Show Posts
Pages: 1 ... 384 385 [386] 387 388 ... 782
5776  Using Arduino / Programming Questions / Re: Can I set pinMode other than analog and digital pins? on: March 04, 2013, 06:18:23 pm
ATmega32 ??   Do you mean ATmega328 or ATmega32U4 ?

Basically pinMode works with pins that are defined via the pins_arduino.h file for the relevant variant.
5777  Using Arduino / General Electronics / Re: Very simple resistors question on: March 04, 2013, 06:12:05 pm
If the LEDs are different colours you are likely to run into problems this way - if the same
colour then it will work better (but current distribution won't be as balanced - this may not matter)

Another approach is to PWM the supply to the existing LEDs - reducing the average brightness
without changing the resistors.
5778  Using Arduino / General Electronics / Re: What kind of oscilloscope should I buy? on: March 04, 2013, 06:03:54 pm
There are some really tiny breadboard mountable scopes which look enormous fun: http://www.gabotronics.com/development-boards/xmega-xprotolab.htm - I haven't tried one personally but the price is reasonable for what it is I think.
5779  Using Arduino / Programming Questions / Re: DS1307 and writing problem into 56 internal ram on: March 04, 2013, 05:49:16 pm
Can you clarify which library and version?  And do you already have code (its much easier to
give concrete examples relating to existing code)

Conceptually the DS1307 looks like a 64 byte non-volatile RAM with special behaviour of the
first 8 addresses.  The I2C interface allows specifying a starting address and then writing or reading
consecutive bytes from that point.
5780  Using Arduino / Sensors / Re: analogRead() reading non-existent fluctuation? on: March 04, 2013, 10:57:11 am
You probably need low-pass filtering on the sensor inputs - something in the range 1nF to 10nF to ground for both
green and white wires ought to help - the leads to the sensor may be picking up noise, the sensor itself may
be noisy.

Multimeters use integrating ADCs so they effectively low-pass filter down to 1Hz or less bandwidth - the ADC on
the Arduino has a bandwidth more like 10kHz.
5781  Using Arduino / Motors, Mechanics, and Power / Re: Long range PTZ turret on: March 04, 2013, 07:16:18 am
The DC motor has no encoder so no accuracy at all.  The actual precision of the stepper motor will be limited by
the backlash in the gear system (which I believe is not 64:1 as they claim, but a ratio very close to that - I seem
to recall a thread about this a year ago).
5782  Using Arduino / Motors, Mechanics, and Power / Re: dc motor as a variable resister? or potentiometer? or encoder on: March 04, 2013, 07:11:55 am
Not a normal motor.
Perhaps a brushless motor, but I'm not sure.


Not really - although for a constantly turning shaft you can measure the number of electrical cycles
and act as an encoder - but stationary motors produce no signal, and very slowly moving one's almost
nothing.

What are you trying to detect/measure?
5783  Using Arduino / Displays / Re: SSD1963 controller with 7" TFT (horizontally mirrored image) on: March 04, 2013, 07:04:18 am
The most promising option seemed to be:

0x36 Set_address_mode

BUT

NOTHING happens no matter what I change the value to, in fact if I comment out the line it makes no difference.

Address mode only changes the behaviour on sending multiple pixels - IIRC the UTFT library sets up bounding
rectangle before drawing lines / blocks and then sends the right number of pixels - the bounding rect ensures
all the pixels end up in the right place whatever scan-direction is used.

The gate-scan and source-scan bits are what you need to find.
5784  Using Arduino / Displays / Re: Uno and 7" LCD on: March 04, 2013, 06:59:26 am
21 level shifters???
5785  Using Arduino / Displays / Re: Uno and 7" LCD on: March 03, 2013, 07:03:12 pm
That display is 3.3V logic and 16 bit parallel only, so you'll need 21 pins to talk to it....

A 5V display with 8bit parallel support would be easier...

One way to reduce the pin count is a couple of 74HC595 shift registers (run at 3V3) to drive the 16 bit databus
using the Arduino SPI hardware, and then you'll only need about 8 level shifters rather than 21.
5786  Using Arduino / Displays / Re: OLED Library Messing Up RFID on: March 03, 2013, 06:56:21 pm
Also check if there's enough spare memory perhaps?
5787  Using Arduino / Displays / Re: SSD1963 controller with 7" TFT (horizontally mirrored image) on: March 03, 2013, 06:52:39 pm
All these LCD drivers have a bit to control gate-scan direction and a bit to control source-scan direction,
check the datasheet for where these are in the registers.  Don't change the RAM addressing unless you
want to switch landscape <-> portrait - if I remember correctly.

Again if I remember rightly the usual set up is that the RAM addressing bit simply transposes X and Y, which
means a reflection about a diagonal.  There are 8 combinations of these 3 bits giving access to every
rotation and refection sense.  Rotating by 90 degrees involves changing the RAM addressing and one
of the other reflection bits.
5788  Using Arduino / General Electronics / Re: M7 Diode on: March 03, 2013, 06:46:23 pm
The series protection diode should ideally be a schottky diode, then the voltage drop would be more like 0.3 to 0.4V

In fact there are few circuits where a silicon diode is preferred over a schottky diode - schottkys' main weakness
is higher reverse leakage at high temperature, but is generally superior for most uses below 60V or so.
5789  Using Arduino / Motors, Mechanics, and Power / Re: Stepper motor shield supporting 4 or more stepper motors on: March 03, 2013, 06:36:31 pm
Hi,

I'm currently trying to build a DIY pick-and-place machine as was wondering if there is a motor shield compatible with the Arduino Mega2560 that supports 4 or more stepper motors. I've searched the web for days and have not found anything that does. The closest I've come is the Makerbot Motherboard, but it doesn't seem to be compatible with the 2560. I am new to this so any help would be greatly appreciated.

Regards,
Lee

How big are your motors - over 1A or so is going to be more problematic.  NEMA 17 size is likely to be
fine with this (make sure you get low-resistance low-inductance bipolar motors for these A4983 and A4988
driver boards)
5790  Using Arduino / Motors, Mechanics, and Power / Re: arduino with DE10 Programmable Brushless ESC on: March 02, 2013, 09:16:19 pm
Yes, Servo.  You need to find out what arming sequence the ESC needs too (trial and error - but often min-throttle for several seconds
will work).


[edit:  oh yes, watch out for that 6V BEC - don't try connecting it to 5V logic!]
Pages: 1 ... 384 385 [386] 387 388 ... 782