PICAXE 20X2; an output from PIR causes PICAXE to reset (or goto to beginning)-Fix it?

geditor · Oct 9, 2010

I have a picaxe 20X2 supplied with 5V, using a voltage divider from a 6V source. The PIR (KC7783 - http://www.rapidonline.com/Electronic-Components/Sensors/Pir-Sensors/KC7783R-PIR-Module/80434/kw/PIR) has an output of 5V and when it goes to the PICAXE it causes the program to go back to the beginning again. There is nothing wrong with the program as i've simulated it in programming editor and wrote it myself.

Is the output from the PIR sensor too high? What it the maximum recommended input voltage for the PICAXE input?

I'm a beginner with all this and im having a really hard time with this. haha

Please help
Thank you in advance
JH student
________

Michael 2727 · Oct 9, 2010

Hi and welcome to the forum,

Unless we know exactly what your setup and or code is we are flying blind also.

Dippy says he has a crystal ball, but he never pays the connection fee to the
local Gypsy so it's cloudy most of the time.

A schematic and or code will get you a long way in here, nothing and we are only guessing.

My first educated guess, what values are you using for the voltage divider ??
Did you take into account current through the resistors ?, could something be
drawing most of the power and re-setting the 20X2 ?

More info please.

centrex · Oct 9, 2010

You are going to heaps of replys regarding your power supply or rather lack of it.
Use three 1.5volt cells in series as the power supply and try again.
Please read the manuals re power supplys

John West · Oct 9, 2010

Hi geditor. I'm not from GB but I take it a "JH student" means you are 12 or 13? I just ask because helpful instructions are sometimes a bit different for people of different ages with varying degrees of life experience.

A voltage divider can work as a power supply - but only if there is very little current being drawn by the circuit it powers. This could easily cause the problem you are seeing - if the PIR is also on the same resistive divider power source and it "loads down" the divider when it triggers. I assume you are trying to light an LED or some such load whenever the PIR is triggered. Remember - the PICAXE and whatever else is hooked to it is a part of that divider circuit and any changes in the load will change the voltage at the divider.

As others have stated - if you can show us the code and the circuit we could be more helpful.

geditor · Oct 9, 2010

the reason I haven't used a 4.5 in series is because I have a piezo siren also which needs 6V.

Ok - its late here in the UK so ill upload the circuit tomorrow as i'll have to draw it on TinyCAD first. Also, the PIR doesn't come use power from the same resistive divider.

I'm quite sure the PICAXE power supply is fine because it still sends and displays messages on the LCD display (using the LCD firmware - AXE033) and if I disconnect the output from the PIR to the PICAXE and use another resistive divider switch as the input instead it works fine.

I think the PIR output is too high.... I try limiting the voltage using a small resistive divider tomorrow.

Thanks for your help so far.

John West · Oct 9, 2010

A schematic of your circuitry would indeed be best, as you made no mention previously of the other devices in the circuit or how they're powered, so we are merely guessing until we get more complete info.

"He who knows most - guesses best." - J.W.

MPep · Oct 10, 2010

"He who knows most - guesses best." - J.W.

Too true John, too true.

Haku · Oct 10, 2010

The specs for the PIR you linked to say it can run from 5v, have you tried running it and the Picaxe from a pure 5v source like a regulator? That way you should be sure the PIR won't output a voltage higher than the Picaxe can handle, and you won't need any voltage dividing resistors, just a straight connection from the output of the PIR to the Picaxe.

I have some small PIR modules that take between 5v & 14v (through a diode+onboard 3.3v regulator) and output 3.3v, this is enough to trigger a digital input on a Picaxe running at 5v without problem.

BeanieBots · Oct 10, 2010

As mentioned by many already, we can only guess until a FULL circuit diagram is submitted but I would put money on it being power supply related. A potential divider for power (as has been discussed in other threads) is almost gauranteed to give rise to problems. Such a supply makes proper decoupling even more essential than when using a 'proper' supply method.

Submit the circuit and I'm sure we can sort this very quickly.

Dippy · Oct 10, 2010

Michael is absolutely right, I forgot to pay Lucky Heather for my CSP (Clairvoyant Service Provider).

