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1  Topics / Robotics / Re: Power options and servos on: September 20, 2014, 09:46:20 pm
I want to use higher voltage batteries and wondered if you could recommend where to get  a UBEC other than ebay? I don't have an acc with them anymore...
2  Development / Other Software Development / Re: Set Speed Control of Brushless DC Motor using Servo Library on: September 20, 2014, 07:12:08 pm
Through trial and error, any lower than 60 the motor will stop running, however, it is still relatively fast.  Is this a limitation from my ESC or from my motor?  I would like to understand the process of what is going on better so I can have more precise control over the speed.  Any input would be greatly appreciated!

That is my experience with brushless DC motor/ESC used in R/C airplanes also. They don't control real well at slowest RPMs because the ESC is using electrical feedback pulses sensed on the three motor windings to determine speed and such pulses can be very small at slow speeds. Once above that 'threshold' the speed should be pretty linear Vs the servo.write command values you give it. So I would suggest not trying to attach any kind of external RPM feedback circuitry as the ESC is already a 'speed controller' you just have to characterize it's performance vs your servo write values.

 Also using servo write microseconds rather then servo write degrees will improve the response curve of the motor/esc.

Lastly, know that brushless motor/ESC speed control relationship is dependent on the mechanical load on the motor. Some motor/ESCs work poorly or erratically with no load on the motor. Try to test out using real world motor loads.


i have a stupid Question want to know.
can i use the signal from 3 wires of the ESC to feedback to the CPU to have a close-loop
 i want to know the speed of motor and display in lcd

best regards

 In theory one could but it would be somewhat software challenging analyzing/designing. Also if the motor runs at higher then 5vdc winding voltage then reading them back as analog signals would require external resistor divider networks. 
3  Using Arduino / Microcontrollers / Re: ATmega168 Programming: Which board to use? on: September 09, 2014, 12:58:12 pm
You'd need a bootloader change to receive the sketch to be loaded via I2C vs Serial.

Even then the arduino IDE cannot 'talk I2C' to a target arduino board?

4  Using Arduino / Microcontrollers / Re: ATmega168 Programming: Which board to use? on: September 09, 2014, 12:51:44 pm
Slightly off-topic. But is it possible to program a ATmega168 using the I2C pins? Not the bootloader, but just the programs?

Nope. Your choices are either using the serial USB link using a bootloader or the ICSP pins and a hardware programmer (if even another arduino running the arduinoISP sketch.

5  Using Arduino / Programming Questions / Re: Problems with Serial.begin on: September 07, 2014, 12:01:45 pm
What version of the Arduino IDE are you using?
6  Using Arduino / Storage / Re: How uploaded code are save in the arduino? on: September 07, 2014, 11:35:37 am
Yes - after a slight pause if you used a bootloader to install the sketch.  
It will start with no delay if you used File:Upload Using Programmer and loaded the sketch via the ICSP header using an In System Programmer (ISP) such as Atmel AVR ISP MKii, or an Arduino that was programmed to act as an ISP.

Thank you. Is the reset button on the Arduino to erase all the memory?

No, reset does not erase any code (flash memory), it just causes a restart of the code.

7  Using Arduino / Motors, Mechanics, and Power / Re: Supply Current for Relays on: September 06, 2014, 10:59:34 am
I'm flipping up to 16, 5V relays. Each relay needs 15-20 mA. The MEGA can source 40 mA per pin, and 800 mA overall, though only so much current to a group of pins ( There are other components to this project that will take up power too, and I want to be as gentle on the arduino as possible.
Has anyone heard of such a product or circuit? Thanks.

 Keep in mind that there are two 'current loads' that the relay board presents. First is the digital inputs of the relay board, most use a opto/led input that require about 20 ma per relay channel to turn on. The second load is the relay's coil consumption, and depends of the specific relays used in the module. As far as being able to power all 16 relay channels at the same time while being powered by the arduino's 5V pin that would probably be more then the arduino can supply. Powering the relay board with an external regulated +5vdc of sufficient current rating is probably called for.

8  Using Arduino / Project Guidance / Re: My programs runs on Arduino Uno but not on Arduino Nano on: September 06, 2014, 10:13:34 am
I have been working a board layout for a data logger and from what I have found, the NANO does not have a 3.3v regulator on board.    visual inspection of my NANO confirms that as well.

only when power is fed into the USB port and then into the USB chip, does the USB chip output 3.3v power.

I wound up using a separate 3.3v regulator and went with a 3.3v mini for my project.

 That is incorrect. The Nano (version 3.0 anyway) does have a regulated 3.3vdc output available. However it's an internal 3.3vdc regulator built into the FTDI USB chip and has a maximum output current capacity of like 40 mA. The FTDI chip has power applied to  it even if not plugged into a PC. Both the FTDI and 328P chip are powered from the same board's Vcc source.
9  Development / Other Software Development / Re: Software to programming with logic blocks on: September 03, 2014, 01:26:20 pm
Looks like a reinvention of PLC ladder logic programming?

10  Using Arduino / Project Guidance / Re: Is it possible to use CP2102 instead of ATMEGA16U2 on custom project on: August 26, 2014, 11:28:29 am
Thank you very much for the answer.

But do I have to install any thing like a firmware on the CP2102 or just plug it to the USB port on my PC?

You only have to install the correct USB driver that supports the CP2102, no other software or firmware required. This driver is not supplied with the Arduino IDE so you will have to locate it on the web. Some sellers on E-bay of CP2102 modules show a link to it's USB driver files.

11  Using Arduino / General Electronics / Re: Whats are the holes on this relay for? on: August 21, 2014, 11:45:27 am
You are wiring it improperly if you are using the two end terminals. And as your light is most likely household AC voltage you are in some danger trying to learn as you go. Learn to use the relay with low voltage DC until you understand the NO/C/NC contacts and how they are used in your external circuit.

12  Using Arduino / General Electronics / Re: How to connect V 4-Channel Relay Module to Arduino on: August 19, 2014, 07:22:02 am
I purchase V 4-Channel Relay Module Low Level Trigger with Opto coupler for Arduino
What kind of External power supply need to this relay.  It work with 5 volt but how much current need ?.
And how do I connect it together with  Arduino board ?

If it's typical of many Asian e-bay type relay modules the hook-up would be as follows:

1. ground to ground
2. 4 relay channel input pins wired to 4 arduino digital output pins
3. Board Vcc power to arduino 5V pin, 4 relay coils won't 'overload the Arduino board's 5 vdc.
4. The board my have a movable jumper for power, be sure it is proper position to be powered from Arduino.
5. As you stated in your coding a digitalWrite(pin#,LOW) will turn on the relay channel.

Good luck

13  Using Arduino / Sensors / Re: Rotary encoder troubleshooting on: August 14, 2014, 01:44:42 pm
no one?

Sure. Bet you are using an inexpensive mechanical encoder switch rather then a more expensive optical or magnetic encoder? If so the dreaded "switch contact bounce" is causing your problem of random intermittent multiple steps.  
14  Using Arduino / General Electronics / Re: 4x AA Ni-Mh voltage drop on load on: August 14, 2014, 01:39:37 pm
You guys keep talking of battery packs problem is i cant seem to find anything for a good price!
On ebay  most of them are fake, local stores only have this batteries for digital cameras where can i get nice batteries from??

 Those designed for digital cameras should work fine for servo application as both are higher current/shorter duration type loads. Any battery will have some limit of number of servos that can be manipulated simultaneously due to the specific battery's internal resistance rating.

15  Using Arduino / General Electronics / Re: Current rating on datasheet.. per channel or total? on: August 14, 2014, 01:34:46 pm
It's not a wattage spec, but a current spec.

The wattage-related limits can be calculated with the given specs and the operating values.

 I again disagree, maximum device power dissipation is not a current specification measured in amps. The datasheet is incomplete. Calculate all you want but you don't know what the total device power dissipation value is so can't tell if it's the limiting factor or not at any given voltage/current/# of outputs driven combination.

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