Download cable

Hi

The program runs properly when the download cable is connected and computer on, but as soon as it is disconnected or the computer is turned off, the program does its own thing.

I measured the voltage on the serial stereo plug (see attachment). Is this normal?

regards
michael
 

Attachments

SAborn

Senior Member
I would think you are missing a earth wire (v-)on your board some where and the circuit is earthing through the computer.

Check your circuit wiring, and a drawn schematic of the circuit would be more helpful than the plug drawing.
 

inglewoodpete

Senior Member
From my experience, I'd say that you don't have the 10k + 22k download resistors connecting properly between the Serial In pin and the 0v common. They must always be in place to get the PICAXE to run correctly.

Have a read up on the minimum operating circuit in Manual 1 - Getting Started.
 

westaust55

Moderator
From my experience, I'd say that you don't have the 10k + 22k download resistors connecting properly between the Serial In pin and the 0v common. They must always be in place to get the PICAXE to run correctly.

Have a read up on the minimum operating circuit in Manual 1 - Getting Started.
In reality, only the 10 kOhm pull down resistor MUST always be part of the circuit.

However it will typically be a lot easier to work with the project/circuit to re-program at any time, if the 22 kOhm resistor is also fitted permanently
 

inglewoodpete

Senior Member
In reality, only the 10 kOhm pull down resistor MUST always be part of the circuit.

However it will typically be a lot easier to work with the project/circuit to re-program at any time, if the 22 kOhm resistor is also fitted permanently
In this case, the 22k resistor must be fitted. Michael is using an RS232 cable (10.2 volts at the programming plug)
 

westaust55

Moderator
Okay to express it another way

When NOT programming the 10 k Ohm resistor is ALWAYS required otherwise the PICAXE chip will NOT operate, but the 22 kOhm resistor is optional.

When programming the PICAXE chip or when the programming cable is still conencted to the PICAXE chip, the 22 kOhm resistor is also required.
 

Dippy

Moderator
Probably a wiring fault.
Post your schematic and tell us what sort of jack socket you are using and how you've connected it.
 

BeanieBots

Moderator
When NOT programming the 10 k Ohm resistor is ALWAYS required otherwise the PICAXE chip will NOT operate, but the 22 kOhm resistor is optional.
Just to make it even more clear, you can't just remove the 22k, the 10k must be connected to the serin pin (to pull it low) so the 22k can be a link.
 

BeanieBots

Moderator
Now I'm confused.:confused:
Is this a download problem, erratic behaviour problem or software issue?
Please re-state very clearly what your issue is and the circumstances that lead up to it.
 
in the beginning I could not download to the sd21. The result was because I added extra resistors(10 @ 22k) to the download circuit. I removed these resistors and it worked.( The resistors are already on the sd21 board)

When I download the program, the crane runs fine. It is activated by a switch. If I unplug the stereo connection, the crane keeps repeating ( the switch has no effect) . It also runs a little more erratic.

If I plug the serial plug back in, once again, runs fine. If I leave the plug in and turn off the computer, it goes haywire, until I turn the computer back on, then once again is fine
 

Dippy

Moderator
This behaviour when unplugging is odd.

What happens (when unplugged) if you put a 10K res from Rx pin to ground?
I don't have schematic of that board, so guessing a bit here.

Have you damaged the board with your experimenting and soldering?
After looking between these two threads I'm unsure as to the state of the board and things soldered to it. All a bit confusing.

Is the PICAXE reset pin pulled high properly?
 

Technical

Technical Support
Staff member
It is more likely to be the wiring of the switch that is wrong than the PICAXE circuit, as that is predefined on the SD21.

How exactly have you connected the switch to the SD21?

In the cable inserted/computer switched off scenario you could be getting any kind of random signal down the cable. Download cables should generally only be in place when required, remove after development is finished.
 
I have uploaded a picture of how the setup looks.

I have tested it with different power supplies.
There has been no soldering on the board.
The 2 switches that activate the 2 servo programs are currently wires that I switch to high by placing them on a 5v supply. I am using input0 and input1.

I have not managed to find a scematic of the sd21, but maybe all the input pins are floating. Might have to find the magnifing glass and look at the board.

When I get a chance I will play around with it some more

Thanks for the quick replies

michael
 

Attachments

hippy

Technical Support
Staff member
I can't see anything wrong with the connection but it does look a bit messy on the veroboard ( green wire to socket ) so could be worth trying with a new socket. If given the chance I'd suggest using different colour wires so green goes to 0V.

Also, remove the masking tape label on the board as RX/TX/-/GND is wrong and just adds to the confusion.

The AXE031 (SD21) connector is, from top to bottom - TX / RX / - / 0V

The 3.5mm jack with pins down, plug to top, from left to right - 0V / TX / RX
 
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