Show Posts
Pages: [1] 2 3 ... 9
1  Using Arduino / General Electronics / Re: Why is the cascade output on shift registers called QH'? on: August 07, 2013, 03:04:02 pm
Ah I see, so the prime mark simply indicates that it is not the same point as the regular QH. I thought it meant the inverse. That makes things more clear.
2  Using Arduino / General Electronics / Why is the cascade output on shift registers called QH'? on: August 07, 2013, 02:09:01 pm
I want to make a tutorial on how shift registers and SPI work, but I am having trouble understanding it myself. I know how to chain shift registers using the last output pin, but in this logic diagram, why is the cascade output on the right called QH' and not just QH? Don't the two inverters make it QH again? Here is another logic diagram made by another company, same chip, but it is even more confusing.
3  Using Arduino / LEDs and Multiplexing / Re: Increasing Brightness Linearly on: July 27, 2013, 08:17:28 pm
My particular LEDs were green and white.
4  Using Arduino / LEDs and Multiplexing / Increasing Brightness Linearly on: July 27, 2013, 01:16:02 pm
I understand that LED brightness seems to be logarithmic as a function of duty cycle. In other words, perceived brightness = log(duty cycle) or that as the duty cycle becomes higher, the perceived differences in brightness become more imperceptible.

A person on the AVR Freaks forum posted this thread on how to use the formula "brightness = log(10^(duty cycle)) = x" to cancel out the log using a lookup table or linear interpolation.

Is there a name for this kind of "linearizing using the inverse"? I searched wikipedia and found "Inverse problem" but it got complicated really quickly with matrices and I couldn't follow.
5  Topics / Product Design / Re: How does one begin SMD soldering? on: December 01, 2012, 06:34:41 pm
Alright then. I have access to a hot air station. Where would I obtain solder paste and an appropriate syringe?
6  Topics / Product Design / How does one begin SMD soldering? on: December 01, 2012, 04:22:50 am
I have looked at many design recently--like all the Arduino clones on Kickstarter and pretty much any prototype circuit--they either use breadboards and Arduino shields or complete SMD components. I understand that SMD components are used because they are smaller and cheaper DIP components. I also completed a board recently where the cost of the PCB was more than all the components combined. That's a little ridiculous. I want to move to SMD parts. However, I am at a standstill.

It is difficult to hand solder even a relatively large SOIC-24 even with a nice Hakko-FX888 with a curved tip, although my solder was pretty thick. I tried to flux the pads and drag solder, but I seem to create many bridges and removing even just one is miserable. For this reason, I want to move to non-iron based methods such as the reflow skillet with solder paste, however I do not know where to buy it. I heard that it must be kept cold or it will lose its chemical properties, and I hear it is applied with a syringe. Is there a tutorial and accompanying product that I may buy to hopefully solder TQFPs 32s, LQFP 100s, and maybe QFNs?
7  Products / Arduino Due / Re: JTAG Debugging on: October 23, 2012, 09:23:59 am
If I understand correctly, to use the JTAGICE II or up, you have to use it through Atmel Studio and there are no cheap clones available. What application would we use with our own JTAG debugger to debug with the Arduino IDE? And you need all source code in order to debug, correct?
8  Products / Arduino Due / JTAG Debugging on: October 23, 2012, 12:26:54 am
I am very excited to finally see the Due in the wild. I am eagerly looking for its soulmate, the JTAG debugger. What are our options for debugging 96kb of code? Can we use low-cost debuggers like the LPC-LINKs or are Atmel's programmers like the JTAGICE II our only choice?
9  Using Arduino / Motors, Mechanics, and Power / Re: SOLVED: Problem when plugging heavy load devices on the same outlet as Arduino on: October 10, 2012, 04:45:19 pm
Interesting..so in series with the cap. That would limit the rate of charge and discharge to about 22mA max. I wonder why that fixes the problem.
10  Using Arduino / Networking, Protocols, and Devices / Re: How to get the JY-MCU bt board to work on: October 10, 2012, 04:40:58 pm
I would recommend changing the baud rate on the bluetooth device, otherwise other boards of whatever entry you changed will not work without more modification to boards.txt. I am not sure about less distance at 57600--you have to determine this empirically.
11  Using Arduino / Motors, Mechanics, and Power / Re: Problem when plugging heavy load devices on the same outlet as Arduino on: October 10, 2012, 04:38:10 pm
UPDATE:
I added a 220Ohm resistor from -cap->GND.... AND IT WORKS! no more surge problems!

