In the videos below you’ll see that we’ve incorporated our servo into the elevator of the airplane and we’re able to control it using the microcontroller.
In the first video we’ve incorporated the servo into the body of the elevator and it is controlling the trim tab. The microcontroller is still attached to the STK-500 dev board though and it's clearly not a well packaged setup at this point.
In this second video, we’ve removed the microcontroller from the STK-500 and placed it inside a project box that we’ll Velcro inside the airplane.
We did have some questions about how long the leads to the servo can be before there is too much noise coupled into the signal line from the power lines running next to it, but we’ve now tested things by placing about 4 meters of servo wire and had no problem. Should we develop much of a problem we can put some de-coupling capacitors on the servo, and we could always run an I2C or SPI bus to another chip at the rear of the airplane closer to the servo form which the PWM could be generated. Another option would be to use a coax, or other shielded cable for only the signal line instead of lumping it in with the power and ground for the servo. We haven’t seen any problems yet, but there is more testing to be done still.
We did have some questions about how long the leads to the servo can be before there is too much noise coupled into the signal line from the power lines running next to it, but we’ve now tested things by placing about 4 meters of servo wire and had no problem. Should we develop much of a problem we can put some de-coupling capacitors on the servo, and we could always run an I2C or SPI bus to another chip at the rear of the airplane closer to the servo form which the PWM could be generated. Another option would be to use a coax, or other shielded cable for only the signal line instead of lumping it in with the power and ground for the servo. We haven’t seen any problems yet, but there is more testing to be done still.
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