Replies to This Discussion

3D RoboticsPermalink Reply by Chris Anderson on March 22, 2009 at 3:26pm

Is the LED on the GPS solid on or blinking? If it's not blinking, you don't have a lock. Indoors, you may never get a GPS lock, and even in the best of times it can take a few minutes. Outdoors, you should get a lock within a minute or two.

• ▶ Reply

Permalink Reply by barkerzd on March 22, 2009 at 3:30pm

Yes, the LED on the GPS module is blinking, which seems good, as I understand it. The GPS LOCK LED on the ArduPilot board is off however, which is what's confusing me.

• ▶ Reply

3D RoboticsPermalink Reply by Chris Anderson on March 22, 2009 at 3:37pm

That's not right--you've got something loaded wrong.

Please confirm that you have it set up exactly like the diagram (except without the FMA Co-Pilot and ailerons and elevator servos, of course).

Also, with ArduPilot running and the FTDI cable connected, what do you see in the Arduino IDE's serial monitor (don't forget to set the baud to 4800)?

Finally, is the MUX LED responding properly to turning the CTRL channel toggle on and off?

• ▶ Reply

Permalink Reply by barkerzd on March 27, 2009 at 9:48pm

Hi Chris,

Sorry for taking so long to get back to you; I've had a pretty busy week and haven't had much time to play around with my AP project until now.

My setup differs from the diagram only in that the throttle and steering are setup to be Channel 2 and Channel 1 respectively on my Futaba RC car receiver, not Channel 3 (throttle) and Channel 4 (rudder) as you mention in the ArduPilot Assembly Instructions post. The entire setup is as follows: the steering servo is connected to AP OUT 2, there is a dummy servo in place of my ESC connected to AP OUT 1, the AP IN 1 is connected to Channel 3 on my RX, and the AP IN 2 is connected to Channel 1 on my RX (not Channel 4 as in the diagram). My ESC is connected directly into Channel 2 of my RX so I can manually control the throttle. I have AP CTRL connected to Channel 4 on my RX, but I'm not sure if this is what's causing me trouble. This has confused me so far since my TX/RX setup (Futaba T4GWD-AM) doesn't have a toggle switch. To remedy this, I've tried ignoring the MUX through the software as you suggested in a previous post. Are there any ways that I might be able to achieve this through some sort of hardware solution?

So after uploading the modified sketch files (to ignore MUX), I placed the entire RC car setup near a window for ~10 min. to get a GPS signal, which is achieved in ~5 min. as indicated by the blinking LED on the GPS module (but still no blue GPS LOCK LED). During the entire time the AP is searching for a GPS signal, the MUX, STAT, and MODE lights are flickering and the steering and dummy throttle servos are twitching. This behavior continues even after the red LED on the GPS module blinks to indicate a GPS signal lock. Looking at the serial monitor during this time shows long periods where only "Waiting for fix position" is displayed followed by long periods where only "ArduPilot!!!" is displayed. Occasionally, some data like "Mot: 0 Yaw: 60 Alt:0 Crs: 0 Dis: 36928 Des: 180" will be displayed, but only very briefly on one line. After ~15 minutes of a blinking GPS module LED, but no AP GPS LOCK LED or meaningful serial monitor data, I turned the entire unit off.

Finally, is there any way to limit the maximum speed of my ESC through the software? I have tried a few things, but nothing has worked so far. If I could do this, I could have the car navigating very slowly on its own, without me working the throttle on my TX. This would also simplify my very confusing setup as described above, I think.

Does any of this sound like it might be causing a problem? What changes might I need to make to my wiring to and from the AP board? Thanks again so much for your help.

• ▶ Reply

3D RoboticsPermalink Reply by Chris Anderson on March 27, 2009 at 11:26pm

ArduPilot was not set up to be used without an input on the CTRL channel. But there is a way to solder a wire from a spare digital pin to the TMISO pin and tell the software to set it high, simulating the MUX turning on. Consult the schematic for more.

• ▶ Reply

Permalink Reply by barkerzd on March 28, 2009 at 11:21am

This would be connecting the pin labeled "D6" on the board with the signal pin on the CTRL channel, correct? Then I would just need to modify the ArduPilot code as GhostRider did in this post?

By the way, has anyone that you know of tried controlling the maximum speed of their ESC using the AP code? That's my next problem to tackle after this one...

Thanks again for your help.

• ▶ Reply

3D RoboticsPermalink Reply by Chris Anderson on March 28, 2009 at 12:24pm

Correct.

• ▶ Reply

Permalink Reply by barkerzd on March 28, 2009 at 12:26pm

OK, I'll give it a try. Thanks.

• ▶ Reply