Posted by Jack Crossfire on December 18, 2009 at 11:39am
So got up to this. Since the reference design has a header which doesn't allow USB & programming simultaneously we now have a header. Unfortunately still no USB even at slow speed. It detects the reset but never gets a transaction.Even in circuit programming is super slow. Maybe that's related to the USB problem. This is the cleanest board we ever made but the programming speed only goes to 9375Hz. Tried disabling the radio, using a bigger capacitor for Vbus, low speed, full speed, direct soldering instead of a header, swapping chips, 5V Vdd, battery & Vbus.The programmer sends 5V through 1k resistors. The USB pins pull it down to 3.3 without burning out. Also tried 2.5V programming levels.
After banging on the 18F14K50 for a week, it was time to put it down & build a conventional 18F2450 ground station with the 18F14K50 as a radio breakout board.A radio & ground station on 1 board isn't very practical. To move the antenna, you need to move the main board & all its connections. Since the MRF49XA requires very fast SPI, that means a 2nd microprocessor on its own board & software to make it look like an XBee.Also, general purpose ground stations which can switch between 900Mhz & 2.4Ghz are more useful if we ever want to fly a pair of 2.4Ghz.For today's video, shot a fully autonomous tree sequence at 1m/s. Still had to input a lot of heading corrections. Didn't have enough battery power to finish the sequence. Unfortunately it appears L1 GPS isn't accurate enough to get very smooth camera motion even at slow speed.You're still stuck with attitude hold & manual flight. There may be an algorithm somewhere which can get smooth motion out of L1 GPS by allowing sloppy position hold but it's not as simple as reducing PID gains. VicaCopter is prone to oscillation if the PID gains aren't high enough.Fortunately the angle of attack at 1m/s was much less. Note velocity oscillation as the computer hunts for 1m/s.
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