8m - I/O ADC 2 - Not working

E

EdgerRel

New Member
Hi - I am new to electronics so there is a chance this is something I am doing wrong. I am building a PWM motor controller using the picaxe 8m. I had the prototype circuit working well until all of the sudden the I/O ADC 2 pin stopped working. I set up a simple program like the below but an LED won't light. Do these pins go bad or do I need to do something differently? I tried deleting the old software and reinstalling but still the same result. Please help.

Code: 
main:
   high 2
   pause 200
   low 2
   pause 200
   goto main
Thanks,
Nick
 
S

slurp

Senior Member
I think Mycroft is right but what did you have connected when you tried to PWM the motor?

regards,
colin
 
E

EdgerRel

New Member
Connected

I figured as much.

Pin 1: +5v from LM7805 and .001uf Capacitor
Pin 2: 22k resistor to 10k resistor (to ground) and TX serial cable
Pin 3: n/a
Pin 4: n/a
Pin 5: 10k resistor (to ground) and TC4427 Mosfet Driver
Pin 6: Output of Hall Sensor
pin 7: RX Serial Cable
Pin 8: Ground and .001uf Capacitor (from +5v)

This was built from a schematic online and of course it could be wrong. I would welcome any insight.

Thanks,
Nick
 
A

alband

Senior Member
Do the other pins work:
Code: 
main:
   high 0
   pause 200
   low 0
   pause 200
   high 1
   pause 200
   low 1
   pause 200
   high 4
   pause 200
   low 4
   pause 200
   goto main
 
T

tiscando

Senior Member
EdgerRel said:
.001uf Capacitor
Click to expand...
>1nf (1 nanofarad)

examples:
1TB(1 terabyte)=1,000,000,000,000 bytes (e12) 'soon, data capacities for hard drives could be measured in TB rather than hundreds of GB.
1GB(1 gigabyte)=1,000,000,000 bytes (e9)
1MHz(1 megahertz)=1,000,000Hz (e6)
1kHz(1 kilohertz)=1,000Hz (e3)
1mF(1 millifarad)=0.001 farads (e-3)
1uF(1 microfarad)=0.000 001 farads (e-6) 'due to ohm's law, one farad is very large.
1nF(1 nanofarad)=0.000 000 001 farads (e-9)
1pF(1 picofarad)=0.000 000 000 001 farads (e-12)
 
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E

EdgerRel

New Member
alband - Yes they do. Which is weird. I figured if I fried the chip, I'd fry the whole thing. Doesn't make sense that just one pin would die. However, I'm not totally sure how these things work on a micro-level.

tiscando - Um. Yes. you are correct. Thank you for converting my units.
 
A

alband

Senior Member
How did you get the other outputs working - what circuit?
If it was the same circuit can you try making a bare essentials circuit on a breadboard to see if it works.
One extra thought: if you're using a PCB currently, are you sure no cracks have developed in the track at out2? If you do test in a breadboard and therefore have the PCB de-chipped, use a multi-meter to check for breaks or any other irregular readings.

If all else fails, you may have damaged the chip somehow.
Technical: is there any way to test if there is some problem with a specific I/O port? e.g. resistance between the problem leg an GND?

Good luck. :D
 
C

Charlie_M

New Member
Hi all,

The ADC 2 pin is a analog input.Not a digital output. So blinking a led is not a option.At least I think.
 
W

westaust55

Moderator
Charlie_M said:
Hi all,

The ADC 2 pin is a analog input.Not a digital output. So blinking a led is not a option.At least I think.
Click to expand...
Suggest you look at the Manual 1 page 6 and then at Appendix D (pages 79 to /80) and you will see that Physical Pin 5 can be Digital In 2, Digital Out 2 or Analogue In 2 plus PWM2 or the Tune output.


EdgeRel,

It is likely that you have cooked one of the output transistors (for Output2) inside the PICAXE if all the other IO is working.

wrt to capacitor "size" units, while many do use nanoFarads its not compulsory. 0.001uF still makes sense.
Its like metres - we tend to use mm, cm, m and km but not dm (decimetre 1dm = 100mm). Other units are often used in the same manner.
Think
 
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