So I get my new APM in the post, excitedly open it connect a few servos, upload the dancing firmware test and.... nothing. Jitter and a crazy flashing mux led.
Anyway to cut a long story short it seems the PPM chip has not been programmed right by Sparkfun. I tried following the steps here,
using the manual process, but found that even though the source from here,
compiles and uploads fine, the chip still doesn't work.
So reading the fuses I notice that the brown out was set to 4.3v which seems quite high, more than likely the issue. So I set it to 1.8v hit program and voilà it all works nicely.
Looking through Jordi's batch file confirms this as this is the setting used in the batch.
Here is the old settings:
Here is the old settings:
And the new:
So the process is this:
- Connect up the APM to your programmer (follow the guide for programming firmware)
- Go to the fuses tab and click read
- It should show the extended fuse setting as 0xFC and brown out show as 4.3v (as the first image)
- You can then either set the drop down to 1.8v OR change the setting directly to 0xFE in the lower section
- Then hit program, check all the status messages are ok
- For double confirmation, click read again
- The settings should now be 1.8v / 0xFE
For me this fixed the PPM chip and now the dancing servos program works fine.
My personal preference is to de-solder SJ1 and power the radio gear & APM separately.
On the desk the APM uses the usb (for power and serial debug) and I use a bench supply for the servos (connected to input channel 8).
In the air, I use one of the ESCs (quadrotor) to power the radio etc and a separate BEC/regulator connected to the battery for the APM (connected to the power header).
