Hi all, I wonder if anybody can help me. I think I've just fried my board and I need to find another approach before I do the same again.
Here's what I'm trying to achieve:
I have stripped the components from an Epson flatbed scanner. I am trying to reverse engineer the parts to find out some information about the scanning operation. Amongst the components is a stepper motor (bipolar (4 leads)). I want to find out how many steps the motor makes during the scanning operation. In order to do this I wrote a short program which counts the number of pulses sent to the motor from the board it is connected to. Instead of connecting the board to the motor, I have connected to them to 4 input pins on my arduino board. When I ran the program, my computor actually shut down - I think it shorted or something. Now I am getting this error when I try an upload a program: avrdude: stk500_getsync(): not in sync: resp=0x00
So I think I have broken to board.
On the basis that I have broken the board, how can I make this work another way? Do I need to weaken the current before it reaches the pins or did I not ground it? As I say I only used one wire.
aprior4:
On the basis that I have broken the board, how can I make this work another way? Do I need to weaken the current before it reaches the pins or did I not ground it? As I say I only used one wire.
It was probably the lack of grounding that killed it. Always connect grounds.
Did you measure the supply voltage on that stepper before hooking the Arduino to it? I've scavenged parts from several Epson & Canon multifunctions & scanners so I just went and checked out the steppers. Unfortunately I haven't marked them with where I pulled each from, but voltages marked include 6, 12, 14 and 24V so nothing that an Arduino is going to be happy with.
So first things first, it is possible you've fried the ATmega328. If it's a regular Uno they're socketed and the part isn't expensive, and you can buy them readily with the Arduino bootloader already on it - so it would be as simple as pulling the cooked one and pressing the 'raw' one into the socket.
Before you fry up the next one measure the voltage of the signal you're going to be monitoring. Arduino Uno (if that's the variant of Arduino you're using) is interested in 5V maximum. That means, yes, you'll be wanting to reduce the signal voltage. That can be done with a voltage divider - a simple circuit of two resistors (or a potentiometer if you have one).
And you'll always want to connect the grounds.
Do you have a multimeter to measure that signal pulse voltage with?
Hi everyone, thanks for the helpful replies. I will pop out to buy a multimeter now and measure the voltage. I've looked up the tech specs for the motor. There is a scarcity of info. All I know is that the motor is rated at 5.8 ohms.
I'm afraid I must ask an ridiculously simple question which will reveal that I am a complete newbie: How can I ground the wires? On the epson board I've got 4 pins that should be connected to the motor. Are two of them + and two of them -? Is there something I need to connect to the gnd pin on the arduino board?
A stepper motor has a number of coil. By activating the different coils in a rotating way, the stepper starts turning.
Sometimes one wire of a coil is connected to ground, but not always.
Perhaps the ground of a connector (parallel or USB) is the ground of the device.
Are you sure you want to continue with this project ?
If you use the Arduino with an lcd display and with a temperature sensor, a humidity sensor, and a barometer, you have the same amount of fun (I would) and less change for a fried Arduino.
Hi Erdin, that sounds like a reasonable suggestion. thanks for your help. For connecting the GND of the Arduino to the GND of the USB - there is no obvious place for me to make this connection. As I'm sure you know the USB protocol consists of DATA+, DATA-, +5V and GND. The Female USB port is soldered onto the chip. Are you suggesting that I solder the GND from the Arduino to the GND pin on the underside of the board? Obviously you dont know the Epson board I'm working on...
Yes, that was my suggestion....
Or perhaps you can see a voltage regulator, like a 7805 or so. You should find a ground there.
So - If I were to connect the GND of the Arduino to the GND of the Female USB on the EPSON board:
this would mean that there are two connections making use of this GND pin. Can I do this?
Suppose the output signal of the EPSON board is 4V.
That 4V is 4V above the ground level. Otherwise it won't be 4V.
The Arduino has to read it, but it can only read it if the input of the Arduino is higher than the ground of the Arduino. So the ground should be connected to the ground that the 4V belongs to.
It is like using a multimeter. You have a red and black test lead. You can't read the voltage of a battery with only the red test lead to the (+) of the battery. You must also hold the black test lead to the (-). That black test lead is the ground.
And so this operation can be as simple as soldering a wire onto GND pin on the underside of the EPSON board? Sorry I hope you understand that I need to be real careful because I'm trying to modify this scanner and I paid some money for it. It would be a shame if I broke the parts.
Yes, you can use a multimeter to test it.
You could use a safety resistor of 100 ohm between the grounds if you are not sure. I do that now and then.
The thing is, they could already be connected.
If the EPSON board is connected to the PC, and the Arduino to the PC, the grounds are already connected via the PC. You have to make the ground connecton anyway, in case the EPSON board or Arduino is not connected to the PC.
