Pic c serial

You can either create a simple assembler file with the following sort of code:. Note: It is not worth trying to code the value into the C source as it will use a non-standard method of programming. Alternatively download winpic look online to download it and set the device to 12F, load up the hex file and go to the memory location in winpic and type in the last location the value 34 followed by the CAL value you have previously stored.

Save the file. You can check it worked by re-building the original hex file so the manually inserted CAL value is lost. Re-program this new hex into the PIC.

Then upload the hex data. View memory as above and scroll to bottom - the new CAL value will be there. Only the upper six bits are used as the calibration bits so values must be different by 4 to change to the next OSCCAL setting e. Microchip calibrates the 12F microcontroller and places a calibration value at address 0x3FF. You have to write and use a routine to set the register OSCAL with the stored value : It is not done automatically for you! Note: You have to use the following assembler code: The code the data sheet suggests you use to set the calibration value into the OSCCAL register is :.

All this does is call the location that contains the RETLW value which then returns the calibration value. Note: If the value stored at location 0x3ff is zero the oscillator may not work so -don't call this function if the CAL value is corrupted. Use a frequency counter to measure the output you can find a project on this site here. The first byte of the instruction is 0x34 and the second is the value returned so for a calibration value of 0x20 you would put: 0x at address 0x3FF Re-program the chip.

Note: See the tip for storing the calibration value so you will never forget it or loose it again. Read more. One common problem: Programming a sketch into the chip without a reset control - solved here. How Arduino strtok works, and how to use it and how to avoid problems. How to use Arduino if else statements to make decisions in your programs. Frames of information must not necessarily be transmitted at equal time space, since they are independent of the clock.

This component can be configured as:. To enable the serial communication with PIC micro we must set different parameters within two registers: click the links for the explanation of each bit.

This information will be stored inside TXREG register, which acts as a temporary buffer storage of information prior to transmission. Transmitting 8 bit data. The received information will be stored in the RSR register, which acts as a temporary buffer storage.

Receiving 8 bit data. Suppose we want to transmit the following information: This information is in the size of 9-bit, so there is not enough space to store all the information in the TXREG register. It is important to note, that first we need to store the 9th bit and only later other 8-bits. This is important because the information of 8 bits may be transmitted immediately once being inside the TXREG register. As a result the transmitted information will be incorrect.

Transmitting 9 bit data. The received, lower 8-bit information, will be stored in the RSR register, which acts as a temporary buffer storage. Receiving 9 bit data. Each transmission is transmitted in the particular rate BAUD.

The baud rate is measured in units of bps bit per second or kbps kilo bit per second. This is done by setting the system clock to the value needed. As discussed previously, in asynchronous mode, the baud rate of transmission of the information can be set to high speed or to low speed. The following outlines how the value which is placed in the SPBRG register is being computed, in the case of a high baud rate and low baud rate. USART transmit block diagram. This is done by setting the CREN bit.

You can easily use those functions within your code. If you have some issues doing so, you can always refer to the previous tutorial using the link below. And if you also find troubles creating this file, you can always refer to the previous tutorial using the link below. Now, open the main. Our task is to take 3 inputs from the user using 3 push buttons to do the following tasks:.

Button1: increment the data value. Button2: decrement the data value. Button3: send the current data frame via UART bps.

Here is the full code listing for the transmitter MCU chip. And here is the full code listing for the receiver MCU chip. Create the simulation project on your simulator and connect your circuitry as shown in the schematic diagram down below.

Add the hex code to the respective microcontroller chip. The receiver code to the receiver chip and so. Click the run button and test out everything! The Running Simulation Test! The previous code listings for this lab despite being fully-functional.

It may need a little bit of work to get it working at a different baud rate or at a different clock frequency. The received data will be a total mess garbage!

So try to generate the exact same baud rate at both ends to avoid mismatching error. Communication channels can go crazy in almost any system.

Device A: is programmed to send a data frame of 0x Yet, device B is printing out some random garbage! The question is, who is the criminal to suspect?

What I prefer, is to use one of the following methods. I assume that everybody should be familiar with capturing signals on a generic CRO or a Logic analyzer.

