Connecting pwr ground to positive


choco107@...
 

Hi, i stupidly connected the opposite power wires by mistake. I connected power to ground and ground to power. When I power up onstep I get red power lights on the modules but no green light on the stm32 and the wemos blinks blue for a split second when powering on then nothing . Did I blow something ?. What would be the first thing to go?? 


Mike Ahner
 

If it's a Blue Pill kit board, it doesn't have protection for that scenario and probably the voltage regulator is blown. It may be shorted or putting out low power. It's soldered but you can cut the 4 pins and then clean out the holes.

I suggest removing all the pluggable modules and checking the voltages on the board starting with the voltage regulator. Check the power pins on each modules socket for correct voltage. If the voltage is 5 vdc everywhere, then plug in one module at a time and check the voltage each time. 

If the voltage is excessively above 5vdc, one or more pluggable modules are probably bad. The WEMos can be tested by reflashing it, the CP2012 USB part can be tested by connecting to a USB port and see if it's recognized, but it's not powered from the Blue Pill PCB, just from USB.

You must have the EEPROM which is in the DS3231 chip or OnStep won't run at all.

If the voltages are correct, you should be able to replace the STM32, if not, then probably one or more capacitors are blown. These often swell up or even pop the top open.

Just be methodical and measure, measure, measure. Of course, depending on your resources I understand, but none of the parts for the Blue Pill are expensive. You may have to wait a little though.

Good luck choco!


Mike Ahner
 

On Mon, Nov 2, 2020 at 10:27 PM, Mike Ahner wrote:
If the voltage is excessively above 5vdc, one or more pluggable modules are probably bad.
I didn't make clear, if the voltage is above or below 5vdc & you can't readjust the voltage to 5vdc, then you'll need to replace the voltage regulator.

If the voltage is low and can't be adjusted, there maybe a short on the pcb, so you can also just cut the output pin that feeds the Blue Pill board and see if the voltage can be adjusted again. Most of these kinds of voltage regulators "crowbar" on overload, that is they shutdown or limit the voltage & current if there's a short.

But the module itself may be damaged. 


choco107@...
 

Thank you for the lengthy reply. So took all the modules out. Tested the voltage reg, and it was at 5v. Checked all the power pins on the board and all where 5v. Plugged each module in one by one all seems fine. So I'd imagine it's the stm32? The power led is coming on but no green led on the STM32.


 

Lesson Learned:  Buy spare parts--sooner or later, you'll need them.  (Don't ask me how I know!)


Dave Schwartz
 

If you get the power LED on the STM32 but not the tracking LED then the problem is most likely the DS3231 (ZS-0941) module, specifically the EEPROM component. If that is not responding, OnStep will freeze early in the startup process on the Blue Pill. Try flashing and running some of the utilities in the files area, like the eeprom wipe or i2cscanner.

On 2020-11-03 5:20 a.m., choco107@... wrote:

Thank you for the lengthy reply. So took all the modules out. Tested the voltage reg, and it was at 5v. Checked all the power pins on the board and all where 5v. Plugged each module in one by one all seems fine. So I'd imagine it's the stm32? The power led is coming on but no green led on the STM32.


Dave Schwartz
 

If OnStep is to the point of responding to serial commands, it is past the point where it would have frozen if the eeprom had not been working.

The 'Tracking enable' command is :Te#

Most of the commands are documented at https://onstep.groups.io/g/main/wiki/23755

On 2020-11-03 2:51 p.m., choco107@... wrote:
Ok so I connected up the controller went into serial monitor and entered :GVP# and it came back with onstep. Is there a way through serial monitor to start auto tracking ? So the tracking led will flash. I'm thinking it could be the eeprom alright. I checked the batt voltage and it fine 3.3v


choco107@...
 

Ok so I went into serial monitor and input and it came back as onstep
I put in :A1#  to get the led blinking and that worked fine. So looks like it may be working . How come the green led on the STM32 is not illuminated? Also nothing for the wemos so I'm going to look into that now 


choco107@...
 

Ok so back at this after a long while. Can't seem to get the motors to move , buzz , nothing. Onstep seems to work fine as you can see form the video clip. I have BLK on pin1, grn 2, blue 3 and red 4. Those pairs I checked by holding pairs together and turning the motor by hand. Wiring seems fine. Vref is set to .90. .9a motor , lv8792 with r220. 

Is there anything else i can check. ?


kevin
 

Difficult to tell from the video but you seem to have a lv8792  driver in AX2 , it looks like may be wrong way round. no driver in AZ1 and what driver do you have in AX4, that may be wrong way round as well.  AX4 isn't plugged int0 motor but by putting in them the wrong way round could stop the working partially or totally when put in properly ?
A still photo of just the board may help.


choco107@...
 

Pic of the board with original drivers  I had only one new driver in for testing. 


kevin
 

I think the LV drivers are the wrong way round. what is the AX4 driver?
There was a long thread about this a few weeks back this is the last one


Khalid Baheyeldin
 

On Fri, Jan 7, 2022 at 04:11 PM, kevin wrote:
I think the LV drivers are the wrong way round.
Check if your LV8729 has black colored pins on one side, and another color on the other side.
If they are, then the black side must be towards the 4 pin plug for the motors.
If they are not, then you need to figure out which way is towards the motors, and which way towards
the STM32.

what is the AX4 driver?
Focuser.


choco107@...
 

I just checked the blue side pins were towards the motor plugs. So they were the wrong way round. I take it there fried now ? 


kevin
 

I think the outcome of that thread was that at least some survived,  i can't remember best read that thread.
also check the AX4 driver, i can't tell what it is.
The issue is there is no fixed way of telling which way round they go. you really have to be very careful with them. i have to continuity check the 2 earth pins on the motor side to be sure. Some drivers are supplied with all black pins, some with pins unsoldered others have no markings. the LV drivers can have the chip on the top or bottom of the board. some have the setting resistor one end, soome the other. some of the drivers have the vcc pin as an input others have it as an output.


choco107@...
 

The other driver(focus) is a dvr8825


kevin
 

That looks the correct way round for that position, does that work for the focuser ? check the Wiki for what you do for the jumpers on all the drivers.
if your other drivers are  damaged you should be able to use the DVR8825 to check out the other sockets, remember rotate AX2,  are still working and the Bluepill is OK.


choco107@...
 

I had a look at the other thread. I have one spare lv827 that wasn't plugged into the board. I'll reflash the stm32 and try the new driver turned the right way tomorrow and see what happens 


choco107@...
 

Ok still no movement. I swapped the drivers the right way round and re flashed the stm32. Nothing

Got a new stm32 and flashed it. Got a new lv2927 the right way around. Still nothing. I got back the green led on the stm32 which must of been blown on the old board. Tried another ethernet cable. Nothing.

When I have it connected up and slew the telescope in stellarium. The power supply is only showing .069 A draw ?? At 12v 





Ken Hunter
 

The power supply will not give you reliable current indications of the stepper drive.
The drive signal is not DC, it is a square wave at a very high rate so the power supply will only show an approximation of the Average current.

That being said, you should be able to see more average current than that! Measure the VMOT at the Driver VMOT pin to make sure that there is the correct voltage there also since you are using the LV8729, the EN pin should be logic LOW when the motors are supposed to be moving.