David - I've got an Xprotolab from Gabotronics. If you can get past the tiny screen, it works pretty well. I've used it for debugging I2C, SPI, RS232 and PWM.
Based on what you wrote, I'd say the Arduino is about the same in complexity as the PICAXE. An mbed is a little more difficult, but not by a huge margin. A raw PIC isn't, in concept, that much more difficult. In practice, it seems to be a lot more complex though. There are a lot of little things that keep an implementation from being smooth.
@Max,Duane thanks...I've always found the idea of taking to multiple devices over the same 2 I2C wires fascinating....and the Picaxe makes it so easy. Where I am very conscious of falling a bit short is that I have nothing to compare the Picaxe with - is it as easy on the Arduino for example? I guess any MCU with an I2C port will have some dedicated instructions for it so you don't have to code all those timings from scratch.....and there are code libraries and examples you can use as well.
I'd love to get one of those Tektronix scopes that do the I2C decoding for you. (I tried to win one recently but no luck :-) But Gabotronics make some tasty goodies that decode I2C at a very reasonable price. I have an older one - must check if it does this.
@Karen now there's a thought - I could charge for photos of your name in lights! (Better get my photo quality up a bit first though - these displays are SO difficult to photograph! If you have the flash bright enough to show the electronics decently, the display appears so faint you can hardly read it. And if you get the display right everything else is dark. If you don't use flash the display characters burn out but everything else is dark.....
In the end I put more and more tissue paper over my flash to diffuse & lessen that light and it worked a bit better.
There are so many people on EET that I regard as friends and look forward to meeting at EE Live - hold thumbs that I get there!
@Max when I first unpacked this display I thought: "Now THAT is a display!" so it kinda flowed from there. I just wrote to the company to ask if they still have bezels for it. They don't have a datasheet on their site; I got it from somewhere else. That always infuriates me - a company should be proud enough of their products to keep info on the old ones available, even for guys like me. I got 3 of these displays and am thinking now about what I could use them for.
I'm a big fan of I2C myself. It infuriates and mystifies me at times though. I've taken to using an Arduino as my test bed for I2C. When I'm writing I2C for one of my PIC MCUs, I'll use the Arduino as the master so I know that I'm sending good data. Doing so also makes monitoring the data easy via the console. It sounds like the PICAXE would have similar utility.
I also meant to say that it's very encouraging seeing someone playing with I2C. I haven't used it myself yet, but I'm going to be using it extensively with my Arduino-powered Robot to interface to the motor controller and the sensors and stuff, so hearing about your success makes me feel more confident.
Hi David: This may be the one and only time I see my name in lights, but thank you for the well wishes and a happy new year and an awesome 2014 to you and your family. How wonderful is it that we've become such great friends, living halfway around the world from each other?? Karen