polo-g40
Full Member level 2
First Post, Just built a my first "robot" &(SLA7029M)
I've just build my first microcontroller based moving-accross-a-floor object and would like to introduce myself with it. It is made out of an old CD drive case, 2x1.5A stepper motors, PIC16 stuff (MCD2 and a DemoII board (pic16.com)) and a driver board with 2xSLA7029M's on . It can harldly be described as a car at the moment, having only 2 6inch wheels and half a golf ball to hold the front up so far. )
This site has been one of the places I have learned a lot from over the last 6 months of fiddling with PICS, Darlingtons, H-bridges, steppers and 3phase DC motors.
I've been trying just to make my car move using Pic (16f628) to start with and LN darlington chips. I went through quite a few chips and drivers having trouble controlling the power going to it.
Looking through my many "scrapped photocopier bits" I came across this board, I think it was from an HP, it had little on it but a few connectors, an MCU, 2 large upright IC's and 1 extra large IC with a heatsink (BiPolar driver). There were some of the familiar 6 wire connectors, some big capacitors, and a groundplane. The 2 IC's were SLA7029M's and are PWM power controllers for 6wire steppers. A quick look at the datasheet and I was on its case. Things didn't seem hopeful to start, I searched on all sorts of places and there seem to be only people struggling with these chips, luckily mine was on a working board. They looked just the job, over an amp without heatsink, more probably. A look at the datasheet made it look a nightmare to start but.....
All I did was solder directly to A and B pins out of the IC's and the 2 phase-disable (tdA&tdB) pins. They went straight to into a controller (datasheet provided signal orders), then soldered 12v directly onto a big cap, and the steppers into their sockets, and bingo, off it went.! Sort of.....I had to supply the chip with a reference voltage (used a pot between 0-12v) to control the PWM level. A pain was I had to make the disable A&B inputs from the controller a very specific resistance to let the PWM work (fidling with a salvaged twin-wiper volume control. (the chip uses the disables for the PWM, when the voltage across a shunt resistor is above the "ref" mentioned that phase shuts off at khz. These do chips stay amazingly cool compared to the LN's.
So, future alterations I recon I need to look at, I intend driving the Ref pin voltage with an output from the Pic, add some proximity sensors (photocopier paper sensors), add infra-red remote support. And, a PS2 Mouse, as feedback so it knows when its stuck. Possibly a microphone too for the same purpose. If I can, I am going to make it balance too, hopefully using I2c gyro sensors, but lets see eh.!
Regards
NEAL
:grin:
I've just build my first microcontroller based moving-accross-a-floor object and would like to introduce myself with it. It is made out of an old CD drive case, 2x1.5A stepper motors, PIC16 stuff (MCD2 and a DemoII board (pic16.com)) and a driver board with 2xSLA7029M's on . It can harldly be described as a car at the moment, having only 2 6inch wheels and half a golf ball to hold the front up so far. )
This site has been one of the places I have learned a lot from over the last 6 months of fiddling with PICS, Darlingtons, H-bridges, steppers and 3phase DC motors.
I've been trying just to make my car move using Pic (16f628) to start with and LN darlington chips. I went through quite a few chips and drivers having trouble controlling the power going to it.
Looking through my many "scrapped photocopier bits" I came across this board, I think it was from an HP, it had little on it but a few connectors, an MCU, 2 large upright IC's and 1 extra large IC with a heatsink (BiPolar driver). There were some of the familiar 6 wire connectors, some big capacitors, and a groundplane. The 2 IC's were SLA7029M's and are PWM power controllers for 6wire steppers. A quick look at the datasheet and I was on its case. Things didn't seem hopeful to start, I searched on all sorts of places and there seem to be only people struggling with these chips, luckily mine was on a working board. They looked just the job, over an amp without heatsink, more probably. A look at the datasheet made it look a nightmare to start but.....
All I did was solder directly to A and B pins out of the IC's and the 2 phase-disable (tdA&tdB) pins. They went straight to into a controller (datasheet provided signal orders), then soldered 12v directly onto a big cap, and the steppers into their sockets, and bingo, off it went.! Sort of.....I had to supply the chip with a reference voltage (used a pot between 0-12v) to control the PWM level. A pain was I had to make the disable A&B inputs from the controller a very specific resistance to let the PWM work (fidling with a salvaged twin-wiper volume control. (the chip uses the disables for the PWM, when the voltage across a shunt resistor is above the "ref" mentioned that phase shuts off at khz. These do chips stay amazingly cool compared to the LN's.
So, future alterations I recon I need to look at, I intend driving the Ref pin voltage with an output from the Pic, add some proximity sensors (photocopier paper sensors), add infra-red remote support. And, a PS2 Mouse, as feedback so it knows when its stuck. Possibly a microphone too for the same purpose. If I can, I am going to make it balance too, hopefully using I2c gyro sensors, but lets see eh.!
Regards
NEAL
:grin:
Last edited:
