Modern replacement for LM628/629? Servo motor control - Page 1
Forum section: electronics / beginners

author: Photon939
author_rank: Regular Contributor
timestamp: February 14, 2018, 09:21:24 pm
content: I've been looking into the fact that small DC brushmotor servo drivers are not an easy item to find at reasonable prices. The application I have in mind is CNC for stuff like 3d printers and laser cutters. Is there a modern equivalent for the LM629 precision motion controller?https://www.mouser.com/ProductDetail/Texas-Instruments/LM629M-6-NOPB?qs=sGAEpiMZZMvu8NZDyZ4K0Qh6JMP%252bT6SaI'm also open to the possibility of doing brushless motors as well.I'm looking for drivers that integrate with incremental shaft encoders.Thanks in advance for any suggestions.

author: Kjelt
author_rank: Super Contributor
timestamp: February 17, 2018, 10:45:14 pm
content: I was wondering the same thing,my guessis that some things have changed since late 90s when the lm628/629 came out:- cheap steppermotors replaced the brushed dc motors, also then no real need for encoders unless you have heavy usage such as cnc milling where you might loose steps.- microcontrollers have become so cheap and powerfull that semiconductor manufacturers don't see a market anymore. A stm8 for $2 should be able to handle this esp. Dedicated to a single motor and encoder as the lm 62x's do

author: danadak
author_rank: Super Contributor
timestamp: February 19, 2018, 02:11:12 am
content: PSOC Motor Control -http://www.cypress.com/applications/automotive-solutions/motor-controlOnboard DAC, ARM Core, A/D, Digital Filter + a whole lot more....Regards, Dana.

author: Kjelt
author_rank: Super Contributor
timestamp: February 19, 2018, 06:05:06 pm
content: Quote from: danadak on February 19, 2018, 02:11:12 amI don't see the feedback loop (quadrature decoder) which is what makes a motor a servo.

author: perdrix
author_rank: Frequent Contributor
timestamp: February 19, 2018, 06:49:44 pm
content: You may wish to take a look at Microchip AN532 which describes a servo motor control system using a PIC17C42 and a PLD.This was used very successfully as the basis of the dual servo motor controller in the Losmandy Gemini-1 telescope control system.The 17C42 is now somewhat dated, but the concepts and the code are still valid and it could readily be ported to a newer PIC (beware clock rate differences).HtHDavid Partridge

author: danadak
author_rank: Super Contributor
timestamp: February 20, 2018, 12:47:33 pm
content: There is a posted project here, if you have loaded Creator on youPC.http://www.cypress.com/forum/psoc-3-known-problems-and-solutions/servo-motor-interface-psoc-3Here is a BLE application -https://www.embedded.com/print/4458293Regards, Dana.

author: Photon939
author_rank: Regular Contributor
timestamp: February 20, 2018, 09:11:18 pm
content: Quote from: danadak on February 20, 2018, 12:47:33 pmThese projects are not applicable for my project, these are for hobby RC servos which do not have position feedback.

author: Photon939
author_rank: Regular Contributor
timestamp: February 20, 2018, 09:14:51 pm
content: Quote from: perdrix on February 19, 2018, 06:49:44 pmThanks this is the type of application I am looking for. I do have a PSOC from Cypress I got at world makerfaire that might allow me to do all of these digital functions within one chip. I hope I can get the hang of it after being an Arduino scrub for ages.