The 12v led turns on when I have just the usb plugged into the arduino. Ive looked for something I have connected wrong but don't see anything. If I plug in the 12v and turn on (with the usb connected) the led gets brighter. Any thoughts on what I have wrong? I would think the 12v led would only come on when I have the 12v switch on.
Mark
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Nothing wrong, is normal, should not be but it is, belive the culprit is the Arduino VIN circuitry on the Arduino itself. We could put a diode in line to VIN after the regulator but hey there are enough components already. Don't worry, it won't blow up.
Cheers
Robert
PS I kinda like it even though it should not be happening! Tells me if I have 12V on!
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Actually here is a very simple test to try - use a prewired 5V LED (or a 5V led with a series 470ohm resistor), plug -ve lead into GND and +ve lead into VIN, then connect up the arduino via USB - aint no issue with our circuits - issue is with Arduino on board logic releated to VIN
Cheers
Robert
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Thanks. I have it all hooked and just need to adjust the amperage to the stepper and finish setting it up and calibration. With a little luck I'll have it on the scope by tomorrow. Thanks for putting this up on the web to do!
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
One other thing. Is there a way to reduce the brightness of the LCD backlight and of the red power led. I'm concerned that they will be really bright out in the observing field.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi Mark
First the RED power LED. All LED's have a point where they turn on. For the 12V LED I do not know if you are using a pre-wired LED or a series resistor to limit the current.
You can experiment on a bread-board with different values of for a series resistor (a resistor wired in series with the LED - one wire of led to positive, the other wire of the LED to a resistor, the other end of the resistor to ground. So try starting with something like 470 ohms and slowly increase till the brightness goes down a little. Or you can try red nail varish and just paint over the led surface to make it dimmer.....
Next the LCD backlight,with an I2C board this is probably not adjustable, the small blue pot on most LCD-I2C boards controls the characters brightness. So not much you can do about it unless you hardware hack the I2C board on the back of the LCD.
Looking at the back of the LCD, the I2C backpot has a blue pot as well as a jumper across two pins. This is the backlight jumper - if you remove it the backlight will alwaysbe off.
I'm not sure of the following, the idea I just thought about so not sure if it will work. You could try using a resistor across the two pins instead of the jumper - but I suspect it would have to be a low resistance value like 5 or 10 or 15 or 21 ohms would be best to start with. This might change the backlight brightness - never tried it but its worth a try. If it doesnt work it doesnt work
Cheers
Robert
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Ok an update.
I have just tried it by using a 10K pot wired direct across those 2 pins - remove the jumper and replace it wirth 10k trimpot - use outside wire and center wire - and yes it works exceedingly well...
On the DRV8825 the specs I found said to set the reference voltage at current limit/2. For the 17HS13-0404S-PG17 it says rated current is 0.4 amps. So would the reference voltage be set at 0.2 volts? Is that correct. The pdf says 2.1 volts
Last edit: Mark Woolridge 2017-02-19
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
If you have a multimeter, insert multimeter into one coil path of the stepper and set to measure current, the correct method is to set the stepper motor to full steps, coil power on. Then measure current and set pot to 70% of coil current (70% of 400mA = 280mA).
I prefer to set manually as outlined on page31 of pdf.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I have changed all the PDF's so there is one consistent method used in all the docs. There is a difference on setting it via voltage depending on if its DRV8825, EasyDriver etc, hence the confusion. Setting it by measuring current in one coil is preferred.
Regards
Robert
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Robert,
I have the focuser up and running. I used it last Saturday and it worked like a champ. Thanks for all your hard work on this. One question I have is how you can disable the home switch. Even though the code has it disabled if I select the home button in the window program my focuser starting to move towards zero. I don't have a home switch installed either. I am using the DRV8825 HW203 board. Also in the windows program is it possible to lock or put a confirmation y/n on the set position and set max steps. It's easy to accidently hit the set position instead of goto and thus change the current controllers postion by accident. Then you have to set it up again if you don't remember the last location. Again thanks for the hard work.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi Mark
The arduino firmware code has the home position switch portion disabled. So when you select HOME what will happen is it will go to position 0 and stop. In focuser terminology, HOME in this instance is always assumed to be position 0.
For the set position and set max steps I can add a confirm dialog box to these. The default would be OFF, and you can enable this via the extra settings form before connecting to the focuser. The state would be remembered by the app. So let me code it and I will post here, should not take too long, and then you can try it and let me know.
