nice job, Randy.
"Looks like I may have a dead one"
well, in my experience these Atmel uC are really quite robust, so I would rather guess that something not easily seen was wrong with the electrical connections... I really have done some things to them which one should not do... and for every one which I thought I killed it later turned out that I did just something wrong, in one instance I actually asked a supplier to take back few devices which I just had bought and couldn't get a single one to flash properly, and the supplier indeed took them back and sent new, but in the meantime I realized that I just had set a flag with avrdude incorrectly...
so, I think eventually it could be worth a try again.
However, for the moment it's maybe not bad that the fuse is not set for one... at least for me... I mean, if you observe "strange" behaviour for this and only this one it's kind of a proof that setting this fuse is really what solves these issues...
So, now that you have essentially all this hard work to get the right bootloaders, fuse settings, and finally the latest firmwares on the robbe box and gyromixer, I think its time to tell you a bit about the behavior of the gyromixer and the interaction with the robbe box.
First, you have two LEDs, a red one and a blue one (unfortunately the red one is not well seen if the blue is on, look carefully, it's easy to get confused here).
The blue one has ONLY ONE function (with one little exception with which don't want to bother for the moment):
The blue LED is ON whenever a connection to the Robbe Box is established, and OFF if not!
You can see that then also on the robbe box, as it offers you the menu setting in case of connection and tells no connect otherwise.
The red LED tells you about the current STATE of the device.
One basically has to distinguish FIVE different states:
A) Initialization and startup
This is the state after having switched on the gyromixer. The gyromixer first waits for a valid signal to come in from the reciever. I think the red LED is blinking very fast.
Once a rx signal has been detected the gyromixer checks for the position of the Thro stick. I think the LED is blinking fast. To positions can be detected:
Thro fully up (Thro high): if the gyromixer detects thro up at startup it enters the B) Thro range programming mode
. That's essentially exactly what you know for the BESCs. That is, as next step you pull the Thro stick to Thro fully down, which makes the gyromixer to store the Thro up and down values of your transmitter/reciever into memory, i.e., you learn it as you do with the BESCs. Once Thro down is detected the two LEDs start blinking alternatively, and the only way to get out of that is to switch off the gyromixer.
IMPORTANTLY, during all times in this this mode the Thro signal from the rx is send through 1 to 1 to the two motor outputs of the gyromixer. That is, in this mode you also can learn BOTH BESCs.
Thro fully down (Thro low): if the gyromixer detects thro down at startup it moves on and enters the various normal operation modes, see next.
Once the initialisation steps have passed, the gyromixer can be in either one of three modes, Thro low mode, Flight mode, and Failsafe.
C) Thro low mode:
This mode is entered whenever the gyromixer detects that the Thro stick is low for longer than 4 seconds. The red light will then permanently go on.
In this mode a signal is output to the motor outputs, but the rudd, gyro, and mixer functions are off.
D) Flight mode:
If the Thro is moved up a tiny bit (3% of the full range if the gyromixer was learned), the gyromixer enters the Flight mode and the red LED goes permanently off. In this mode the motor BESCs get their signals and the gyromixer does what you expect it to do.
If a loss of a valid signal from the reciever is detected, the motor signals are slowly reduced to minimum. However, if within this period a signal is comming in again, the motor signals will go back to what they are supposed to be. During Failsafe, the red LED blinks fast.
IMPORTANTLY: A connection to the Robbe Box is ONLY possible if teh gyromixer is in STATE (A), (B), (C)!
(PS: I will change the code in the near future, because now it means that if you are in Thro low mode (C) and switch off the transmitter, which one may wish to do for e.g. safety, the gyromixer enters failsafe mode (E) and a connection to the robbe box is not possible, which is inconnvenient, hence I will change the code such that in Thro low mode a Failsafe is does not affect the communication with the robbe box. Thanks to Tommy@LA for bringing this up).
Before we go into the parameter settings, I suggest that you familarize yourself with these modes and robbe box connections. A lot of potential later problems/missunderstandings/confusion can be avoided this way.