Wise advice given above.

Anyway, at least you didn't start your enquiry with "So" or "OK" , that's good.

Hopefully, you Circuit schematic will clarify.

You say you are powering the PIR via your Potential Divider circuit.
As described, PD circuits are really lousy for this app.
Why? - consider:
Your PIR triggers and takes a bit more current... if this happens, what happens at the potential divider? What happens to that voltage?
You could calculate the effect, but it may be easier just to measure it with a good DMM or 'scope.
I suspect that extra load is causing your 'PD' supply to be affected, possibly introducing an unwanted transient onto the +V line.

If t'were me I'd throw the PD out of the window and get a Low DropOut (LDO) regulator for 50pence - PD really is a tossy method for most apps and particulary if the load changes and the level is important.
Leave PDs for level shifting Logic or analogue for ADC.

If the PIR still gives trouble then consider powering it off your 6V and feed the O/P to the PICAXE via a 4K7 resistor. Explanations can be given on request.

IMPORTANT. In many circuits the use of decoupling capacitors on PICAXE amd many other chips. Basically one or two capacitors right next to the PICAXE +V and 0v/Gnd pins. They 'absorb' little glitches that could upset the PICAXE. Again, explanations can be given if you want OR you could do a search and look it up for yourself.

Sadly, these things don't seem to get a mention in the Manuals but can very often be of great importance. It is a significant aspect but for some strange reason not deemed important in Rev-Ed Documentation....?

I include decoupling in ALL designs I do. It's a useful 'default' design setting.

One last thing; we are all happy to give guidance, but if this is School Homework or other markable project then we won't (or shouldn't) spoon-feed you with answers.
I know one or two on this Forum cannot contain their desires to impress but they really shouldn't.
Teach a man to fish etc..

geditor · Oct 10, 2010

The program and circuit

The circuit design is shown below (if not, click on this link: http://quickserver.cz.cc/temp/temp-picaxe-design.png)

The program is shown below:

start:
pause 500 'initialize LCD
for b1 = 30 to 0 step -1 'wait 30 seconds after switched on to initiate device
gosub clearLCD
serout b.0, N2400, (#b1)
pause 1000
next b1

gosub clearLCD

serout b.0, N2400, ("Alarm Activated")

do
'wait until there is movement, input from the PIR
loop while pinC.2 <> 1

for b2 = 30 to 0 step -1 'wait 30 seconds until siren (b.2) is high/on - during this time the user can unplug alarm from battery to disable the device
gosub clearLCD
serout b.0, N2400, (#b2)
pause 1000
next b2

b3 = 2
do
high b.2
loop while b3 <> 1 'infinite loop until alarm is switched off

clearLCD:
serout b.0, N2400, (254, 1)
pause 30
return

I made this myself, and it simulates fine. The circuit works fine if I use a small voltage input instead of the PIR from another resistive divider which outputs 3V.

I really don't know what is wrong. Thanks for all your help in advance.
___

Dippy · Oct 10, 2010

Have ANY of the suggestions in previous posts here helped in any way?
Have you actually read and thought about them?
If so, your considered comments would be useful to us.

I couldn't find any image on that link and I'm not really interested in Medical Education or Hair regrowth - but at least we know some more info

Can't you use the "Manage Attachments" button below to upload image?
Or maybe www.tinypic.com can help.

hippy · Oct 10, 2010

I couldn't get that page to load but without a sensible power supply it's not really worth trying to fix anything else; implementing a proper power supply has to be the first step.

Dippy · Oct 10, 2010

That's already been hinted at 4 times and no acknowledgment....

geditor · Oct 10, 2010

Sorry... i should have said in my post last night.... I tried that using a 4.5V, (three AA 1.5V batteries) but then I can't get the siren to work (as well as the LCD display).... I might be wrong, but I think i mentioned it earlier. Sorry...

