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I have a program in MPLAB that works correctly when sending messages through the LIN system at a baud rate of 9600, but when I change it to 19200 it does not come out. I am using the MPLAB Code configurator V4 tool and in the window for Eusart I put the 19200 which are the Baud Rates to which I want to transfer. It is expected to know the values in the eusart.c file of SP1BRGL and SP1BRGH for the Baud Rate corresponding to 19200. Tried with SP1BRGL values of 0x40,0X65,0xFE, 0x3B, 0x3D keeping SP1BRGH at 0x00. Also in the application in the Registers of the variables of Sp1BRGL and SP1BRGH so that they correspond to a Baud Rate of 19200. For the calculation, the table for pic16 was used, it is expected in high transfer speed with a 16 Mhz oscillator an SPBRG of 51 but it still did not work. I do not know what I am doing wrong, to read the data I am using a LIN analyzer tool and everything works at a Baud rate of 9600 but I take it to be 19600 for the application.

One feature of MPLAB-X which is not nearly used enough is the Simulator. It is actually very powerful and useful for testing and debugging code which will run on your board and interact with the outside world via external stimuli. There is more information on the developer help site here http://microchipdeveloper.com/mplabx:scl This is how you can use the IDE to debug your serial command line interface code using stimulus files and the UART OUTPUT window. The first trick is to enable the UART output window in the IDE. We are going to start by creating a new project using MCC which drives the UART on the PIC16F18875. Settings should look as follows: Then go on the project settings and enable the UART output window in the simulator We can now update our main code to do something simple to test the UART output. #include "mcc_generated_files/mcc.h" uint8_t buffer[64]; void main(void) { // initialize the device SYSTEM_Initialize(); INTERRUPT_GlobalInterruptEnable(); INTERRUPT_PeripheralInterruptEnable(); printf("Hello World\r\n"); If you run this code in the simulator it will open an additional output window which will show the output from the UART as follows Now the next trick is to use a stimulus file to send your test data into the device via the UART to allow you to test your serial processing code. First we will make a test file, there is more information on the format of these files on the developer help site, but it is fairly easy to understand just by looking at the example. // Start off by sending 0x00 00 // First string, send the bytes H E L L O (no \0 will be sent) "HELLO" // Wait for 100 ms before sending the next bit wait 100 ms // Second string " WORLD" // Wait for 100 ms before sending the next bit wait 100 ms // Send an entirely binary packet 90 03 00 14 55 12 We now simply save this text file so that we can import it into the stimulus system. We will just call it data.txt for now. Next we have to set up the IDE to send the data in this file. We are going to start by opening the Stimulus editor, this is under the menu "Window | Simulator | Stimulus" in MPLAB-X. Navigate to the tab labeled "Register Injection" and do the following steps: To add the file we will enter a new row here. Just type in the empty boxes (or you can use the icons on the left to add a new row) Provide any label (we are using TEST) Select the UART1 Receive Register under Reg/Var - it is called RC1REG Choose "Message" for the trigger Click on the filename block to select the file we made above Set "Wrap" to no - this means it will not repeat Format should show Pkt and be raed-only The stimulus is now set up and ready for a test drive. As a test we are just going to update the program to echo back what it receives and we will be able to see the output in the Simulator Output window as the stimulus is being sent in. Here is the test code: #include <stdint.h> #include "mcc_generated_files/mcc.h" void main(void) { // initialize the device SYSTEM_Initialize(); INTERRUPT_GlobalInterruptEnable(); INTERRUPT_PeripheralInterruptEnable(); printf("Hello World\r\n"); while (1) { EUSART_Write(EUSART_Read()); } } If you now run the simulator the UART output will just show "Hello World" as the start message. When you hit the green run button on the stimulus it will send the data in the file to the program. Hitting the run button a second time will remove the stimulus and if you hit it one more time it will apply the stimulus a second time. That is a very basic introduction of how to use a stimulus which feeds data from a text file into the UART for testing purposes. It is a small step from here to feed data into a variable or into a different peripheral, we will not go into that right here, but know that it is easy to also do this. When you combine this feature with running MDB from the command line and using a test framework such as Unity http://www.throwtheswitch.org/unity/ you should have all the tools to create automated tests for your serial port code. As always the project with the code we used is attached. SimulatorUART.zip

