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by domesday
Fri Apr 25, 2014 8:07 am
Forum: Compute Module
Topic: Power Questions
Replies: 3
Views: 1922

Re: Power Questions

As the BCM2835 was designed for mobile is there a low power mode, I don't seem to be able to find it the processor seems to run at full speed all the time. There has to be a way to reduce the power use when idle otherwise if it was in a mobile device the battery would run out in a couple of hours.
by domesday
Mon Apr 21, 2014 5:23 pm
Forum: Compute Module
Topic: Power Questions
Replies: 3
Views: 1922

Power Questions

I'm hoping someone close to the BCM2835 and Compute Module might be able to answer some questions about power. The first question is about the Core SMPS onboard regulator. On the Pi this is connected to the 5V line presumably this is to save drawing extra power from the 3V3 regulator. Is there any t...
by domesday
Sat Jun 29, 2013 9:06 pm
Forum: HATs and other add-ons
Topic: Powering Pi with the Gertboard/ Multiface????
Replies: 2
Views: 1355

Re: Powering Pi with the Gertboard/ Multiface????

The raspberry Pi can be powered by supplying 5V through the GPIO header so yes in principle you could power the Pi from the interface board. You would however need to use either a 5V regulated supply or install a regulator if you are are running from batteries that have a higher voltage.
by domesday
Fri Apr 26, 2013 2:56 pm
Forum: HATs and other add-ons
Topic: Connect LED strip to Gertboard
Replies: 2
Views: 2015

Re: Connect LED strip to Gertboard

If you just want to tun an LED strip on and off then you would connect your 12V supply to the open collector and then connect the LED strip to switch it on and off.
by domesday
Sun Apr 14, 2013 10:52 pm
Forum: HATs and other add-ons
Topic: Motor won't reverse
Replies: 8
Views: 3031

Re: Motor won't reverse

some motors are not reversible, if you reverse the polarity of the leads to the motor does the opposite happen ?
by domesday
Mon Mar 25, 2013 12:09 pm
Forum: Other projects
Topic: MagPi Website has died? (solved)
Replies: 6
Views: 2906

Re: MagPi Website has died?

Nothing to worry about, the domain has been transferred to 1and1 hosting but probably not been configured yet.
by domesday
Tue Mar 19, 2013 5:14 pm
Forum: Automation, sensing and robotics
Topic: Reading a speed sensor with gertboard
Replies: 2
Views: 1098

Re: Reading a speed sensor with gertboard

The output will likely be digital from the sensor, each time the tooth passes it will change from high to low, so you could simply count the number of pulses per second and compare to the number of teeth. For example you have 20 teeth on the wheel so to make a full revolution would require 20 pulses...
by domesday
Tue Mar 19, 2013 10:20 am
Forum: HATs and other add-ons
Topic: Basic photocell reading using the Gertboard (works)
Replies: 10
Views: 8832

Re: Basic photocell reading using the Gertboard (works)

Now perhaps you could try using the analogue input on the gertboard for better results.
by domesday
Thu Mar 14, 2013 11:09 am
Forum: HATs and other add-ons
Topic: Grounding 5v
Replies: 7
Views: 1509

Re: Grounding 5v

No it doesn't matter which ground connection you use.
by domesday
Thu Mar 14, 2013 10:42 am
Forum: HATs and other add-ons
Topic: Grounding 5v
Replies: 7
Views: 1509

Re: Grounding 5v

Ground is common to all voltages so you connect a ground connection for 5V or 3.3V devices to the same point.

You will however need to make sure that the output from your device is not 5V as that would cause dame to the Pi.
by domesday
Sat Mar 09, 2013 1:55 pm
Forum: HATs and other add-ons
Topic: Using the Gertboard to program other ATMega chips?
Replies: 12
Views: 3453

Re: Using the Gertboard to program other ATMega chips?

Assuming you are creating the circuit as shown on the breadboard you don't need the gertboard at all, you just need some male to female jumper wires to connect the GPIO headers from the Pi to the breadboard.
by domesday
Sat Mar 09, 2013 10:55 am
Forum: HATs and other add-ons
Topic: Using the Gertboard to program other ATMega chips?
Replies: 12
Views: 3453

Re: Using the Gertboard to program other ATMega chips?