Any other suggestions; is there a way to get my LCD display (axe033 serial LCD) to operate with 4.5V. I can't get a 5V battery source because I don't really know if that exists. Any help... I'm a real beginner to all this so all your help is truly appreciated

________

geditor · Oct 10, 2010

for some reason the image won't load here... just type into your browser:

http://quickserver.cz.cc/temp/temp-picaxe-design.png

and it should load. Sorry about that :-(
________

geditor · Oct 10, 2010

Dippy said:
Michael is absolutely right, I forgot to pay Lucky Heather for my CSP (Clairvoyant Service Provider).

Wise advice given above.

Anyway, at least you didn't start your enquiry with "So" or "OK" , that's good.

Hopefully, you Circuit schematic will clarify.

You say you are powering the PIR via your Potential Divider circuit.
As described, PD circuits are really lousy for this app.
Why? - consider:
Your PIR triggers and takes a bit more current... if this happens, what happens at the potential divider? What happens to that voltage?
You could calculate the effect, but it may be easier just to measure it with a good DMM or 'scope.
I suspect that extra load is causing your 'PD' supply to be affected, possibly introducing an unwanted transient onto the +V line.

If t'were me I'd throw the PD out of the window and get a Low DropOut (LDO) regulator for 50pence - PD really is a tossy method for most apps and particulary if the load changes and the level is important.
Leave PDs for level shifting Logic or analogue for ADC.

If the PIR still gives trouble then consider powering it off your 6V and feed the O/P to the PICAXE via a 4K7 resistor. Explanations can be given on request.

IMPORTANT. In many circuits the use of decoupling capacitors on PICAXE amd many other chips. Basically one or two capacitors right next to the PICAXE +V and 0v/Gnd pins. They 'absorb' little glitches that could upset the PICAXE. Again, explanations can be given if you want OR you could do a search and look it up for yourself.

Sadly, these things don't seem to get a mention in the Manuals but can very often be of great importance. It is a significant aspect but for some strange reason not deemed important in Rev-Ed Documentation....?

I include decoupling in ALL designs I do. It's a useful 'default' design setting.

One last thing; we are all happy to give guidance, but if this is School Homework or other markable project then we won't (or shouldn't) spoon-feed you with answers.
I know one or two on this Forum cannot contain their desires to impress but they really shouldn't.
Teach a man to fish etc..

Hi... you're right in saying that you shouldn't really spoon feed me.... but i've asked my teacher and he says its OK as the marking is mainly based on the idea of the circuit and the research/write-up in the project therefore, spoon-feeding me is ok

also - asking questions about my circuit is actually part of the project so this is ok

I tried to use a 4k7 and a 10k resistor with still no result. I then tried 22k, but then I think the current is just too low and there is no effect on the PICAXE input.

What exactly happens with the PIR output (without resistors, e.t.c - just normal) and how I know it has reset is that the LCD brief flashes and goes back to the beginning.

I can't try the other stuff (such as the voltage regulator) you mentioned as I don't have those resources at home... When I go to school tomorrow, I'll ask my teacher for these resources and if that fails, then I'll ask him to help or come back to this forum.

Thanks for you help

- much appreciated
________

John West · Oct 10, 2010

geditor:
Your schematic appeared the first time I loaded this page but now it no longer does. I think the image hosting site you are using is loading too slowly - so the Rev. Ed. site is ignoring it. I don't find it at all at the link you send us to.

You might want to recheck which PICAXE pin your schematic shows the serial output to the LCD as originating from. However - that's not the problem. As others here have noted - it's very likely an inappropriate use of a resistive divider for a power supply. One that causes a dip in PICAXE power supply voltage sufficiently large to reset the PICAXE.

My memory of the schematic is not good - but this evening you might try putting an electrolytic capacitor between the PICAXE + supply pin and ground. A thousand or more uFd might work. The purpose of such a capacitor would be to supply a reservoir of energy to support the chip's power supply voltage long enough to see if the reset problem either ceases to occur or takes longer to occur.

This is by no means an acceptable substitute for a properly designed power circuit - but it would likely be able to tell you whether the suspicious divider is truly at fault.

Your thesis that the PIR detector's higher output voltage was causing the reset might be tested with a simple 1K Ohm resistor in series with that device's input on the PICAXE. Such a current limiter would ensure that nothing coming from the PIR could have a negative effect on the operation of the PICAXE.