Using it will make your life much more easier, but why? Use your own tools and what you personally prefer for debugging. And determine where and which changes have to be made! UART serial buses can go for quite long distances if your application needs so. However, the maximum allowed baud rate gets limited as you go further respectively.

The maximum cable length for RS is 50ft. But in practice, it depends on the baud rate, cable specific capacitance, and ambient noise. The table below contains some rules-of-thumb from experiments done by Texas Instruments years ago. Hence, you have to figure out the following 3 things. The longer the cable and higher the resistance, the more the voltage change is detected at one end compared to the other. The higher the capacitance of wires, the slower its state changes and more rounded-off the signal becomes.

Therefore, the higher the speed and longer the distance, the signal will start to look less like a square wave and more like a noisy sine wave. And due to the low voltage swing and without differential signaling, it gets harder to communicate farther. However, twisted-pair cables with shielding will greatly help. As well as the RS An overrun error occurs when the receiver cannot process the data frame that has just arrived in the buffer before the next one arrives. Various devices have different amounts of buffer space to hold received data.

The word in the RSR the 3rd byte will be lost. Overrun bit OERR has to be cleared in software. This is done by resetting the receive logic CREN is cleared and then set. It is, therefore, essential to clear error bit OERR if it is set. As the start bit is used to identify the beginning of an incoming data frame, its timing is a reference for the remaining bits. Which means the timing between data bits, start bit, and stop bit is somehow for whatever reason is just messed up!

A break condition on the line is also signaled as a framing error. There exist many reasons for which a framing error may occur such as:.

Bit FERR and the 9th receive bit are buffered the same way as the receive data. This happens when you attempt to connect more than 2 devices on the UART serial bus. Which will at least cause data corruption at the receiving end. Hence, connecting any additional serial device e. Bluetooth Module, GPS, etc. Eventually, they tend to use software emulated serial UART instead.

Due to the Bus Contention Error. There is always fundamental limitations and drawbacks for what software can emulate. Just in case your demand for a UART is moderately low. But if your application needs extensive UART communication, then you should look for a hardware solution.

As overloading your CPU with unnecessarily expensive in time software will be a totally inefficient way to go. It took me several days to craft this resource on that topic.

And most of the information here represents my knowledge and point of view which may have some pitfalls. Just for the sake of consistency in firmware implementations using these MCU chips. To keep the theoretical side more relevant to practice, I had to do so. However, I just wanted to disclaim it for you. I love reading, writing, creating projects and Technical training.

A reader by day a writer by night, it's my lifestyle. You can view my profile or follow me via contacts. July 1, June 2, October 2, Hello sir, Its my earliest request to you that please provide ADC tutorial in deep covering every aspects of it. Sorry for the delay. A notification will be sent automatically to all subscribers. I found your tutorial to be really fascinating and well documented. Thank you so much for this hard work.

Please keep it coming on other communication protocols as well. As for Hitech-c, I think it should also work with no problems. Thank you so much Sir for better explanation of the above tutorial. But for now, you can check nandland. I have a problem related to UART. UART tutorial needs a little corrections. Thanks a lot! I really appreciate your contribution. I remember you have stated that RCIF bit can only be clared by hardware. Then why did you clear this bit by writing 0 to it?

Generally, interrupt flag bits have to be cleared in software after servicing the interrupt request inside the isr. Check it out and tell me what you will get! These lines are from receiver firmware. Were these lines necessary? On the on the other hand, the init fubction can not be defined without declaring it at the bedinning. The declaration is still important. Unless you move the function definition block to be above the main. In this case, no declaration is needed.

Thanks Khaled for such in depth tutorials. I am using them together with PIC micro-controller datasheet and I always come right. One question though, what is difference between computer science and computer engineering? My code fails because I do not understand how to read a string rather than a single character. I expect I need to disable interrupts and reset pointers etc, but an example of receiving strings using the ISR would be very helpful.

Awesome Tutorial. I have come across a very long way to this. So far best Tutorial. UART explained very elaborately. OR another tutorial may be :. Thank you. Hi Kareem! Nice question. You can also google this subject to get an idea how reading a uart bit 16 times is useful. It helps uart module to make sure that a specific received bit is a 0 or 1. Greatings Khaled.