Recommendations - Model Train Controller

[malc-c]

Hi, Steve

Did you notice a 1K resistor had magically appeared in series with the trans. base ??? ...

Alain, the 1K base resistor was added way back after you suggested in post #46 that I removed the R4/D1 combo and and a series 1 k in the base connection

The nearest shematic I have is as detailed in post #57 - apart from the fact that I'm using a 16F676 rather than the 12F675 - the output stage is the same, I've not changed anything since, and wouldn't edit posts to suit...

[Darrel Taylor]

Malcolm,

I've got it running here on a 16F676. But...

You have a POT input on AN3, which is also the OSC2 for the crystal.

If I comment out the ADCIN 3, DUTYVAR4 then it seems to run fine.
But with that statement in there it goes wacko.
<br>
Added: ANSEL needs to be changed too, but I'll wait to see where you move the AN3 to.

[malc-c]

Whoops !

Thanks for spotting my deliberate mistake !!!!

Thanks for the PM, I've created another copy of the code and downloaded the DT_int 18 file, the following compiles OK but I have to use a different programmer for pics with 18 pins or more and I've never had much luck with 18F2550's and this programmer as Steve will vouch !!

I'll try some changes for the 16F676 and see how I get on.. Thanks to everyone again for your assistance...

[malc-c]

Malcolm,

ANSEL needs to be changed too, but I'll wait to see where you move the AN3 to.

I actually marked it on the datasheet pinout to use AN4 (pin 10) on the 16F676 - I should pay more attention to what I plan !!

[Darrel Taylor]

AN4, ok.

Make ANSEL = %00010111
<br>

[malc-c]

AN4, ok.

Make ANSEL = %00010111

Darrel, can you confirm that I have understood the variables for SPWM_PIN right, and that I'm using the correct channels for a/d, as I only had 2 out of 4 outputs working right, and now made changes I get that high frequency noise from the armature (where as before it was a low growl, even with a 20 Mhz xtal)

I want to use the following pins on the 16F676 for inputs from 10K pots, and their corresponding PWM outputs

Pot 1 - Pin 13 - AN0 - controlling output on pin 8 - RC2
pot 2 - Pin 12 - AN1 - controlling output on pin 5 - RC5
pot 3 - Pin 11 - AN2 - controlling output on pin 6 - RC4
pot 4 - Pin 10 - AN4 - controlling output on pin 7 - RC3

so I've set up SPWM_PIN as

SPWM_LIST  macro                    ; Define Pin's to use for SPWM
    SPWM_PIN  PORTC, 2, _DutyVar1   ; and the associated DutyCycle variables
    SPWM_PIN  PORTC, 5, _DutyVar2   ; Notice the underscore before variables
    SPWM_PIN  PORTC, 4, _DutyVar3
    SPWM_PIN  PORTC, 3, _DutyVar4

And have the main program as

Main:                               
 ADCIN 0, DUTYVAR1
 ADCIN 1, DUTYVAR2
 ADCIN 2, DUTYVAR3
 ADCIN 4, DUTYVAR4
 GOTO Main

I'm assuming the value of ANSEL is incorrect as its ommitting that high frequency noise. Given the above info, which I hope is clear, what would be the correct value for ANSEL, or have I made another boo boo in assignig the pins ?

By the way, prior to the change I had it running really well on CH1 - you thought that on a 12F @ 4mhz the loco was slow.... wait to you see the video for it running on a 16F @ 20 mhz !! - its just amazing !!

[malc-c]

Darrel,

Here is that video - http://www.micro-heli.co.uk/controller2.avi

I've left the audio element in so you guys can hear the growling the loco makes, the downside is that this has made the file 24MB

[Acetronics2]

No secret, Malc ...

PWM freq too low.
( may be also a poor quality motor too ... but you can't choose which will be used.)

Alain

[Acetronics2]

Alain, the 1K base resistor was added way back after you suggested in post #46 that I removed the R4/D1 combo and and a series 1 k in the base connection

The nearest shematic I have is as detailed in post #57 - apart from the fact that I'm using a 16F676 rather than the 12F675 - the output stage is the same, I've not changed anything since, and wouldn't edit posts to suit...

We're in sync Malc ... just R3 NOT to be shorted !!! ... but placed in series with the NPN COLLECTOR ...

MEA Culpa ...

Alain