That's just a couple of things to play around with this evening. Have fun.

Dippy · Oct 10, 2010

Sorry Mate, I'm just getting nonsense from that link.

Try www.tinypic.com .

Powering PIR off 6V and feeding PICAXE is a suggestion I made this morning - obviously it wasn't observed.

I wish you all the best with this project but I find it difficult to suggest anything when I don't know exactly what you are doing.

Please remember, if you want quick and accurate help then YOU have to provide clear and unambiguous information... and make it easily accessible by us.

geditor · Oct 10, 2010

I'm really sorry about the circuit image problem. I've re-uploaded it here:

http://s1188.photobucket.com/albums/z414/gavinschool/?action=view&current=temp-picaxe-design4.png

it seems to be more reliable. if there's any trouble with this one, please tell me.
Sorry again for the inconvenience
________

geditor · Oct 10, 2010

The program is shown below:

Code:

start:
pause 500 'initialize LCD
for b1 = 30 to 0 step -1 'wait 30 seconds after switched on to initiate device
gosub clearLCD
serout b.0, N2400, (#b1)
pause 1000
next b1

gosub clearLCD

serout b.0, N2400, ("Alarm Activated")

do
'wait until there is movement, input from the PIR
loop while pinC.2 <> 1

for b2 = 30 to 0 step -1 'wait 30 seconds until siren (b.2) is high/on - during this time the user can unplug alarm from battery to disable the device
gosub clearLCD
serout b.0, N2400, (#b2)
pause 1000
next b2


b3 = 2
do
high b.2
loop while b3 <> 1 'infinite loop until alarm is switched off


clearLCD:    
serout b.0, N2400, (254, 1)
pause 30
return

________

Dippy · Oct 10, 2010

Aha!

1. As said TWICE(?) before if powering the PIR from the 6V then you MUST have a resistor to the PICAXE input.
2. If you insist on sticking to PD, as said once or twice before put a CAPACITOR across the PICAXE +V and 0V. In any event a capacitor here is highly recommended.
3. I would also suggest putting a capacitor from the Piezo +v terminal to ground. Maybe 100uF. I have seen piezo sounders putting out HORRIBLE amounts of electrical noise.
4. Please try and read people's suggestions, you seem to have ignored quite a few.

Do the PIR people suggest any decoupling on the supply?

You have LCD connected to 6V is that OK?

You don't have Serial-in tied, this could cause some unwanted behaviour.

Read the MANUAL where it says "MINIMUM operating circuit".
MANUAL 1 page 30. Please read the Manual, they are there for YOUR benefit.

geditor · Oct 10, 2010

Dippy said:
Aha!

1. As said TWICE(?) before if powering the PIR from the 6V then you MUST have a resistor to the PICAXE input.
2. If you insist on sticking to PD, as said once or twice before put a CAPACITOR across the PICAXE +V and 0V. In any event a capacitor here is highly recommended.
3. I would also suggest putting a capacitor from the Piezo +v terminal to ground. Maybe 100uF. I have seen piezo sounders putting out HORRIBLE amounts of electrical noise.
4. Please try and read people's suggestions, you seem to have ignored quite a few.

Do the PIR people suggest any decoupling on the supply?

You have LCD connected to 6V is that OK?

You don't have Serial-in tied, this could cause some unwanted behaviour.

Read the MANUAL where it says "MINIMUM operating circuit".
MANUAL 1 page 30. Please read the Manual, they are there for YOUR benefit.

Dippy, thank you very, very, very... much. These seem to be very suitable suggestions. I haven't got any capacitors on me but I will ask for some at school tomorrow and see if this works.

The LCD works fine on 6V. The PIR datasheet doesn't say anything about extra decoupling - the PIR im using (KC7783R) is already decoupled. I can now see the minimum requirements and will do something about this (the serial in part).

I've got a few questions (sorry):
What resistor value should I use for the PIR?
Also, is the capacitor between the 6V source and the V+ on the PICAXE or between the 0V on the PICAXE on the ground? Which capacitor value should I use here - the same 100uF?
The Piezo siren doesn;t have an electrical noise at the moment so, should I bother with the capacitor?

