Faking an RS2. 32 Serial Port. Another alternative, even though the OP did not ask for it There exist usb to serial adapters. Depending on the type of adapter, you may also need a nullmodem cable, too. They are extremely easy to use under linux, work under windows, too, if you have got working drivers installed. That way you can work directly with the sensors, and you do not have to try and emulate data. That way you are maybe even save from building an anemic system. Due to your emulated data inputs not covering all cases, leading you to a brittle system. Its often better to work with the real stuff. 267 Replies to Android USB Host Arduino How to communicate without rooting your Android Tablet or Phone. The Raspberry Pi as a Stratum1 NTP Server. As an experiment, I purchased one of the lowcost creditcardsize Raspberry Pi computers, and have configured it to run. How to communicate without rooting your Android Tablet or Phone Using Android in Industrial Automation. Intro. In the past two posts we have explained the basics of USB communication with the Arduino Uno also applicable for Arduino Mega. Galaxy Nexus to Arduino UNO via USBIn this post well put everything together and show you how to communicate between your Android application and the Arduino using nothing but the Android USB host API. Remember, this approach has nothing to do with Android ADKUnlike Android ADK, your Android device will act as the USB host, while your Arduino board will act as the USB device. For the following application to work, you will require an Android device that supports USB host mode as well as the USB host API. Most Android 3. 1 tablets will suffice some may require an USB OTG adapter. Also, the Galaxy Nexus has host mode enabled and matches the requirements you will need an USB OTG adapter however. This example consists of two parts The Android application that makes use of the USB APIA simple Android app that lets you regulate the brightness of an LED on the Arduino using a slider. It also features a button to enumerate the USB device. Firmware for the Arduino that does some serial IO with the Android app. Very basic firmware for the Arduino. An interrupt is generated when a new byte is received. The received data controls the brightness of the Arduinos on board LED. implemented via usleep style software pwm in the main loop. The Arduino firmware. In the main loop the firmware asserts and clears the LED pin of the Arduino PB5. Here is a shortened excerpt. PORTB 1 lt lt LED. PORTB 1 lt lt LED. During a period of 2. LED is asserted for a duration of pause1. Simply put, this is a very simple software PWM. During that time, data and consequently pause may be changed within an interrupt routine form the serial USART port. This happens when the Android side sends data to the Arduino. The interrupt routine is extremely basic. ISRUSARTRXvect attention to the name and argument here, wont work otherwise. UDR0 UDR0 needs to be read. The RX data has to be read in the ISR interrupt service routine from UDR0 have a look at the Atmega. P reference manual for further details. Since we are doing no multi buffering shenanigans the handling is extremely simple no need to call cli or anything. The rest of the code is initialization of the IO pins and UART functionality. Download the complete example here ledpwm. Controlled LED on the UNO by the firmware. The Android app. The Android application uses the basic knowledge of the preceding blog post Arduino USB transfers. During USB initialization, the Arduino USB serial converter is set up and after that, communication is done using the bulk IN endpoint of the very same serial converter. With both the aforementioned firmware installed your Arduino board and the Android application installed on your phone or tablet, you will be able to control the brightness of the Arduino Unos built in LED with a slider on your Android device. Again, please note that this will only work with devices that actually support both USB host mode hardware, kernel requirement as well as the Android USB host API Android OS requirement. The source code is available here Usb. Controller. tar. gz You may need to change the PID value in Usb. Controller. Activity. Arduino Uno Rev. 3 or higher. You can check the VIDPID value with lsusb after connecting the Arduino to your computer. Many parts of the code are probably familiar to Android SW engineers. The most interesting section is in the class Usb. Controller where the Arduino device is set up and communication is initiated. So lets have a closer look at the inner class Usb. Runnable within Usb. Controller. private class Usb. Runnable implements Runnable. Usb. Device m. Device. Usb. RunnableUsb. Device dev. m. Device dev. public void run here the main USB functionality is implemented. Usb. Device. Connection conn m. Usb. Manager. open. Devicem. Device. Interfacem. Device. Interface1, true. Arduino USB serial converter setup. Transfer0x. 21, 3. Transfer0x. 21, 3. Usb. Endpoint ep. IN null. Usb. Endpoint ep. OUT null. Usb. Interface usb. If m. Device. get. Interface1. for int i 0 i lt usb. If. get. Endpoint. Count i. if usb. If. get. Endpointi. Type Usb. Constants. USBENDPOINTXFERBULK. If. get. Endpointi. Direction Usb. Constants. USBDIRIN. IN usb. If. get. Endpointi. ep. OUT usb. If. get. Endpointi. Send. Lock ok there should be a OUT queue, no guarantee that the byte is sent actually. Send. Lock. wait. Interrupted. Exception e. Stop. m. Connection. Handler. on. Usb. Stopped. e. print. Stack. Trace. conn. Transferep. OUT, new byte m. Data, 1, 0. if m. Stop. m. Connection. Handler. on. Usb. Stopped. After the USB interface has been claimed the Arduino USB serial converter is initialized by issuing the following control transfers. Transfer0x. 21, 3. Transfer0x. 21, 3. The first call sets the control line state, the second call sets the line encoding 9. N1. For communication, an additional thread is used to send data without blocking the Activitys main UI thread. By notifying s. Send. Lock of the Usb. Controller the data will be transferred. After submission, the thread will go into wait again. This way, even if submission takes more time than expected, the Activitys main thread will not be blocked and hence the app will not become unresponsive. Screenshot of the Android App. Also note that in the Android Manifest none of the XML style device filters are needed, since enumeration happens by the user in the app when pressing the enumerate button. Device filters and therefore automatic activity launch when connecting the Arduino are not used in this example in order to make the code simpler to comprehend. However, this could be easily implemented with a few lines of additional code. For developing this example we have used a Galaxy Nexus Phone with an USB OTG adapter cable. It has also been successfully tested with an Android Tablet, the Acer Iconia Tab A5. This post concludes the 3 Part Arduino USB communication series. Feel free to post any questions or feedbackideas in the comments section or contact us via E Mail http www. All code you find in this post can be used under GPL for your own projects. The following section About Android and USB Host again concludes why USB Host is becoming more and more important for mobile devices and points out main differences between Android ADK Android Accessory Development Kit and the Android USB Host API. EDIT control transfers for FTDI equiped Arduinos. Since we got requested a lot if the FTDI Usb Serial converter will work too, here ist the control transfer code that needs to be exchanged. No warranties though. Transfer0x. 40, 0, 0, 0, null, 0, 0 reset. Transfer0x. 40, 0, 1, 0, null, 0, 0 clear Rx. Transfer0x. 40, 0, 2, 0, null, 0, 0 clear Tx. Transfer0x. 40, 0x. Source Links. Android App Usb. Controller. tar. gzrduino main ledpwm. You may need to change the PID value in Usb. Controller. Activity. Arduino Uno Rev. 3 or higher. You can check the VIDPID value with lsusb after connecting the Arduino to your computer. About Android and USB Host. Lately it has become more and more popular to use tablets or mobile phones to communicate with the outside world over USB.