Hello! And parallax standard servo range of motion for 500-1000 pulsout durat
Bogatyr
Posts: 2
Hello! I'm a new BS2 owner (Basic Discovery Kit) -- I'm a career software architect (I've always worked for HW companies though -- device drivers, some functional architectural HW design, HW/SW interfaces, etc.) with a smidgen of intro EE background (college) and a digital design lab (some combinational logic, flip-flops, registers, muxes, etc.) but no analog sensor / motor driving experience. I got the kit to introduce my kids (two boys, 12 and 14) to electronics and so far have been hogging the kit myself, re-learning the basics, having a blast. Built the 3-bit DAC via the R2R ladder from the Dietz EE course on the parallax CD and really had fun analyzing the circuit on paper, then building a working version that matched the theory. That's the sort of thing I hope to introduce my kids to, relating theory to practice and building fun things. So far the kit is proving a great investment, especially with all the downloadable materials.
I have a BoE board from a Basic Discovery Kit with a Parallax standard servo. I'm powering the BoE with a battery holder with 6 Nimh AAs, fairly high rated (4 2500 maH and 2 2000 maH). They're freshly charged and the Vin I'm seeing is > 8V. I've gone through the servo chapter in the What's a Microcontroller? book. I have the servo power jumper set to Vdd (5V, the way the board was set up). When trying out the example programs, I noticed that the 500 and 1000 PULSOUT durations only represented about 95-100 degrees of movement (similar to another user's post I found on this forum from a few weeks ago), leaving a considerable amount of mechanical range on both sides.
The book is fairly adamant about not using any values below 500 or above 1000, but isn't what's really important whether or not the servo is trying to move past the end of its range of motion? I've found that in order to get a full range of motion I need to give values of 250 to 1150, which gives close to 180 degrees of movement (+- a few degrees on each end before the motion block is hit).
I've read from some that servos can show significant variation in terms of control durations for leftmost, middle, and rightmost positions. Does my range( pulsout 250 to 1150) seem unusual? Could there be something wrong in my setup, or is this within the normal servo variation?
thanks!
I have a BoE board from a Basic Discovery Kit with a Parallax standard servo. I'm powering the BoE with a battery holder with 6 Nimh AAs, fairly high rated (4 2500 maH and 2 2000 maH). They're freshly charged and the Vin I'm seeing is > 8V. I've gone through the servo chapter in the What's a Microcontroller? book. I have the servo power jumper set to Vdd (5V, the way the board was set up). When trying out the example programs, I noticed that the 500 and 1000 PULSOUT durations only represented about 95-100 degrees of movement (similar to another user's post I found on this forum from a few weeks ago), leaving a considerable amount of mechanical range on both sides.
The book is fairly adamant about not using any values below 500 or above 1000, but isn't what's really important whether or not the servo is trying to move past the end of its range of motion? I've found that in order to get a full range of motion I need to give values of 250 to 1150, which gives close to 180 degrees of movement (+- a few degrees on each end before the motion block is hit).
I've read from some that servos can show significant variation in terms of control durations for leftmost, middle, and rightmost positions. Does my range( pulsout 250 to 1150) seem unusual? Could there be something wrong in my setup, or is this within the normal servo variation?
thanks!
Comments
While most Standard Hobby Servo's will have a pulsewidth range from 1ms to 2ms ... which translates to 500 to 1000 when you figure in the 2us resolution of the PULSOUT command. Parallax Servos are designed to operate with a pulsewidth range from 0.5ms to 2.5ms .... resulting in 250 to 1250 when using the PULSOUT command.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.