IMPORTANT You can not program a 5V microcontroller from the GPIO of the Pi without a level shifter. If you power the microcontroller from 5V it will result in 5V high signals being sent to the Pi and will cause damage. If all you want to do is program the controller then you can simply connect it t...
by domesday
Wed Mar 06, 2013 5:48 pm
Forum: HATs and other add-ons
Topic: Purchasing Straps
Replies: 11
Views: 2635

Re: Purchasing Straps

If you are searching for straps then that would explain to why you can't find them.

What you need are called jumper wires, some examples..

http://www.tandyonline.co.uk/100mm-fema ... -10pk.html

https://www.sparkfun.com/products/8430?
by domesday
Sat Mar 02, 2013 1:26 pm
Forum: HATs and other add-ons
Topic: Gertboard Connection to Pi (cable twist)
Replies: 17
Views: 6922

Re: Gertboard Connection to Pi

The correct cable without a twist will look like this http://www.tandyonline.co.uk/26-way-rib ... ender.html

Where the connectors are on opposite sides of the cable.
by domesday
Sat Mar 02, 2013 12:11 am
Forum: HATs and other add-ons
Topic: Diagnosis help please
Replies: 6
Views: 1303

Re: Diagnosis help please

Note if you have the original kit version of the Gertboard your power supply and motor must be 12V for it to work, sometimes 9V will work but if your trying to use a motor with a voltage of below 9V it will not work.
by domesday
Tue Feb 26, 2013 4:27 pm
Forum: HATs and other add-ons
Topic: Using ATMega Standalone
Replies: 5
Views: 2415

Re: Using ATMega Standalone

The gertboard runs the ATMega at 12Mhz because it is running from a 3.3V supply.

If you want to re-produce the the ATMega set-up on the Gertboard the easiest thing is to just add a 12MHz ceramic resonator.
by domesday
Wed Feb 20, 2013 6:26 pm
Forum: HATs and other add-ons
Topic: Gertboard components
Replies: 5
Views: 1156

Re: Gertboard components

Not so easy on the LED resistors as they are a common network, i.e 4 resistors with one common connection.
by domesday
Wed Feb 20, 2013 11:23 am
Forum: HATs and other add-ons
Topic: Gertboard components
Replies: 5
Views: 1156

Re: Gertboard components

The value of the resistor array is not critical, it is only a current limiter for the LEDs so even a 5% tolerance would be absolutely fine.
by domesday
Sun Feb 10, 2013 8:24 pm
Forum: HATs and other add-ons
Topic: optoisolators??? Sensors
Replies: 7
Views: 1779

Re: optoisolators??? Sensors

No the Gertboard does not have an opto isolator.
by domesday
Thu Feb 07, 2013 12:27 pm
Forum: For sale
Topic: Nokia Pi LCD + Switch Shield board
Replies: 40
Views: 14094

Re: Nokia Pi LCD + Switch Shield board

You could always cut a notch out where the composite connector is so the board will sit flatter.
by domesday
Thu Jan 31, 2013 10:05 pm
Forum: HATs and other add-ons
Topic: Photos of the original Gertboard & the new Assembled one
Replies: 6
Views: 1996

Re: Photos of the original Gertboard & the new Assembled one

Just the voltage range on the motor controller, otherwise everything is the same.
by domesday
Wed Jan 30, 2013 9:29 pm
Forum: HATs and other add-ons
Topic: Testing I/O
Replies: 4
Views: 1110

Re: Testing I/O

with the button removed from the PCB if it still reports low '0' then you have probably got a short to ground somewhere.
by domesday
Wed Jan 30, 2013 6:37 pm
Forum: HATs and other add-ons
Topic: connecting a sensor to gertboard v2
Replies: 6
Views: 2244

Re: connecting a sensor to gertboard v2

I think perhaps starting with the ATMEGA micro-controller might be the wrong approach if you are a beginner.

Perhaps the easiest thing to do would be use the A/D convertor to read the value of a thermister or analogue temperature sensor.
by domesday
Mon Jan 28, 2013 8:43 pm
Forum: HATs and other add-ons
Topic: Using Buffered I/O to change an LED
Replies: 4
Views: 1565

Re: Using Buffered I/O to change an LED

Perhaps you should try the interfacing articles in the MagPi magazine, will probably help you.

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