Thank you very much Dippy for all your help in advance.
_______

BeanieBots · Oct 10, 2010

If you go for the strongly advised regulator for the 5v supply, then the datasheet for the regulator will give advice on decoupling.
If you stick wiith the (IMHO dreadful) potential divider method then you will need to take a lot more care over decoupling. (and proabably spend more than a regulator).
You will need both high and low frequency decoupling so will need both electrolytic and ceramic type capacitors.
Fit a 100uF AND a 100nF capacitor across the supply to the PICAXE as close as possible to the PICAXE power pins. Also fit a 100nF across the peizo.
Unfortunately, by putting the 100nF on the peizo to prevent noise from that entering your supply, it will now put a large spike on the supply every time it is switched on, so you should also decouple the 6v line, particularly if it is a dry cell type battery. You can probably get away with 10uF and 100nF for that.
I'd also put 10uF across the LCD display.

For the resistor between PIR and PICAXE input, use a value between 4k7 and 22k. The value is not very critical but having a resistor is essential.

geditor · Oct 10, 2010

BeanieBots said:
If you go for the strongly advised regulator for the 5v supply, then the datasheet for the regulator will give advice on decoupling.
If you stick wiith the (IMHO dreadful) potential divider method then you will need to take a lot more care over decoupling. (and proabably spend more than a regulator).
You will need both high and low frequency decoupling so will need both electrolytic and ceramic type capacitors.
Fit a 100uF AND a 100nF capacitor across the supply to the PICAXE as close as possible to the PICAXE power pins. Also fit a 100nF across the peizo.
Unfortunately, by putting the 100nF on the peizo to prevent noise from that entering your supply, it will now put a large spike on the supply every time it is switched on, so you should also decouple the 6v line, particularly if it is a dry cell type battery. You can probably get away with 10uF and 100nF for that.
I'd also put 10uF across the LCD display.

For the resistor between PIR and PICAXE input, use a value between 4k7 and 22k. The value is not very critical but having a resistor is essential.

ok, thanks very much... I will try this tomorrow... The reason I am not using a voltage regulator is because I was told it would be better not to for this project by my teacher (as the product needs to be as small and light as possible).
________

BeanieBots · Oct 10, 2010

Well, quite simply, your teacher is wrong!
Not only is a PD a VERY POOR way of providing a lower voltage for an active circuit, by the time you have taken all the required precautionary measures and added interfacing (level shifting) circuitry, it would be simpler, smaller and cheaper to use a regulator. Not to mention more reliable, but you've already found that out the hard way.

geditor · Oct 10, 2010

Hahaha... Yeah... I did find that out the hard way. Well, I plan to convince him tomorrow with the voltage regulator. The thing is, all the devices work fine with 6V apart from the PICAXE which need 5V. So would I get rid of all the capacitors you mentioned if I used the voltage regulator just for the PICAXE?
________

BeanieBots · Oct 10, 2010

If you use the regulator, you can dispense with the 100uF cap but I would still strongly recommend using 100nF close to the PICAXE.
The PIR should be happy running from 5v and if you run the PICAXE and PIR from the same voltage, you would not need a resistor between them. Also, you would not need the potential divider resisitors and the circuit (depending on chosen regulator) will probably use less power.

You will need caps for the regulator but refer to its datasheet for specifics.
It needs to be an LDO type to work using a 6v input voltage.

Michael 2727 · Oct 11, 2010

As mentioned a Voltage Divider Will / Can work but it would be a last resort for most
applications due to the usually low current limit capability.

3 x AAA Cells work fine for a lot of stuff, but again limited current for extended periods.

A Regulator would be the best option, though they can waste a lot of power in
some apps, LDOs can sometimes be better here.

I have recently been using a Lantern Battery (4R25X) 6V with a single Power Diode
which gives you around 5.4V to 5.6V to work with and up to 1A or so in current.
( there are many variations of 6V lantern Battery, UK, Euro, US, AU can differ )
Mine is square, double the height as width, with 2 spring terminals on top.

