Update README

README.md

@@ -10,7 +10,7 @@ This software is licenced under the GPL v2 and is intended for amateur and educa
 
 - Supported modes: D-Star, DMR, Yaesu Fusion, P25 Phase 1 and NXDN
 - Automatic mode detection (scanning)
-- G4KLX software suite: [MMDVMHost](https://github.com/g4klx/MMDVMHost), [ircDDBGateway](https://github.com/dl5di/OpenDV), [YSFGateway](https://github.com/g4klx/YSFClients), [P25Gateway](https://github.com/g4klx/P25Clients), [DMRGateway](https://github.com/g4klx/DMRGateway) and [MMDVMCal](https://github.com/g4klx/MMDVMCal)
+- G4KLX software suite: [MMDVMHost](https://github.com/g4klx/MMDVMHost), [ircDDBGateway](https://github.com/dl5di/OpenDV), [YSFGateway](https://github.com/g4klx/YSFClients), [P25Gateway](https://github.com/g4klx/P25Clients), [DMRGateway](https://github.com/g4klx/DMRGateway), [NXDNGateway](https://github.com/g4klx/NXDNClients) and [MMDVMCal](https://github.com/g4klx/MMDVMCal)
 - Bands: 144, 220, 430 and 900 MHz (VHF requires external inductor)
 - Status LEDs (PTT, COR and digital modes)
 - Serial repeater port for Nextion displays
@@ -35,6 +35,8 @@ Dual ADF7021 for full duplex operation (#define DUPLEX in Config.h) will work on
 
 If you can't decode any 4FSK modulation (DMR, YSF, P25 or NXDN) with your ZUMspot, the common solution is to adjust RX frequency offset (RXOffset) in your MMDVM.ini file. Please try with steps of +-100 Hz until you get low BER. If you don't have test equipment, the procedure is trial and error. In some cases TXOffset adjustment is also required for proper radio decoding. If you have test equipment, please use [MMDVMCal](https://github.com/g4klx/MMDVMCal).
 
+If you have problems updating firmware using USB bootloader (DFU mode) on Orange Pi or any other system different from RPi, you could compile the dfu tool directly. You could get the source code of a dfu tool [here](https://sourceforge.net/projects/dfu-programmer/files/dfu-programmer/0.7.0/).
+
 # Quick start
 
 Please see [BUILD.md](BUILD.md) for more details, and also [MMDVM](https://groups.yahoo.com/neo/groups/mmdvm/info) Yahoo Groups. You also can check at MMDVM_HS/scripts folder for some automatic tasks.