The 12v led turns on when I have just the usb plugged into the arduino. Ive looked for something I have connected wrong but don't see anything. If I plug in the 12v and turn on (with the usb connected) the led gets brighter. Any thoughts on what I have wrong? I would think the 12v led would only come on when I have the 12v switch on.
Mark
Nothing wrong, is normal, should not be but it is, belive the culprit is the Arduino VIN circuitry on the Arduino itself. We could put a diode in line to VIN after the regulator but hey there are enough components already. Don't worry, it won't blow up.
Cheers
Robert
PS I kinda like it even though it should not be happening! Tells me if I have 12V on!
Actually here is a very simple test to try - use a prewired 5V LED (or a 5V led with a series 470ohm resistor), plug -ve lead into GND and +ve lead into VIN, then connect up the arduino via USB - aint no issue with our circuits - issue is with Arduino on board logic releated to VIN
Cheers
Robert
Thanks. I have it all hooked and just need to adjust the amperage to the stepper and finish setting it up and calibration. With a little luck I'll have it on the scope by tomorrow. Thanks for putting this up on the web to do!
One other thing. Is there a way to reduce the brightness of the LCD backlight and of the red power led. I'm concerned that they will be really bright out in the observing field.
Hi Mark
First the RED power LED. All LED's have a point where they turn on. For the 12V LED I do not know if you are using a pre-wired LED or a series resistor to limit the current.
You can experiment on a bread-board with different values of for a series resistor (a resistor wired in series with the LED - one wire of led to positive, the other wire of the LED to a resistor, the other end of the resistor to ground. So try starting with something like 470 ohms and slowly increase till the brightness goes down a little. Or you can try red nail varish and just paint over the led surface to make it dimmer.....
Next the LCD backlight,with an I2C board this is probably not adjustable, the small blue pot on most LCD-I2C boards controls the characters brightness. So not much you can do about it unless you hardware hack the I2C board on the back of the LCD.
Looking at the back of the LCD, the I2C backpot has a blue pot as well as a jumper across two pins. This is the backlight jumper - if you remove it the backlight will alwaysbe off.
I'm not sure of the following, the idea I just thought about so not sure if it will work. You could try using a resistor across the two pins instead of the jumper - but I suspect it would have to be a low resistance value like 5 or 10 or 15 or 21 ohms would be best to start with. This might change the backlight brightness - never tried it but its worth a try. If it doesnt work it doesnt work
Cheers
Robert
Ok an update.
I have just tried it by using a 10K pot wired direct across those 2 pins - remove the jumper and replace it wirth 10k trimpot - use outside wire and center wire - and yes it works exceedingly well...
Robert
Last edit: brownrb 2017-02-18
On the DRV8825 the specs I found said to set the reference voltage at current limit/2. For the 17HS13-0404S-PG17 it says rated current is 0.4 amps. So would the reference voltage be set at 0.2 volts? Is that correct. The pdf says 2.1 volts
Last edit: Mark Woolridge 2017-02-19
Never connect/disconnect stepper when power is on
If you have a multimeter, insert multimeter into one coil path of the stepper and set to measure current, the correct method is to set the stepper motor to full steps, coil power on. Then measure current and set pot to 70% of coil current (70% of 400mA = 280mA).
I prefer to set manually as outlined on page31 of pdf.
Hi Mark
I have changed all the PDF's so there is one consistent method used in all the docs. There is a difference on setting it via voltage depending on if its DRV8825, EasyDriver etc, hence the confusion. Setting it by measuring current in one coil is preferred.
Regards
Robert
Robert,
I have the focuser up and running. I used it last Saturday and it worked like a champ. Thanks for all your hard work on this. One question I have is how you can disable the home switch. Even though the code has it disabled if I select the home button in the window program my focuser starting to move towards zero. I don't have a home switch installed either. I am using the DRV8825 HW203 board. Also in the windows program is it possible to lock or put a confirmation y/n on the set position and set max steps. It's easy to accidently hit the set position instead of goto and thus change the current controllers postion by accident. Then you have to set it up again if you don't remember the last location. Again thanks for the hard work.
Hi Mark
The arduino firmware code has the home position switch portion disabled. So when you select HOME what will happen is it will go to position 0 and stop. In focuser terminology, HOME in this instance is always assumed to be position 0.
For the set position and set max steps I can add a confirm dialog box to these. The default would be OFF, and you can enable this via the extra settings form before connecting to the focuser. The state would be remembered by the app. So let me code it and I will post here, should not take too long, and then you can try it and let me know.
Cheers
Robert
Last edit: brownrb 2017-02-28
Thanks Robert!