charlesplatt
Member
For the very beautifully made Futaba digital servos, Futaba tech support absolutely insists that the neutral-center command has to be a 1500us pulse.
This appears to be incorrect. I have run numerous tests using the SERVO command on a PICAXE 08M, and 1310us sets the neutral-center position.
Futaba tech support insists that 1310us dates back to very old analog servos, but, I have this thing right in front of me, centering itself when I send a SERVO 2,131 command.
What about the ends of the rotational arc? Futaba tech support sez, "send a pulse anywhere from 1000us to 2000us." Well, this is incorrect also. My digital servo DOES NOT RESPOND to a 2000us pulse. (How about yours?) Laborious trial and error shows that it responds within this range only:
"Low" end: 680us
Center: 1310us
"High" end: 1940us
Since the SERVO command divides microseconds by 10, you can use any number in the range 68 to 194.
If you send SERVO commands outside this range, the servo ignores them. This makes perfect sense since it is a DIGITAL device and you may notice that the range I have stated above allows 127 steps of 10us each. In other words the servo probably has a 7-bit internal controller.
What about frame rate? Some say a digital servo requires more than 50hz. Futaba tech support says 50hz is fine. I think a more accurate statement is that the servo will tolerate faster frame rates, but mine works fine with the PICAXE 08M sending pulses at 50hz.
I hope this info may help some users who may otherwise be as frustrated as I was, wrestling with this problem yesterday. As for Futaba tech support, they got tired of arguing with me.
This appears to be incorrect. I have run numerous tests using the SERVO command on a PICAXE 08M, and 1310us sets the neutral-center position.
Futaba tech support insists that 1310us dates back to very old analog servos, but, I have this thing right in front of me, centering itself when I send a SERVO 2,131 command.
What about the ends of the rotational arc? Futaba tech support sez, "send a pulse anywhere from 1000us to 2000us." Well, this is incorrect also. My digital servo DOES NOT RESPOND to a 2000us pulse. (How about yours?) Laborious trial and error shows that it responds within this range only:
"Low" end: 680us
Center: 1310us
"High" end: 1940us
Since the SERVO command divides microseconds by 10, you can use any number in the range 68 to 194.
If you send SERVO commands outside this range, the servo ignores them. This makes perfect sense since it is a DIGITAL device and you may notice that the range I have stated above allows 127 steps of 10us each. In other words the servo probably has a 7-bit internal controller.
What about frame rate? Some say a digital servo requires more than 50hz. Futaba tech support says 50hz is fine. I think a more accurate statement is that the servo will tolerate faster frame rates, but mine works fine with the PICAXE 08M sending pulses at 50hz.
I hope this info may help some users who may otherwise be as frustrated as I was, wrestling with this problem yesterday. As for Futaba tech support, they got tired of arguing with me.