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1  Using Arduino / General Electronics / Re: picture in picture chip on: April 06, 2014, 09:52:03 am
I will try there, but I am looking to control the pip chip from an adruino...
2  Using Arduino / General Electronics / picture in picture chip on: April 06, 2014, 05:38:12 am
I am looking for a picture in picture chip that will accept composite video inputs and allow variable sized windowing.

Anyone used one?
3  Using Arduino / Networking, Protocols, and Devices / Re: GPRS basics on: February 24, 2014, 07:54:32 pm
Thanks for your comments.

I'll look into wake on lan options on my modem.
4  Using Arduino / Networking, Protocols, and Devices / GPRS basics on: February 21, 2014, 05:55:12 am
I'm looking for some basic info on using cellular modems. I have spent some time googling and I wanted to make sure I have understood what I have found so far.

My understanding is that on 2G GSM networks it is possible to have essentially a point to point data call between two subscribers. This is a CSD call and limited to 9600baud.

Now that we have 3G and 4G, CSD is being dropped by a number of service providers.

On 3G GPRS systems, data comms is basically done over the internet using normal TCP/IP protocols. This means a Client Server approach and makes data calls from subscriber to subscriber (Client to Client) more difficult unless both ends are permanently connected   (which may be impossible with service providers preventing it).

The normal method is that subscriber (client) connects to a Server (PC on the net) and data transfer takes place.

In a situation where the remote node is a battery powered device requiring it to be in sleep mode most of the time, it cannot be contacted by the Server or by another cellular modem. The get around for this is to send a text message to it to make it wake and call the server (or a voice call that is dropped and not answered - the ring wakes the device).

So essentially, as 2G becomes obsolete, mobile data comms becomes IP.

Texting remains a simple method to pass small amounts of data about.

Is this more or less correct?

If you have two cellular modems and you dial one with the other, do they connect and provide a transparent data link, like old fashioned PSTN modems did? Or will they only do this if CSD is supported by the carrier?

In my application the remote device with the modem will be asleep most of the time, waking every so often to gather data. At some point the device must be contacted by a central station and it's data uploaded. To do this the central station must ring or text the remote device to wake it and then the remote device establishes an IP connection to the central station to deliver it's data.


Thanks for your help.

5  Using Arduino / Displays / Re: U8glib: Graphics Lib for LCDs and OLEDs on: January 19, 2014, 01:17:48 pm
So it uses HW SPI if you define the HW SPI pins in the setup function?
6  Using Arduino / Displays / Re: U8glib: Graphics Lib for LCDs and OLEDs on: January 18, 2014, 02:02:11 pm
Just to confirm when using U8glib on Arduino, it's a Software SPI and can therefore use any pins?
7  Using Arduino / Displays / Re: No TFT library in 1.5.2? on: December 30, 2013, 05:42:17 am
I have just installed 1.5.5 and the tft library is there, I thought I had read that it was included from 1.0.5 onwards and it didn't seem to be there my install of 1.5.2.

8  Using Arduino / Displays / No TFT library in 1.5.2? on: December 29, 2013, 12:30:03 pm
My install of the Arduino IDE 1.5.2 does not appear to have the TFT library in it...

Everywhere I have looked in the Arduino pages seems to suggest it should be part of the install?

It that right? Can I download it or should I be using the Adafruit library?
9  Using Arduino / Project Guidance / Re: Nano/Mini vs Mega ram capacity on: December 22, 2013, 02:15:40 pm
I have used teensy before and the 3.1 version is quite a beast! I've been looking for very low cost too and the Teensy3.1 is good value for money but it's still nearly 4 times the price of a pro-mini.

I know I can optimise to fit into 2k ram (only 600 bytes to lose) but I was curious to know if there was any info anywhere with the RAM and FLASH requirements of the common libraries.

So how come there's no Arduino with a Xmega128 on it??? They are pretty cheap devices now and you get 8k ram and stacks of hardware....
10  Using Arduino / Project Guidance / Nano/Mini vs Mega ram capacity on: December 22, 2013, 07:30:52 am
I'd like to use a Nano or Pro-Mini for a project as they are small boards but I want to use an SD card, RTC, LCD and Radio.

