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servo controller

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flipflop

New Member
hello.
im looking for c code for programing pic
to controll 8 servo motors.
the pic shold get serial string from the serial port(rs-232)
and drive 8 sevos,each servo have to get puls between
1-2msec.
ill be very gratefull for some help:)
flipflop.
 

SparkFun

New Member
Servo Driver

This is very possible, but it ain't easy.

Because your pulse width is so short (1-2msec) you don't have much time to be reading the incoming serial info. At 9600 baud it would take 1ms to transmit 10 bytes of data (start/stop bytes and 8 bytes of servo data). So every time you transmit to your servos, you may get a blip or hickup in your servos (not good).

Now if you setup the hardware UART with interrupts - you will have no problems. You can do plenty in between UART interrupts at 9600. I have controlled 6 motors with direction lines and series of LEDs that were pulse for ilum control (7PWMs and 6 +/- control) without problems.

Operating at 20MHz you should be good to send the appropriate servo PWMs on the PORTB for instance. Just setup 8 software timers and decrement them in time. As each timer goes to zero, load the new timer value (from the uart interrupt info), and flip the appropriate bit on portb. I would not recommend changing each port indiudally - setup a byte and change that byte - in the end write that byte to port b.

Attached is CC5X C code that I wrote to do this. It's big, but it may help.
 

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MW

New Member
Hi all,
Now, I has a project. I want to use AT89C51 to controll servo motor(ac or dc). I have some questions for you:
- Have you got any documents about servo motors?
- On what principle does servo work?
- Can use the AT89C51 to controll servo?


Please nswere on this forum or send to me by email: [email protected]
Thanks and regards! :eek:
 
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