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USBHostSerial
Mbed OS 2 and Mbed OS 5
This is the handbook for Mbed OS 2. If you’re working with Mbed OS 5, please see the Mbed OS 5 documentation.
The USBHostSerial interface is used to communicate with a virtual serial port usb device.
Library in Beta!
This library is in Beta. If you have any problems using the USBHost library, please send a bug report at support@mbed.org
The USB Host connector should be attached to
- p31 (D+), p32 (D-) and GND for the LPC1768
- add two 15k resistors tied to GND on D+ and D-
Hello World¶
Import program
00001 #include "mbed.h" 00002 #include "USBHostSerial.h" 00003 00004 DigitalOut led(LED1); 00005 Serial pc(USBTX, USBRX); 00006 00007 void serial_task(void const*) { 00008 USBHostSerial serial; 00009 00010 while(1) { 00011 00012 // try to connect a serial device 00013 while(!serial.connect()) 00014 Thread::wait(500); 00015 00016 // in a loop, print all characters received 00017 // if the device is disconnected, we try to connect it again 00018 while (1) { 00019 00020 // if device disconnected, try to connect it again 00021 if (!serial.connected()) 00022 break; 00023 00024 // print characters received 00025 while (serial.available()) { 00026 printf("%c", serial.getc()); 00027 } 00028 00029 Thread::wait(50); 00030 } 00031 } 00032 } 00033 00034 int main() { 00035 Thread serialTask(serial_task, NULL, osPriorityNormal, 256 * 4); 00036 while(1) { 00037 led=!led; 00038 Thread::wait(500); 00039 } 00040 }
API¶
Import libraryUSBHost
Troobleshooting
If your mbed board is automatically resetted when you plug a USB device, you should consider to use an external power supply