Fix consistent fuse settings with Arduino burn bootloader.

QCX-SSB.ino

@@ -62,7 +62,7 @@ experimentally: #define AUTO_ADC_BIAS 1
 #include <avr/sleep.h>
 #include <avr/wdt.h>
 
-//FUSES = { .low = 0xF7, .high = 0xD1, .extended = 0xFD };   // Fuse settings should be E=FD H=D1 L=F7, at programming.
+//FUSES = { .low = 0xFF, .high = 0xDE, .extended = 0xFD };   // Fuse settings should be E=FD H=D1 L=F7, at programming.
 
 class LCD : public Print {  // inspired by: http://www.technoblogy.com/show?2BET
 public:  // LCD1602 display in 4-bit mode, RS is pull-up and kept low when idle to prevent potential display RFI via RS line

README.md

@@ -155,7 +155,7 @@ The following performance measurements were made with QCX-SSB R1.01, a modified
 
 ### Notes:
 1. <a name="note1"/>Firmware upload variations:
-- [AVRDudess] tool or avrdude CLI (avrdude -c avrisp -b 19200 -P /dev/ttyACM0 (or: /dev/ttyUSB0) -p m328p -e -U efuse:w:0xfd:m -U hfuse:w:0xC1:m -U lfuse:w:0xF7:m -U flash:w:firmware.hex) can be used for uploading the firmware via the ISP connector on the QCX. Follow [Arduino as ISP] instructions if you have a Arduino UNO board available (tip: use female-to-male breadboard cables to connect Arduino to QCX ISP jumper); or [USBasp] instructions if you have a USBasp programmer, alternatively use [USPasp ExtremeBurner]; but many other ISP programmers can be used in similar manner such as [USBtiny] or AVRisp mkII. During ISP, mic should be disconnected, power supply should be connected; in tool do not erase, program EEPROM or set fuse settings (they are by default ok: E=FD H=D1 L=F7).
+- [AVRDudess] tool or avrdude CLI (avrdude -c avrisp -b 19200 -P /dev/ttyACM0 (or: /dev/ttyUSB0) -p m328p -e -U efuse:w:0xFD:m -U hfuse:w:0xDE:m -U lfuse:w:0xFF:m -U flash:w:R1.0x.hex) can be used for uploading the firmware via the ISP connector on the QCX. Follow [Arduino as ISP] instructions if you have a Arduino UNO board available (tip: use female-to-male breadboard cables to connect Arduino to QCX ISP jumper); or [USBasp] instructions if you have a USBasp programmer, alternatively use [USPasp ExtremeBurner]; but many other ISP programmers can be used in similar manner such as [USBtiny] or AVRisp mkII. During ISP, mic should be disconnected, power supply should be connected; in tool do not erase, program EEPROM or set fuse settings (they are by default ok: E=FD H=DE L=FF).
 - Alternatively, in case you have an ATMEGA328P chip with Arduino bootloader, you can place the chip in an Arduino UNO board and upload directly (without the need for a ISP cable and QCX) by specifying 'arduino' programmer and baudrate 115200.
 - Alternatively, in case you have an [Arduino 1.8.9] (or newer) environment installed, you can upload the [QCX-SSB Sketch] directly from the Arduino environment (without using AVRDudess and firmware file); make sure "Tools > Board > Arduino/Genuino Uno",  "Tools > Port > /dev/ttyUSB0 or ttyACM0", and then "Sketch > Upload" is selected, while the ATMEGA328P chip is placed in the Arduino UNO socket. It is also possible to use [Arduino as ISP] method: upload this variation of [ArduinoISP] to the Arduino board and select "Tools > Programmer > Arduino as ISP", and "Sketch > Upload Using Programmer".
 2. <a name="note2"/>The occupied SSB bandwidth can be further reduced by restricting the maximum phase change (set MAX_DP to half a unit-circle _UA/2 (equivalent to 180 degrees)). Audio-input can be attenuated by increasing parameter MIC_ATTEN (6dB per step).