want this to be RA5. Looking at Register 12-2, you will see that RA5 has a value of 0b00101, so you will use. I have actually answered your question about the need to use the unlock sequence at the top of my last post.
For your device (and most Microchip MCUs from my experience) the unlock sequence is NOT required so long as you leave the power-on configuration bits in their default state. SSPCLKPPS = 0b01110; // RB6 input to SCLSSPDATPPS = 0b01100; // RB4 input to SDARB6PPS = 0b10000; // SCL output to RB6RB4PPS = 0b10001; // SDA output to RB4i missed that note earlier, thanks for pointing out.i have to write all the 4 lines????i got the point that these pins are bidirectional.what is the difference between 2 lines which i had written to 4 lines you have.??? Will it configure the same pin RB4 as input as well as output for SDA.???wont the last be over write the first line for RB4.???i might be asking some very basic questions, but i dont know anything how to use the same pin as input as well as output.and one more thing, if you can help, i have been using all built in library functions for SOFTWARE UART, I2C, SOFTWARE I2C etc., for all other peripherals., except from hardware UART.
Where should i start from if i need to write my own routines for all these.?? Is there a sample code.??Thank you for pointing out my mistakes. Yes - all 4 lines.If you look at the data sheet and the diagram at the start of the PPS section, you will see that there are 2 types of mapping: from the pin to the device for 'input' signals, and from the device to the pin for output signals. Therefore you need to set the mapping for both the input and output aspects of both pins - hence 4 lines of code.You will also see notes in that section that the peripheral also controls the TRIS lines for the selected pins so that it can handle the switching from input to output for lines such as SDA and SCK.As for writing library functions for the various peripherals, I personally think this is over rated, especially for peripherals that are as straight forward as UARTs and SPIs.
The initialisation code takes a few lines to write but is typically only executed once - and also give you a great place to put comments on what the configuration is supposed to be and why (if there are special characteristics that need to be considered). Sending and receiving values is generally very straight forward BUT the characteristics you want to use (e.g. Interrupt driven vs poling/blocking, use of circulars buffers etc.) can be very situation specific and I find library functions often hide important characteristics that mean I spend hours tracking down strange behaviors.Exceptions (for me) are TCP/IP and USB interfaces where I always use the library functions as the complexities of using these peripherals is high.Also, my experience is that library functions really do not move well from one device to another, in particular between device families.
Also, the code required for embedded applications tends to be specific to that application and you often want to get the best performance out of the limited CPU clock speed and memory - and library functions need not provide either.Susan. Adding to what Susan stated, and this is entirely a personal opinion, MikroC has lots of serial functions that do very little.Setting up something like a USART is actually very easy, there are only a few registers and it probably takes fewer lines of code to do it yourself than using the library. You also get the benefit of absolute control instead of predetermined conditions being imposed. Denon rc 1075 manual arts.
Pic Uart Interrupt Example
The key is to thoroughly read and understand the data sheets and understand how the peripheral actually works, all the information you need is there.Your particular problem with remappable pins is due to MikroC using different names to Microchip for the pins. The numbers MikroC uses are for the PIC18 devices which call them 'RPxx' in the data sheets but the PIC16 devices refer to them only by port names. Perhaps Mikro will change this in the future but for now I would code the mapping instructions by hand as Susan and I have explained.Brian.
I have written hardware UART code myself., without using library functions. I don't know how to write it for software UART, software I2C., I understand the concept for UART, but I don't understand how would you generate the output to send data.??
Would I need a timer which can generate the baud rate.??? How would I make equivalent of the timing diagram though my code.??for example, if I get high signal on one of the pins, how would I generate the CLK signal delay for milliseconds, or how would I toggle the output at such high speed to transmit ASCII and how would I store the ASCII received to make meaningful characters.??I have read online articles for software UART, but they don't clear my doubts.thank you Susan and Betwixt.I will try I2C configuration today. Doesn't mikroC has SoftI2C and SoftUART library?It probably does but in this case things are complicated by the use of remappable pins.The principle for 'bit banging' serial transmission is to use a timer to set the bit rate, at each timer tick you shift the data (rrf, rlf) and check the MSB or carry flag, copying it's state to the appropriate output pin.
You preceed the first bit with a 1-bit long start bit and at the end you add a 1-bit long stop bit.Reception is similar but you have to cater for the start bit in a special way. You monitor the input pin for the leading edge of the start bit, wait 1.5 bit lengths then sample 8 times at 1-bit length intervals.
The idea is that if you wait 1.5 bits length, the next sample will be at half way through the first data bit which is the most reliable place to test it. You repeat the sampling 8 times, rotating the pin state into a register. The serial data should then be in that register for you to use.A 'real' UART/USART does exactly the same thing but uses several samples per bit and a majority polling algorithm to improve reliability, it may also check the stop bit and parity if necessary.This is code I wrote for bit banging a serial link to a HITAG module, it's in assembly language for a 16F628A but you can see the methods I used. Doesn't mikroC has SoftI2C and SoftUART library?yes they have libraries.
BUT, I want to know the logic and steps to write my own routine for software I2C and UART. What if I have to work on some new IDE, or different microcontroller?? I will again have these doubts to ask.so better try to do this now.Thanks.-Updated -BETWIXT:thank you for the code., but I am not good at all with assembly. Still, I will try it.it will really great if you have the same code written in C.??Thanks and RegardsJaskaran Singh.
Start with the data sheet, look for timing diagrams, the ones that show lines in high, low or 'don't care' logic states. Then refer to the tables showing the rise times, fall times and bit lengths. Where you see a line driven high, you write an instruction to make the level on a pin go high, when a line is driven low, you make the pin low. If there is a time restriction you add a suitable delay.
For accepting incoming signals you do exactly the same thing only this time you use the timing to read the state of a pin. The length of the data in bits is set by using a suitable loop in your code. You can usually use a register a 'shift register' to serialize the data, you load it with the value to send and rotate it say 8 times, checking the carry bit to see if you should send a 1 or 0 in the data. For reception, you read the pin and rotate it's state into a register until it is all there then read it as normal.
It's quite easy, just follow the flow shown in the diagrams.Brian.