Hello All, I am working on a project (in MPLAB v5.10) with a PIC18F27K40 (PIC18 library v1.77.0) and I'm using the MCC (v3.85.1) generated I2C drivers, I2CSIMPLE from the Foundation Services. I can read from and write successfully to devices on the I2C bus. The problem comes when I try to communicate with a device that's not on the bus, the micro goes into an endless loop waiting for i2c_status to not be busy. My knowledge of programming in C is about 6 on a scale of 10, and for programming for embedded purposes, about 5 out of 10. I would like to have it so that I can check if a specific device is present on the I2C bus, and also be able to recover from errors on the bus without it going into a loop indefinitely. This I2C driver is pretty complex, and I am having difficulties wrapping my head around it. How would I make it so that the driver just returns an error or something I can check for status, rather than loop endlessly until the operation completes, which it never will? I have not edited any of the MCC generated code. This includes leaving the IRQ enable line commented in the i2c_master.c file, so instead it polls instead of using an interrupt to check if the i2c operation has completed. // uncomment the IRQ enable for an interrupt driven driver. // mssp1_enableIRQ(); Following is an example of how I am calling the i2c driver. i2c_write1ByteRegister(address, 0x0D, 0x07); // GPPUB pull-ups on pins 0-2 I am attempting to initialize a port extender, MCP23018, specifically enabling some pull-up resistors. I would like to issue this command, and if the extender is not present, then the micro will perform some tasks differently. With the port extender present the write operation works as expected and everything is fine. Of course the problem is when the extender is NOT on the bus to acknowledge. I have another question as well. This driver seems to operate a little slow. When watching the bus with a logic analyzer I noticed a rather long pause between bytes. I went looking through the i2c driver and in i2c1_driver.c I found the following code which I suspect is the cause. inline void mssp1_waitForEvent(uint16_t *timeout) { // uint16_t to = (timeout!=NULL)?*timeout:100; // to <<= 8; if(PIR3bits.SSP1IF == 0) { while(1)// to--) { if(PIR3bits.SSP1IF) break; __delay_us(100); } } } What is the purpose of the 100 us delay in the while loop? Reducing or eliminating the delay results in reducing or removing the pause between byte transactions, but I don't know enough to know how else this edit will effect the driver. Also, what is the commented out code at the top of the function used for? Is this part of the infinite loop problem I mentioned above? -- James Burkart

I decided to write this up as bootloaders have pretty much become ubiquitous for 32-bit projects, yet I was unable to find any good information on the web about how to use linker scripts with XC32 and MPLAB-X. When you need to control where the linker will place what part of your code, you need to create a linker script which will instruct the linker where to place each section of the program. Before we get started you should download the MPLAB XC32 C/C++ Linker and Utilities Users Guide. There is also some useful information in the MPLAB XC32 C/C++ Compiler User’s Guide for PIC32M MCUs, the appropriate version for your compiler should be in the XC32 installation folder under "docs". This business of linker scripts is quite different from processor to processor. I have recently been working quite a bit with the PIC32MZ2048EFM100, so I will target this to this device using the latest XC32 V2.15. This post will focus on what you need to to do to get the tools to use your linker script. Since XC32 is basically a variant of the GNU C compiler you can find a lot of information on the web about how to write linker scripts, here is a couple. http://www.scoberlin.de/content/media/http/informatik/gcc_docs/ld_3.html https://sourceware.org/binutils/docs-2.17/ld/Scripts.html#Scripts Adding a linker script The default linker script for the PIC32MZ2048EFM100 can be found in the compiler folder at /xc32/v2.15/pic32mx/lib/proc/32MZ2048EFM100/p32MZ2048EFM100.ld. If you need a starting point that would be a good place. For MPLAB-X and XC32 the extention of the linker script does not have any meaning. The linker script itself is not compiled, it is passed into the linker at the final step of building your program. The command line should look something like this for a simple program: "/Applications/microchip/xc32/v2.15/bin/xc32-gcc" -mprocessor=32MZ2048EFM100 -o dist/default/production/mine.X.production.elf build/default/production/main.o -DXPRJ_default=default -legacy-libc -Wl,--defsym=__MPLAB_BUILD=1,--script="myscript.ld",--no-code-in-dinit,--no-dinit-in-serial-mem,-Map="dist/default/production/mine.X.production.map",--memorysummary,dist/default/production/memoryfile.xml" The linker script should be listed on the command line as "--script="name" When you create a new project MPLAB will create a couple of "Logical Fodlers" for you. These folders are not actual folders on your file system, but files in these are sometimes treated differently, and Linker Files is a particular case of this. My best advice is not to ever rename of in any other way mess with these folders created for you by MPLAB. If you did edit configurations.xml or renamed any of these I suggest you just create new project file