220 between 5V and ground? Or somewhere else?
12  Using Arduino / Motors, Mechanics, and Power / Re: Problem when plugging heavy load devices on the same outlet as Arduino on: October 10, 2012, 04:36:07 pm
You will have to use another, higher voltage power supply with your own regulation to reach the stage before the 5V. I used 9V. (this might solve the issue by itself without the giant cap)

The phenomenon we are experiencing resets the Arduino without letting it run any setup code it seems. You need to enable the WDT in hardware so that it is always on by setting the WDTON fuse setting on the ATmega328. You will need an ISP programmer like the AVR ISP mkII for this (preferred) or you can use another Arduino, but the ISP programmer is much cleaner and quicker. After you find your programmer, you can either use the Atmel Studio 6 "Device Programming" panel or just command-line avrdude (quicker but easier to brick your chip). Then the WDT will always be on for I believe 64ms, which you can change in the first line of your setup and throughout your program.
13  Using Arduino / Motors, Mechanics, and Power / Re: Problem when plugging heavy load devices on the same outlet as Arduino on: October 10, 2012, 04:21:22 pm
I tried connecting a 2200uF capacitor 5V>GND, but this did not solve the problem.

I replicated the problem by plugging in a fridge, a microwave, and a water cooler into a power strip and then connecting the arduino usb to the other plug in the same outlet. When I flip the power strip on/off, the arduino eventually hangs and loses connection.

This is a really annoying problem. :/

I think that is going a little far. You only need to simulate with the appliances that will be used there. (and the microwave does not use any energy when plugged in)

I put my cap across the power supply output, not the 5V. Energy stored in a capacitor varies quadratically with voltage. My circuit ran for three days and never reset. Even if it does, I turned on the WDT for two seconds as a redundant safety measure.
14  Using Arduino / Networking, Protocols, and Devices / Re: How to get the JY-MCU bt board to work on: October 10, 2012, 02:49:40 pm
If you have already verified two-way communication without a USB cable while not on the roof, then it should work on the roof unless a wire comes loose or the asymmetry between Bluetooth transmit power causes one of the two signals to degrade.

I do not know why your computer is locking up while trying to program over bluetooth. If I had to guess, it is getting stuck at the connection establishment, something a USB cable does not have to worry about. I would just end the Arduino process or disable the bluetooth adapter in device manager instead of rebooting. Again, I do not recommend programming over bluetooth. The JY-MCU already provides an easy to use serial connection but was not meant to program.

Also when I said "up arrow (on either RX or TX)", I said "either" because I could not remember which one it was. The pins don't do the same thing.

You seem to know what you are doing so I trust you can troubleshoot.
15  Using Arduino / Networking, Protocols, and Devices / Re: How to get the JY-MCU bt board to work on: October 10, 2012, 01:56:35 am
1) Try using a very simple sketch that just outputs a message every second with just the Arduino first. Program it with a USB cable, then remove it from the computer and attach the JY-MCU so that the up arrow (on either RX or TX) goes to TX (pin 1) on the Arduino. If you connected it correctly then you should be able to see your data.
2) When you pair and open the serial port (you have two-either one should work), the LED should shop blinking and be solid on. This means the serial port is open and you should be seeing data. You cannot send AT commands in this mode. If you want to send AT commands to change baud rate and name, follow steps in post #3. You cannot upload sketches in this mode unless you press the reset button at the right time. Uploading sketches requires a reset wire which the JY-MCU does not provide. I made an ATtiny circuit to watch the LED and reset the microcontroller so that sketches can be uploaded, but uploading code is five times slower and sometimes it fails. It is flawless if it actually finishes an upload though.
Pages: [1] 2 3 ... 9