18x outputs

[vfxmorley]

Hi all.
Feel REALLY stupid asking this question but Im left with no choice.
Im setting up the 18x for motor control using a L298.
I am also inputting data back from the motors and displaying the output on an LCD.
So currently im using output 0 for the LCD all good with that (now)
Heres my problem. I dont for the life of me understand how to get the other outputs available to me unless i go into the sockets of the IC2. Looking at the layout of the board it seems some outputs dont actually go anywhere.

Please help me understand what Im not understanding. Im sure its going to be one of those.. you idiot moments but im prepared!

This picture has been the clearest image ive found explaining the outputs. So If i go through them all by following the PCB I see the following

pin13 - out7 - terminates on IC1 ie. goes nowhere?
pin12 - out6 - terminates on IC2
pin11 - out5 - terminates on IC2
pin10 - out4 - terminates on IC2
pin9 - out3 - terminates on the PCB but not on the edge
pin8 - out2 - terminates on IC1 ie. goes nowhere?
pin7 - out1 - terminates on IC1 ie. goes nowhere?
pin6 - out0 - looks like it terminates nowhere but I can get access to it (thanks #eclectic http://www.picaxeforum.co.uk/showpost.php?p=106822&postcount=8)


can someone please help explain what it is im missing. The circuit diagram makes me think i can get access to 0, 1, 2, 3 outputs but it doesnt?

thanks for any help

 

[westaust55]

Firstly,
For pictures showing the pin outs for PICAXE chips you only need look at PICAXE Manual 1 page 8.

With respect to the CHI035 board that you have

The datasheet http://www.rev-ed.co.uk/docs/chi035.pdf
Appendix B covers the CHI035.

AT the right side of the schematic lower down there is the note:
"FET and diode repeated for outputs 1 - 3."

So outputs 0 to 3 go to the gates of the 4 FET transistors
and outputs 4 to 7 go to the pins (7, 2 15 and 10 respectively) of IC2

 

[vfxmorley]

on page 8, the layout is as I have been working with

Still doesnt make sense as to how to get access to these outputs?

 

[westaust55]

As indicated in post 2 all of the PICAXE outputs go to other components

Only by virtue of Output 0 going to a test terminal on both the CHI030 and CHI035 as eclectic and I mentioned in recent posts

http://www.picaxeforum.co.uk/showthread.php?p=106478
http://www.picaxeforum.co.uk/showthread.php?p=106822​

is there somewhere other than a component lead at which you can access these signals directly.

EDIT: reference to page 8 at post 2 was only to indicate that the PICAXE pin-outs were available in the Rev Ed PICAXE manuals so no need to link to external websites.

 

[vfxmorley]

As indicated in post 2 all of the PICAXE outputs go to other components

So, I have no way of accessing these ouputs on the 18x board, unless through another component? and by component you mean i need to install the L293 driver into IC2 to get access to the other outputs?

Even though I need to run the L298 for the extra 2A power?

Should I have started with a different board?

thanks
dave

 

[BeanieBots]

You can remove the FETs and simply link what was the gate connection to the output.
There are an assortment of boards for an assortment of applications.

 

[vfxmorley]

You can remove the FETs and simply link what was the gate connection to the output.
There are an assortment of boards for an assortment of applications.

Ok now im feeling really silly here. Im not sure how i know what pins to link.

If I am thinking of running something like the solarbotics L298 board to drive my motors as I require 2A each, so am i best to pair it with the CHI-030 not the CHI-035 as i wont be using the FETs or the L293 chip?

sounds easier to start with the 30 so I have easier access to the output pins

Or can you diagrammatically show me what links i would need to make on the 35 to allow me to link in the solarbotics board

thanks for your help

 

[BeanieBots]

It all depends on what you want to do and how much 'tinkering' you are prepared to do.
There are countless options you have. I'll try to list them with the pro's and con's of each.

The best solution is to design your own. Perfect because it's exactly what you want.

Short of that, make use of an existing board, but which one.
If you just want to switch a motor on and off, the high power board can do that. If you want to include direction control, the high power board can still do it but requires the addition of a relay to reverse the motor connections.
(assumes you need greater current than the 293 can supply)

If you specifically want to run a L298, you can use either board with or without modifications.

If you have the board with the darlington driver, simply remove it and replace with a 330R DIL resistor pack. You now have 8 outputs going direct to the board outputs. Nothing could be easier.

Should you still want to use some of the darlington outputs as well, not all is lost. The darlington output can be fitted with a pull-up resistor and then connected to the L298 inputs. It inverts the logic so you will need to invert your commands in your code.

You can use the same trick with the high power board on the FET outputs.
Alternatively, you can remove the FET and link as I mentioned earlier.
To make the link, remove the FET. It has three connections.

With the writing on the FET facing you and the board the right way up, the pin on the left is the 'gate'. This is connected to the PICAXE output.
The pin on the right is the 'drain'. This is connected to the board output.
The pin in the middle is the 'source'. This is connected to 0v.
If you connect the left to the right (without touching the middle) you have connected the PICAXE output to the board output.

IMHO, you would be better off with the darlington version of the board and replace the darlington driver with a 330R DIL resistor pack for 'general purpose' use when PICAXE outputs are required 'as is'.
Rev-Ed supply the 330R DIL resistor pack for this very purpose.