Hello, so i am now working on the filterwheel DRV8825 and just want to clarify something so it says in the pdf " The Nano typically will be
powered from 12VDC and be connected to the computer via a mini-USB cable" so to clarify if i only have the 12v connected up without the usb hooked up to the nano i will not have any power to my nano ? because the only way i can get my nano to power is to plug it in the USB if i unplug the USB the nano powers off while the 12v is still powered , is this correct ?
Thanks
Tim
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to clarify if i only have the 12v connected up without the usb hooked up to the nano i will not have any power to my nano ?
No. the nano will get its power from 12v
only way i can get my nano to power is to plug it in the USB
No. it works off 12V
if i unplug the USB the nano powers off while the 12v is still powered
No, it still works off 12v, but you cant send it any commands - because we use the usb for "talking" to the controller and the app on the computer
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First, good question
Second, apologies for long answer.
All the myxxxx projects are designed for usage off 12V. The USB cable provides the connection interface for sending commands and getting responses.
This project uses the 12v dc to power the nano and stepper motor, so if you do not have 12v power to the controller, the motor does not move.
USB connections typically cannot provide enough "current" to power the nano. sensors and motor. So, the circuits are designed to work of 12v dc, but you need to "talk" to the controller to tell it to move to another filter etc (so we use the USB to do that "talking")
12v comes into the controller, goes through the 1N5408 diode, then goes direct to the DRV8825 chip VMOT pin - and also goes as input to the LM7xxxx regulator. The output of the regulator does through another diode D1 HER208 (the diodes help prevent damage if the 12v got connected the wrong way round) and then to the VIN pin of the Nano.
The rule for VIn is that the voltage on the VIn must be around 1-2v higher than the 5V from USB.
We have 12v going into the controller, then through diode D1 - the diode consumes about 1v - 1.3v, meaning the voltage going in = 12v and the other side (12-1v) = 11V which then goes to the LM regulator whose output is 9V.
9V going into D1 HER208 drops another 1v so what is going to VIN of the nano is (9v -1v) = 8v
The rule is if VIn is > USB (5v+1v) (vin we worked out to be 8v,
VIN = 8V, USB = 5V
so the nano will use the power from the 12V supply and not the USB 5V cable.
This is really important, because if the project supports bluetooth or WiFi it means we do not need a USB cable (because bluetooth or WiFi is used to "talk") and the controller functions fine.
Regards
R
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Ok that helps a lot and now time to trouble shoot because i plug in the 12v without the usb and i get no light lighting up on my nano unless the usb is plugged in so time to figure out why and m what is wrong .
Thanks !
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hello, so i am now working on the filterwheel DRV8825 and just want to clarify something so it says in the pdf " The Nano typically will be
powered from 12VDC and be connected to the computer via a mini-USB cable" so to clarify if i only have the 12v connected up without the usb hooked up to the nano i will not have any power to my nano ? because the only way i can get my nano to power is to plug it in the USB if i unplug the USB the nano powers off while the 12v is still powered , is this correct ?
Thanks
Tim
to clarify if i only have the 12v connected up without the usb hooked up to the nano i will not have any power to my nano ?
No. the nano will get its power from 12v
only way i can get my nano to power is to plug it in the USB
No. it works off 12V
if i unplug the USB the nano powers off while the 12v is still powered
No, it still works off 12v, but you cant send it any commands - because we use the usb for "talking" to the controller and the app on the computer
First, good question
Second, apologies for long answer.
All the myxxxx projects are designed for usage off 12V. The USB cable provides the connection interface for sending commands and getting responses.
This project uses the 12v dc to power the nano and stepper motor, so if you do not have 12v power to the controller, the motor does not move.
USB connections typically cannot provide enough "current" to power the nano. sensors and motor. So, the circuits are designed to work of 12v dc, but you need to "talk" to the controller to tell it to move to another filter etc (so we use the USB to do that "talking")
12v comes into the controller, goes through the 1N5408 diode, then goes direct to the DRV8825 chip VMOT pin - and also goes as input to the LM7xxxx regulator. The output of the regulator does through another diode D1 HER208 (the diodes help prevent damage if the 12v got connected the wrong way round) and then to the VIN pin of the Nano.
The rule for VIn is that the voltage on the VIn must be around 1-2v higher than the 5V from USB.
We have 12v going into the controller, then through diode D1 - the diode consumes about 1v - 1.3v, meaning the voltage going in = 12v and the other side (12-1v) = 11V which then goes to the LM regulator whose output is 9V.
9V going into D1 HER208 drops another 1v so what is going to VIN of the nano is (9v -1v) = 8v
The rule is if VIn is > USB (5v+1v) (vin we worked out to be 8v,
VIN = 8V, USB = 5V
so the nano will use the power from the 12V supply and not the USB 5V cable.
This is really important, because if the project supports bluetooth or WiFi it means we do not need a USB cable (because bluetooth or WiFi is used to "talk") and the controller functions fine.
Regards
R
Ok that helps a lot and now time to trouble shoot because i plug in the 12v without the usb and i get no light lighting up on my nano unless the usb is plugged in so time to figure out why and m what is wrong .
Thanks !