as there are so many ways this could go wrong fixing it will probably take you longer than just re-creating it. I have seen cases where it all looks 100% but the IDE simply does not use the linker script, just ignoring it. The normal way to add files to a MPLAB-X project is to right-click on the Logical folder you wanted the file to appear in and select which kind of file under the "New" menu. In this menu files that you use often are shown as a shortcut, to see the entire list of possible files you need to select "Other..." at the bottom of the list. Unfortunatley Microchip has not placed "Linker Script" in this list, so there is no way to discover using the IDE how to add a linker script. When it all goes according to plan (the happy path) you can simply right-click on "Linker Files" and add your script. This is also what the manual says to do of course. When you have added the file it should look like this (pay careful attention to the icon of the linker script file, it should NOT have a source code icon. It should just be a white block like this, and if this is the case the program should compile just fine using the linker script, you can confirm that the script is being passed in by inspecting the linker command line. Adding a linker script - Problems - when it all goes wrong! I noticed in the IDE that the icon for the script was actually that of a .C source file. When this happens something has gone very wrong, and the compiler will attempt to compiler your linker script as a C source file. You will end up getting an error similar to this, stating that there is "No rule to make target": CLEAN SUCCESSFUL (total time: 51ms) make -f nbproject/Makefile-default.mk SUBPROJECTS= .build-conf make[2]: *** No rule to make target 'build/default/production/newfile.o', needed by 'dist/default/production/aaa.X.production.hex'. Stop. make[1]: Entering directory '/Users/cobusve/MPLABXProjects/aaa.X' make[2]: *** Waiting for unfinished jobs.... make -f nbproject/Makefile-default.mk dist/default/production/aaa.X.production.hex make[2]: Entering directory '/Users/cobusve/MPLABXProjects/aaa.X' make[1]: *** [.build-conf] Error 2 "/Applications/microchip/xc32/v2.15/bin/xc32-gcc" -g -x c -c -mprocessor=32MZ2048EFM100 -MMD -MF build/default/production/main.o.d -o build/default/production/main.o main.c -DXPRJ_default=default -legacy-libc make: *** [.build-impl] Error 2 make[2]: Leaving directory '/Users/cobusve/MPLABXProjects/aaa.X' nbproject/Makefile-default.mk:90: recipe for target '.build-conf' failed make[1]: Leaving directory '/Users/cobusve/MPLABXProjects/aaa.X' nbproject/Makefile-impl.mk:39: recipe for target '.build-impl' failed BUILD FAILED (exit value 2, total time: 314ms) I tried jumping through every hoop here, even did the hokey pokey but nothing would work to get the IDE to accept my linker script! I even posted a question on the forum here and got no help. At first I thought I would be clever and remove the script I just added, and just re-add it to the project, but no luck there. So now I was following the instructions exactly, my project was building without the script, I right-clicked on "Linker Files" selected "Add Existing Item" and then selected my script and once again it showed up as a source file and caused the project build to fail by trying to compile this as C code 😞 Next attempt was to remove the file, then close the IDE. Open the IDE, build the project and then after this add the existing file. Nope, still does not work 😞 I know MPLAB-X from time to time will cache information and you can get rid of this by deleting everything from the project except for your source files, Makefile and configurations.xml and project.xml. I went ahead and deleted all these files, restarted the IDE, added the file again - nope - still does not work. So much for RTFM! Eventually our of desperation I tried to rename the file before adding it back in. Even this did not work until I got lucky - I changed the extention of the file to gld (a commonly used extension for gnu linker files), and tried to re-add the file, and this eventually worked ! If you are having a hard time getting MPLAB-X to add your linker script, do not dispair. You are probably not doing anywthing wrong! The right way to add a linker script to your project is indeed to just add it to "Linker Files" as they say, sometimes you just get unlucky due to some exotic bugs in the IDE. Just remove the file from your project, change the extention to something else (it seems like you can choose anything as long as it is different) and add the file back in and it should work. If not come back here and let me know and we can figure it out together :)

I am trying to use a linker script with MPLAB-X for my PIC32 project but for some reason the script is not being passed to the linker at all. I expected that all I had to do was add the .ld file to my project, typically by placing it in the "Linker Files" virtual folder in MPLAB-X in my project. I did this and the linker script is being ignored by the linker. This is one of those $100 questions (if you know the story of the mechanic asking $100 for knowing where to hit ...). So my question is how do I get MPLAB-X to use my linker script which I have added to the PIC32 project?