The problem I face is lack of ram on the 328 based boards.

So two questions:

Is there a quick ready reckoner to find out the ram usage for each of the Arduino Libraries, or do you just build on a Mega and use a ram usage checker to see if it would fit on a 328?

Is there a small Arduino board with more than 2k ram?  Maybe I should look at a Teensy?
11  Using Arduino / Storage / Re: SD card problem on Mega, can a card go faulty via SPI but still work in PC? on: December 21, 2013, 05:39:43 am
After some more playing, way way too late at night, I have come to the conclusion that is odd problem must just be down to the 5v SPI levels causing reliability problems.

After finally getting the reader working again by connected both grounds, It decided to stop working and then to only work with both grounds disconnected!

I'm going to ditch the cheaper SD card modules and go for the micro SD reader with the proper level shifter. It's 4 times more expensive but at least I know it will keep working from one day to the next!

It's amazing that something that worked fine for months can suddenly decide to stop, but that's what comes of using things out of spec...

In the mean time, if anyone has a source of really economical 5V compatible SD card modules, in the UK, let me know. At the moment I'm looking at the one Hobby Components have for £4.50.
12  Using Arduino / Storage / Re: SD card problem on Mega, can a card go faulty via SPI but still work in PC? on: December 20, 2013, 08:33:46 pm
OK looks like its a ground problem.

I connected both GND pins on the card module to the Gnd pins on a Nano (either side of the usb socket) and the card works!

Or maybe it had actually locked up the card because no I can put the grounds back to before - one ground wire to the GND pin next to the Vin pin and it still works!

i have been swapping cards between a Nano and a Mega 2560 and I also formatted the card again with the pc.

For some reason it's just decided to go again...

Maybe it got corrupted at some point but the PC never had any problems reading it....

Now I can get on with what I wanted to do two days ago!!! 
13  Using Arduino / Storage / Re: SD card problem on Mega, can a card go faulty via SPI but still work in PC? on: December 20, 2013, 07:58:43 pm
Just tried SDfat and the SDinfo example returns :

card.init failed
SD errorCode: 0XA
SD errorData: 0X1F

(that's ACMD41 initialization process timeout)

and with no card in the slot :

card.init failed
SD errorCode: 0X1
SD errorData: 0XFF

So it is detecting something.
14  Using Arduino / Storage / Re: SD card problem on Mega, can a card go faulty via SPI but still work in PC? on: December 20, 2013, 05:49:30 pm
Yes, that the module.
Crazy thing is, I had it working fine a few days ago! I had stripped the board down to do something else and today I wanted to use the SD card again.
I thought I may have blown the card but it reads and writes fine on a PC.
I must be missing something really obvious, but I have checked and triple checked wiring. I have tried 2 cards and 2 interfaces.
I know the spi port worked as I used in with a radio module.
Maybe I will have a eureka moment tomorrow!
15  Using Arduino / Storage / SD card problem on Mega, can a card go faulty via SPI but still work in PC? on: December 20, 2013, 01:26:27 pm
Hi all,

I am driving myself slightly nuts trying to get an SD card going on a Mega 2560.

I've had this card working in the past and I've been using the same code (and tried all the examples) but the card refuses to play ball.

The card works fine when plugged into the PC card reader.

Is it possible for it to go faulty when being read via SPI and still work when being read from a PC?

I have these connections:
SD card    Mega
5v             5v
Gnd         Gnd
MOSI      51
MISO      50
SCLK      52
CS          53

(i've tried CS on other port pins and set 53 to output regardless)

What's bugging me is this has all worked fine before!

On the scope I can see clock and MOSI going and there are just single pulses coming back on MISO.

There's no level shifter on the SD card interface board and I've never used one in the past either. (it's an lc studio card module)

This uses pin 45 for CS

#include <SPI.h>
#include <SD.h>

void setup() {
  // put your setup code here, to run once:

  Serial.println("check for SD card");
      Serial.println("SD card found");
     Serial.println("SD card NOT found");


void loop() {
  // put your main code here, to run repeatedly:

Any ideas or suggestions would be most welcome!
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