Toto's Traversers

ah ...... that cos you have an Uno, and Toto's shed is so small he needs a nano .

Functionally the nano and uno are the same, so as long as the correct Board type is selected in the tools menu, the program (sketch to be correct ) will be complied and uploaded correctly.

The advantage of the nano is size and cost, the disadvantage is size its small to build test circiuts and you tend to need to mount it on its own board - so I tend to build and test the circuit on the Uno, then transfer the final circuit and program to the nano mounted on a vero board.

The nano costs between £1.50 and £3.00 each depending on the quantity you buy. Toto bought 5 for £10, and my last lot cost £15 for 10.

Paul

 

Now if Mindy was calling you might get a better answer......

a bit of a re-org going on in the railway room, to allow the traverser and Viccy road to co-exist.

More later

Paul

 

Got a delivery today of some A4988 stepper motor driver boards.

So what is a A4988, well this is the controller chip at the heart of the Big Easy Driver (BED), but instead of £20 per BED, I got these for £8 for 5 inc p&p - you can get them cheaper direct from China, but you need to wait 6 weeks.
These chips are used in the RAMPs boards for 3D printers, which use the same Nema 17 motors I'm using for the traverser.

I would still use the BED as first choice, as it makes life easier, in that it provides a regulated power 5V supply for both the arduino and its own A4988 chip and circuitry from the 8- 35V DC supply for the motor.
For the A4988 chip, we need to provide a motor supply, and a 5V supply for the arduino and the A4988 logic circuits. That'll be for another post.

Just to give an idea of the size difference, here is a pic of the Stepper controller on Viccy Road, with the A4988 placed on the Right hand side of the board.



The circuit diagram will follow soon.

Paul

 

Were gonna find out ..........

 

Prototype board made up



Connections

Top Left corner - DCC in, to optoisolator so no electrical connection to the rest of the circuit.
Lower Left hand connector - from the top first pair stepper coil 1, second pair stepper coil 2, Motor DC supply +ve, and last motor supply gnd supply to be 8 to 35V DC.

Right hand middle 4 x manual inputs - there will be more as Toto would like manual control (non-DCC)
Right hand lower - DC in for control circuit 9 - 20V

Along the bottom edge are smoothing capacitors and a 7805 5V voltage regulator.
Green Led is for 5V power is good
Red Led is traverser in motion

Arduino I/O pin connections to the A4988 stepper driver

D2 DCC signal in
D3 Not connected
D4 Direction
D5 Step
D6 Sleep
D7 Reset
D8 MS3
D9 MS2
D10 MS1
D11 Enable
D12 Traverser in motion (Red LED)

MS1 to MS3 set the stepper motor mode full steps or micro stepping 1/2, 1/4, 1/8 or 1/16 th steps.
The sleep and reset pins may be just linked together - but we have flexibility if we need it.

Now I just need to redo the sketch to reflect the changes.

Paul

 

I knew it - this would finally push me on to pharmaceutical drugs





Unable to test the board - battery on my multimeter has failed

Visitors this afternoon, so I will need to visit Tesco's later on for a PP3 - got plenty of every other size.

Paul

 

Maybe you should register the name - P1MRC The Hammer Range

Typical - pick up a battery, fit it and no joy.
Fault finding would be easier if I had a working meter

Traced signs of corrosion around the -ve terminal, peeled back the insulating cover, and lots of corrosion, cut off the connector, and stripped the wire - the copper wire was black.
Traced the wire to its connection on the circuit board and it fell off.
Removed the old wire and replaced with another, and tested good with a direct connection to the battery.
Replacement battery clip ordered from Maplins - collect in the morning.

Aw well - time for bed