A Signal Diode 1N4148 or 914 don't drop as much voltage and 60mA to 100mA current limit.
A Schottky gives much the same or less V-Drop but up to 1A current.

Both the signal and schottky are not much good to you in this application,
But a single Power Diode or 2 if that's what it takes, may solve the problem.

Some diodes these days do not have a full 0.6V drop so 2 may be needed, it will also
depend on your load required.

2c worth.

Dippy · Oct 11, 2010

Michael, I'm not sure about "sometimes" - I don't really think you have any other choice than LDOs.

And a PD as a power supply is very wasteful of power!

Mind you, some LDO claims I've seen haven't been very LDO, but it's all relative and depends on a number of parameters.

I'd sooner drop V with a diode rather than a PD, but if you have access to the BIG Distributors then you will find a suitable regulator for this App for the massive cost of 50p.
This was mentioned in recent thread for 6V to 5V, where you can get LDORegs with Dropout of 100mV.

And remember, that the voltage drop of a diode (or any semi junction) is current related.
Most people think it's 0.6V full-stop (and that Zeners are on-off at Zv) - sadly most people don't read the specs

Anyway, this is going round in circles. I'm going to wait for GEditor to try out the circuit ASSUMING he has followed the advice given.

Coffee Break... SOME IDEAS ... FOOD FOR THOUGHT.

Nasty old PD version:-
Optional Cap for PICAXE includes 100Uf electrolytic to act as a reservoir.
The 100nF Ceramic can be lower - this was simply an example.
Optional Cap by Piezo only needed if Piezo electrically noisy (some are - be warned!). Value 100nF may help.
REMEMBER (I shall say this ONLY ONCE!!) : Electrical noise and/or transients getting to PICAXE or LCD can really mess things up! In previous designs I've had to decouple LCD too in noisy circuits.

Lovely LDO Reg version:-

Do a search in Farnell. Regulators ---> LDO and then select values. 50p should cover it. Don't forget the correct VALUE and TYPE of cpacitors.
ALWAYS... ALWAYS read the Data Sheet and any App Notes. Tell your teacher to do that too.

END // Spoonfeed.

If you read this and all the above posts then you should be able to come back with a working circuit. If you don't read and absorb, then good luck

TinyPIC is great except for that crap Recaptcha check thing which is rubbish - obviously had a good salesman!

geditor · Oct 11, 2010

Hi,
I couldn't get the components today because my teacher was ill but hopefully I will be able to get them tomorrow and try it out.

However, I now know that I will be using a voltage regulator as everyone has been advising too.

Thanks for all your help. I will be getting the components tomorrow.
________

BeanieBots · Oct 11, 2010

Don't forget to get the DATASHEETs as well.
You will need them (particularly for the regulator) to get the values for its decoupling caps and to know for sure if it is suitable for your application.
The old dinosaur 7805 will NOT be a suitable choice if you want to run off 6v.

geditor · Oct 13, 2010

Hi,
I ended up not doing any of that... I sure it would of worked but I asked someone about the PICAXE voltage and he said that 5V is recommended but if I use 6V is still could be okay but is just risky and could blow the PICAXE. I took the risk, and didn't bother with any capacitors and everything works fine now.

I might need that capacitors or voltage regulator when I build it further and add a solenoid for a combined safe but that's for later. Thanks for all your help!!!!!

________
Rhode island medical marijuana dispensaries

eclectic · Oct 13, 2010

geditor said:
Hi,
I ended up not doing any of that... I sure it would of worked but I asked someone about the PICAXE voltage and he said that 5V is recommended but if I use 6V is still could be okay but is just risky and could blow the PICAXE. I took the risk, and didn't bother with any capacitors and everything works fine now.

I might need that capacitors or voltage regulator when I build it further and add a solenoid for a combined safe but that's for later. Thanks for all your help!!!!!

"someone" ?

Well, it's YOUR picaxe and your money, but,
how about asking some of the experts HERE?
(No, I'm not an expert)

e

BeanieBots · Oct 13, 2010

Not wise but it's your PICAXE and your choice.
Please don't complain WHEN it fails.
Let us know how it works out when you add the solenoids!

