John's Ramblings

Arduino Ethernet

I have been playing with ethernet for the Arduino – I got hold of a Nuelectronics EtherShield and started to make it work. The examples were badly formatted and difficult to read but I learnt a lot of TCPIP and got it working fine. The issue here is that as you are down at the TCPIP layer there is a lot of code to manage and you are limited to quite small packets (as the Arduino does not have a lot of RAM). However this is a great larning tool for Ethernet protocols.
So my next step was to look around for something that could do more – I came across the LadyAda Ethernet Shield kit and decided to get this and a XPORT ethernet module. I’ve put these all together and I can now communicate with larger packets – I tried the provided “Read from Twitter” example, after altering it to match the current Twitter formats it worked fine. I wasn’t receiving the whole page but around 11 Kbytes is not bad (compared to around 500 bytes for the EtherShield). It uses a library called NewSoftSerial, a great improvement over the the one provided in the Arduino kit; it uses interrupts to get the data. I couldn’t get consistant performance over 19200 baud so I am looking forward to a release that properly implements RTS/CTS then we should be able to run comfortably at 57600 baud.

ByVac I2C LCD controller

I got the ByVac BV4208 working, the library is here.
To use include the library “Wire” and then “ByVacLCD” (I don’t know why you have to include “Wire” even though the library already includes it but you do – I spent ages on this one). Note as this is I2C it uses analog inputs 4 and 5.

#include <Wire .h>
#include <ByVacLCD .h>
// declare the object – address in the data sheet is 0x42 but you
// need to divide this by two to get the ‘normal’ 7 bit I2C address
// – the low order bit is added on by Wire.
// this declaration is for 4 rows of 20 characters.
ByVacLCD bv = ByVacLCD(0x21,4,20);

void setup()
{
bv.init();
bv.print(“Hello World”);
}

void loop()
{
bv.setCursor(1,0);
bv.print(millis());
}

Arduino LCD test

I got hold of a I2C Real Time Clock module and a two line LCD display. Managed to get them both connected and working.

I am now working on adapting the display to I2C using a ByVac BV4208.
I have written the code and tested on a breadboard using a Roboduino nano (same as an Arduino Nano) – now to build the veroboard version.
I destroyed the Schottky diode on my nano when a loose wire shorted out 5v to ground and the USB supply overloaded. It all still works but will not power from the USB anymore.

Arduino interface to TMB880CF

I found an old LCD thermometer – got it from Maplin many years ago. I hunted for specs on the web but all I could find was that it used a serial data stream. It runs from 1.5V so I used an NPN transistor and a schmitt trigger NAND gate (old 74LS132 chip I had) to interface through to 5V (note to self – I need to find a program to draw my circuit diagrams so I can publish them). I used interrupts on the falling clock pulse to get the data. The Arduino code is here.

From Richard Norman on forums.parallax.com
The thermometer device measures the temperature every 10 Seconds and outputs
the data as serial data as 13 pulses on two pins as follows:
Thermometer Pin 9 (Data out):
Thermometer Pin 10 (Clock Pulses Out):
With the exception of the first clock pulse (which has a duration of 1mSec),
the clock pulses occur 0.125 mSec after the start of the data pulse and last
for 0.125 mSec.
The data bits have the following significance:
D01 – Degrees Celcius Polarity
D02 – 80
D03 – 40
D04 – 20
D05 – 10
D06 – 8
D07 – 4
D08 – 2
D09 – 1
D10 – 0.8
D11 – 0.4
D12 – 0.2
D13 – 0.1

Arduinio

I heard about the Arduino on the BBC website recently (story) and have been playing with it. It appears to be exactly what I was looking for about ten years ago!. I’ll post here as I achieve anything.

Chelsea Flower Show 2009

Our trip to the Chelsea Flower Show is on Wilbeary’s blog.

Fox in the garden

Imagine my surprise when I looked out of the back window earlier today

Budapest again

We had a lovely time in Budapest

Views from Castle hill

Police Smart car on Castle Hill.

Moskva square

The Cave Church on Gellert hill

Moskva square – manual change of tram points

New York hotel and cafe

Gerbeaud cukrÃ¡szda

Budapest scenes

Has the cow exhibition reached Budapest?

Storm clouds over the Grand Market

Robert visits us

After the trauma of last weekend when Robert was driving in Sheffield, lost his brakes, went round a roundabout and into a layby, he was just deciding which tree to hit in order to stop when his rear wheel fell off and the car ground to a stop. His original car (Megane) has been written off.
Since then he has got a KA and been told he ought to wear glasses to drive! Tonight he came home for a brief visit.

More snow

We woke up this morning to 3 inches of snow – travel disruption again.
It all looks very pretty – I’m glad I’m working at home. I don’t see Maria getting to Patchings today.