AVR ATtiny USB Tutorial Part 4 Code and Life. All right. Now that we got the basic USB code working in part 3, its time to wrap things up in this tutorial series. This fourth section will explain how to send data from your device to PC and also the other way around. I may later do a fifth part on how to make a USB HID device like a keyboard or mouse, so if you havent already, Id recommend subscribing to the RSS feed to get updates. Sending data from device to PCIf you look carefully at our command line client code, you probably noticed that the control messages sent to toggle the led are of type USBENDPOINTIN and we have a 2. So far we have not received any data and the return value stored in n. Bytes has been zero. Lets change that. If you read through the documentation in usbdrvusbdrv. Function. Setup we used to toggle our LED on device side, you can see that there are two ways to return data from usb. Function. Setup Set the global pointer usb. Msg. Ptr to a static RAM memory block and return the length of data from the function. Define usb. Function. Read function to do it yourself. We will be using the first method. First we define an additional message USBDATAOUT and a static buffer to store the data we want to send from device to PC. The bicycle rental database below is a work in progress that will grow over time with your help. Most of the list below was originally provided in a pamphlet by the. XP mode, i think we will just leave it like that, there is some talk of converting this into a Excel or access sheet, currently he is the. Hot Tamales are a simple candy, theyre just cinnamon flavored jelly beans, in a long rod shape. Cinnamon candies arent always easy to find, so its nice that. Readers of this article should also read Fake driving licenses a shocker Pssssst, hey buddy Wanna buy a drivers license Have you received one of these in the. Piedra Turmalina Negra Donde Comprar Viagra discount. Office Depot OfficeMax is a onestop shop for all your candy needs. Shop online or instore today for great deals on wholesale candy more. Test your knowledge with amazing and interesting facts, trivia, quizzes, and brain teaser games on MentalFloss. Arcor Talk Show' title='Arcor Talk Show' />USBDATAOUT 2. Buf1. 6 Hello, USB. Then we add a new case to usb. Die erste weltweite flashmobDatenbank mit allen wichtigen Terminen. Function. Setup to return the contents of that buffer. USBDATAOUT send data to PC. Msg. Ptr reply. Buf. Buf. Whoa, that was easy V USB does all the rest for us. Now the only thing needed to do is to update our command line client to include our new out command. Copy the define from above to the beginning of usbtest. Bytes usbcontrolmsghandle. USBTYPEVENDOR USBRECIPDEVICE USBENDPOINTIN. USBDATAOUT, 0, 0, char buffer, sizeofbuffer, 5. Got d bytes sn, n. Bytes, buffer. Just run make and make flash to compile and update the firmware. Now try usbtest out how easy was that With 1. RAM on ATtiny and V USB using a lot of that, you will not be able to transmit the maximum of 2. Function. Read to transfer longer buffers piece by piece, but even 1. And of course you can chain multiple control requests if you want to receive more data. Sending data from PC to device. If you only need to send a few bytes of additional data, you can use the w. Value and w. Index parameters for that. Lets make a new USBDATAWRITE that changes the USB part of our return message to any four characters. First a new define add to both main. USBDATAWRITE 3. Then a new case to firmware side. USBDATAWRITE modify reply buffer. Buf7 rq w. Value. Buf8 rq w. Value. Buf9 rq w. Index. Buf1. 0 rq w. Index. Note that the w. Value and w. Index are actually unions that allow you to either access the whole 1. Value. word or alternatively directly access the lower and upper bytes with w. Value. bytes0 and w. Value. bytes1, respectively Im not sure if the order of upper and lower bytes in the word depends on endiandness on PC side, but thats how it works for me. On command line side, we add another else if that sends fixed letters for simplicity. Bytes usbcontrolmsghandle. USBTYPEVENDOR USBRECIPDEVICE USBENDPOINTIN. USBDATAWRITE, T E lt lt 8, S T lt lt 8. Just compile with make, update firmware with make flash and try out the new usbtest write command. Note that the command itself does not print anything, you need to run usbtest out before and after to see how the buffer is changed. Also note that until you reset or unplug the device, the new message Hello, TEST will stay in the device. Sending more data to the device. Using w. Value and w. Index is fine for many applications, but if wed like to update the whole 1. Lets now create our first USBENDPOINTOUT message. On PC side the code is pretty simple. USBDATAIN 4. else ifstrcmpargv1, in 0 argc 2. Bytes usbcontrolmsghandle. USBTYPEVENDOR USBRECIPDEVICE USBENDPOINTOUT. USBDATAIN, 0, 0, argv2, strlenargv21, 5. Note that the buffer size is one more than just the argument 2 length to accommodate the string terminating NULL character. On device side we add a new variable to keep track how many bytes we are to read, and use a special return value from usb. Function. Setup this is all well documented in usbdrv. USBDATAIN 4. static uchar data. Received 0, data. Length 0 for USBDATAIN. USBDATAIN receive data from PC. Length ucharrq w. Length. word. data. Received 0. ifdata. Length sizeofreply. Buf limit to buffer size. Length sizeofreply. Buf. return USBNOMSG usb. Function. Write will be called now. Now that the request is of type control out USBENDPOINTOUT on PC side code and we have returned USBNOMSG with byte size return value its actually 2. V USB will call a function named usb. Function. Write to receive the data sent. USBPUBLIC uchar usb. Function. Writeuchar ata, uchar len. Received lt data. Length i lt len i, data. Received. reply. Bufdata. Received datai. Received data. Length 1 if we received it all, 0 if not. Last thing to do is to modify usbconfig. V USB we have provided such a function. USBCFGIMPLEMENTFNWRITE 1. Now you should be able to remake and flash the project and use the new usbtest in abcdefgh command to replace the values in devices 1. Note that if you supply a string longer than 1. NULL character will not fit into buffer and usbtest out may print out garbage after the 1. This is just a demo application so we ignore that for now. Final remarks. Congratulations You have successfully built and coded a USB device that is able to receive commands and sendreceive arbitary data. Once you have understood how V USB calls usb. Function. Write, it should also be pretty straightforward to make usb. Function. Read in similar manner to send longer data to PC in multiple parts. I have compiled the Makefile and source code files as well as relevant portions of V USB and libusb win. Update If you dont for some reason like the command line usbtest. Gnter Meinel has created an excellent GUI version of the test program using Borland C Builder 3. You can get it with source code from here http home. I hope you have enjoyed the tutorial, and hope to see you again on this site, Im planning to write at least a bit about 7 segment LED multiplexing, driving LCDs directly with AVR, and Pico. Windows 7 Ultimate Genuine Activation Patch. Scope USB oscilloscope in the future, and may add new subjects as I get further myself. This is the end of the main arc of my V USB tutorial, but I recommend you to read my later posts in the V USB tutorial series, including.