BeanieBots · Oct 13, 2010

From page 331 of the manufacturer's datasheet
http://ww1.microchip.com/downloads/en/DeviceDoc/41365D.pdf

25.0 ELECTRICAL SPECIFICATIONS
Absolute Maximum Ratings(&#8224
Ambient temperature under bias....................................................................................................... -40°C to +125°C
Storage temperature ........................................................................................................................ -65°C to +150°C
Voltage on VDD with respect to VSS, PIC18F1XK22 ........................................................................... -0.3V to +6.0V
Voltage on VDD with respect to VSS, PIC18LF1XK22 ......................................................................... -0.3V to +4.0V
Voltage on MCLR with respect to Vss ................................................................................................. -0.3V to +9.0V
Voltage on all other pins with respect to VSS ........................................................................... -0.3V to (VDD + 0.3V)
Total power dissipation(1) ...............................................................................................................................800 mW
Maximum current out of VSS pin ...................................................................................................................... 95 mA
Maximum current into VDD pin ......................................................................................................................... 95 mA
Clamp current, IK (VPIN < 0 or VPIN > VDD)20 mA
Maximum output current sunk by any I/O pin.................................................................................................... 25 mA
Maximum output current sourced by any I/O pin .............................................................................................. 25 mA
Maximum current sunk by all ports ................................................................................................................... 90 mA
Maximum current sourced by all ports ............................................................................................................. 90 mA
Note 1: Power dissipation is calculated as follows: PDIS = VDD x {IDD –  IOH} +  {(VDD – VOH) x IOH} + (VOl x
IOL).
† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the device at those or any other conditions above those
indicated in the operation listings of this specification is not implied. Exposure above maximum rating conditions for
extended periods may affect device reliability.

What is your 6v supply?
4 X 1.5v maybe?
Have you measured it? What was the ACTUAL voltage?

geditor · Oct 16, 2010

BeanieBots said:
Not wise but it's your PICAXE and your choice.
Please don't complain WHEN it fails.
Let us know how it works out when you add the solenoids!

You seem pretty sure its going to fail. I'm not going to a solenoid in and build a safe any more... I'm going to keep the circuit simple. Thanks for your help.
________

Dippy · Oct 16, 2010

Wise. In our Quantum World, everything has a statistical probability of happening in a certain amount of time.
And that includes failure in an electronic device.

Manufacturers provide data after they have tested (in most cases anyway haha).
It is there to tell you that if you go beyond the Maximum ratings you are 'pushing your luck' and/or that the device may be out of spec.
In certain cases a PIC can be partly damaged but not be a complete melt-down failure.

It is ALWAYS recommended that you read the relevant Microchip PIC Data Sheet for your chosen PICAXE.
Play safe - keep within the specifications given.

BeanieBots · Oct 16, 2010

geditor said:
You seem pretty sure its going to fail.

I'd bet a PICAXE on it, especially if you add the solenoids.
How about that supply of yours. What IS the ACTUAL voltage?

If all you want to do is switch a few LEDs on and off, then you can probably 'get away' without the decoupling caps too but it should a reflex action to add them just like putting on a seat belt when you get in a car. It should be so instinctive that you don't even think about it, your hand & pen just automatically draw them on the circuit.

geditor · Oct 17, 2010

Yeah, you're both probably right in what your saying but my circuit is supposed to be relatively simple - I just don't want to make it too complicated which is why I'm leaving out the solenoid and safe function as I may have to use the voltage regulator along with all the decoupling capacitors.

In any case I took advice and used the capacitor across the V+ and 0V on the PICAXE.

I read a few of the datasheet and project sheets on the revolution education website and found that some of the PICAXE's are powered by 6V. I'm going to look at the PIC datasheet for the 20X2 now but honestly, I don't have many worries at the moment.

I might just test the solenoid to see if what you guys said will happen (failure).

Thanks for all your advice anyway.
________

PICAXE 20X2; an output from PIR causes PICAXE to reset (or goto to beginning)-Fix it?

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