# Servo motor control **URL:** \ **Category:** Uncategorized\ **Created:** [17 January 2025 04:52 UTC](https://forum.core-electronics.com.au/t/servo-motor-control/21670 "2025-01-17T04:52:52Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Toni135859](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Toni135859](https://forum.core-electronics.com.au/u/Toni135859)\ **Post date:** [17 January 2025 04:52 UTC](https://forum.core-electronics.com.au/t/servo-motor-control/21670/1 "2025-01-17T04:52:52Z")
Can someone advise me the formula to convert microseconds to degrees of rotation. I am using an SG90 and know the range of microseconds required but my code (micropython\_pca9685 Servo) uses servo.angle to drive the servo. Thanks Toni ---
**Author:** ![Michael99645](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/michael99645/32/11893_2.png) [@Michael99645](https://forum.core-electronics.com.au/u/Michael99645)\ **Post date:** [17 January 2025 06:20 UTC](https://forum.core-electronics.com.au/t/servo-motor-control/21670/2 "2025-01-17T06:20:15Z")
Are you talking about the pulse width times here ? i.e. a pulse width of X uS = Y degrees of movement If so, the actual number would depend on the servo specs. Can you supply the part no (or a link to the datasheet) for your survo. from there we should be able to work out the math. I dont think there will be a golden rule/mapping. To add some math. example only. Lets say you have a servo The specs of the servo are from 0 - 360 Deg are 700uS - 2300 uS Assuming movement is linear. then my math would be 2300 - 700 = 1600 uS from 0 to 360 Deg 1600 uS/360 = 4.4444 (rounded) uS per Deg so to move 180 Deg. 700uS + (180 \* 4.4444) =\> 700 + 799.992 = 1499.992 uS (approx due to rounding errors) Note: made up numbers in the example and some movement assumptions. ---
**Author:** ![Robert93820](https://avatars.discourse-cdn.com/v4/letter/r/ac91a4/32.png) [@Robert93820](https://forum.core-electronics.com.au/u/Robert93820)\ **Post date:** [17 January 2025 06:58 UTC](https://forum.core-electronics.com.au/t/servo-motor-control/21670/3 "2025-01-17T06:58:13Z")
Hi Toni 360 will not divide evenly into 1000000 so you will only get an approximation. I am still trying to figure out how you get a claimed “precision” servo under these circumstances. Of course if your pulse width can be adjusted in fractions of 1 microsecond you can get closer to “precision” but in most of the text I have seen on the devices used for the hobby market I think the term is used a bit loosely. Cheers Bob Edit add on I have not had great experience with servos but most I have seen are between 1mSec and 2mSec (1000µSec) for 180º and at 90 requires a pulse of 1.5mSec or 1500µSec. That is 5.55555(repeat) µSec per degree I think applies for most common hobby servos. I daresay that more sophisticated applications will have available much better and more accurate servos and the ability to drive them. They probably come with an appropriate price tag also. A bit out of reach for us mere mortals. ---
**Author:** ![Toni135859](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Toni135859](https://forum.core-electronics.com.au/u/Toni135859)\ **Post date:** [19 January 2025 01:24 UTC](https://forum.core-electronics.com.au/t/servo-motor-control/21670/4 "2025-01-19T01:24:22Z")
Thanks to both of you. I think I was complicating the issue, I didn’t need to do the conversion, just stick to angles throughout the code. Its now all working perfectly with the PCA9685/Pico combination driving two SG90 servos via Mosquitto MQTT from the JMRI model rail package on the RPi. Cheers Toni