I soldered on the headers to connect the Ardupilot Mega to the Oil Pan IMU shield. (I'm still waiting for the 3x8 right angle headers...those aren't on yet) When I hook it up to my computer via USB, there is a loud, sort-of clicking sound. You can get the general idea from the video. If I had to pinpoint the sound, it sounds like it is coming from the Relay. Any ideas?
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It turns out it wasn't anything I did wrong and the problem was actually with the ArduPilot Mega.
Using a multimeter on the relay switch of the IMU, there was AC passing through that was causing the relay to rapidly turn off and on; hence the clicking noise. As seen in the highlighted part of the board schematic attached, a pin on the relay is connected with the header pin located directly underneath the 'ua' of 'Dual 3.3V Reg'.
If you match that up with the ArduPilot Mega, it is pin PL2. Again using the multimeter, there was a short between PL2 and PL3 of the ArduPilot Mega. Tracing these, they go into the ATMEGA 1280 chip.
If you look at the schematic online, they correspond to pins 37 and 38; pins that are right next to each other.
Even looking underneath a magnifying glass, I couldn't see anything in the between the soldering joints holding on the ATMEGA 1280, but I took the smallest needle I could find, and ran it through the spacing. Then, measured the resistance between PL2 and PL3 again and voila, no short! I put the boards back together, hooked it up via mini usb and no more clicking!
As a side note, I'm not sure who here made the schematic for the IMU, but I believe the relay was drawn incorrectly to how it actually is on the board. I think it should look like this:
Thanks for the links to the schematics...I have the same thing happen to me as Chris; it prompts for a login to google docs.
I went over everything with my soldering iron again and I still get the sound. Does it mean anything that the sound only appears when the IMU is paired with the ArduPilot mega? Could it possibly have anything to do with not having the 3x8 right angle headers on?
I've got the mega beta board and the new mega shield working, but I do not have that sound issue at all. I've successfully run the teaser code, plus the new arducopter (mega) code, and the beta ardupilotmega_1_0. And so far the attitude gyros/accel output are working great. The code the guys are working on is looking real close to being flight ready... cant wait :)
Joined the ArduPilot Mega and the Oil Pan IMU minus the 3x8 right angle header pins.
Installed Arduino 0018.
Connected a mini usb cable from my computer to the mini usb port on the IMU while it is joined with the ArduPilot Mega.
Computer successfully installed drivers
Opened ArduPilotMega_Demo and made sure I had Arduino Mega and the correct COM selected
Uploaded the code successfully
In the serial monitor at 57600 baud, "Ch0:1500 Ch1:1500 Ch2:1500 Ch3:1500 Ch4:1500 Ch5:1500 Ch6:1500 Ch7:1500" was output over and over again.
The clicking sound persists through all of this and I think it made the sound before I uploaded code. Every once in a while the sound will stop for about a second and then start again.
I looked at all of my solder joints and don't see any of them connected with each other. Is that what you wanted me to check? I can try to find a magnifying glass and look at them more closely.
I don't get this with either the teaser code or the ardupilot mega demo code so you must have a bad solder or bad part. Have you tried a "hello world" application on there that does nothing?
I mated my ArduPilot Mega with the IMU Meg last weekend, but did not experience the clicking sound heard in your video. Have you double checked all of your solder joints? Also, what code are you running on the ArduPilot Mega. Mine was running the ArduPilto Mega Demo program that tests the RC functions.
Replies
It turns out it wasn't anything I did wrong and the problem was actually with the ArduPilot Mega.
Using a multimeter on the relay switch of the IMU, there was AC passing through that was causing the relay to rapidly turn off and on; hence the clicking noise. As seen in the highlighted part of the board schematic attached, a pin on the relay is connected with the header pin located directly underneath the 'ua' of 'Dual 3.3V Reg'.
If you match that up with the ArduPilot Mega, it is pin PL2. Again using the multimeter, there was a short between PL2 and PL3 of the ArduPilot Mega. Tracing these, they go into the ATMEGA 1280 chip.
If you look at the schematic online, they correspond to pins 37 and 38; pins that are right next to each other.
Even looking underneath a magnifying glass, I couldn't see anything in the between the soldering joints holding on the ATMEGA 1280, but I took the smallest needle I could find, and ran it through the spacing. Then, measured the resistance between PL2 and PL3 again and voila, no short! I put the boards back together, hooked it up via mini usb and no more clicking!As a side note, I'm not sure who here made the schematic for the IMU, but I believe the relay was drawn incorrectly to how it actually is on the board. I think it should look like this:
I also uploaded the changed file.ArduPilotMegaShield_F_v141.sch
I went over everything with my soldering iron again and I still get the sound. Does it mean anything that the sound only appears when the IMU is paired with the ArduPilot mega? Could it possibly have anything to do with not having the 3x8 right angle headers on?
Thanks for the replies everybody
If I hook up only the IMU to the computer, the sound isn't there.
My solders look fine as far as I can tell, but tomorrow I'll heat each of them up again to make sure I don't have a cold solder somewhere.
Joined the ArduPilot Mega and the Oil Pan IMU minus the 3x8 right angle header pins.
Installed Arduino 0018.
Connected a mini usb cable from my computer to the mini usb port on the IMU while it is joined with the ArduPilot Mega.
Computer successfully installed drivers
Opened ArduPilotMega_Demo and made sure I had Arduino Mega and the correct COM selected
Uploaded the code successfully
In the serial monitor at 57600 baud, "Ch0:1500 Ch1:1500 Ch2:1500 Ch3:1500 Ch4:1500 Ch5:1500 Ch6:1500 Ch7:1500" was output over and over again.
The clicking sound persists through all of this and I think it made the sound before I uploaded code. Every once in a while the sound will stop for about a second and then start again.
I looked at all of my solder joints and don't see any of them connected with each other. Is that what you wanted me to check? I can try to find a magnifying glass and look at them more closely.
That happens sometimes when the power supply is shorted/overloaded, and it tries to shut off.
I mated my ArduPilot Mega with the IMU Meg last weekend, but did not experience the clicking sound heard in your video. Have you double checked all of your solder joints? Also, what code are you running on the ArduPilot Mega. Mine was running the ArduPilto Mega Demo program that tests the RC functions.
Regards,
TCIII