Rick's b.log - entry 2016/10/30

Don't buy a Brother inkjet

Either way. I can't say I'd recommend Brother, given this experience...

USB graphics tablet on RISC OS

I bought myself a graphics tablet, a Tavla 5. Nothing special, but it does the job. I plugged it in to RISC OS but it didn't do anything more than act like a mouse. I was able to work out the data format (though I now know that a correctly formatted HID descriptor describes the data format too; though you'd be shocked how many tablets give duff HID descriptors).

And that's where things rested for an entire year. Let's face it, I do most of my graphics work on the PC using PhotoImpact5 and I'm crap at drawing, so I don't use the tablet much.

With a bit of support / egging on by Chris, and some invaluable information from Ian Jeffray (who wrote the original serial port tablet driver way back when) I was able to pick apart what the older driver was doing and what PhotoDesk was expecting in return. And somewhere along the way it seems that I was supposed to write a driver for RISC OS. Oh, well, okay. I don't really write code for the PC any more... ☺

So here are two photos. The first is my tablet. I have photocopied the manga girl at 182% size (it was one of the presets on my printer; 15x10 to A4 or something? black and white printing still works...today at least!) and inserted it in the flap of my tablet so I can 'trace' it.

• The manga is a sampler of Hyakumanjō Labyrinth, which is called Dédale (Daedalus?) in French.

Since I originally wrote this text for my blog, I have done a fair bit of work on the driver. There are a number of things yet to be done, however the driver can recognise tablets based around the WP5540. There is some support for other tablets, but it isn't complete so I'm not going to say anything more about that yet. The WP5540 seems about at close as one gets to a "standard" protocol. That said, some of the more advanced tablets perform additional functions such as 'tilt' and various on-tablet buttons, so those will necessitate additional data. One of the problems is that this sort of thing is rarely documented. Wacom, for instance, tell you to talk to their fancy tablets by using a special driver. And if you really really need to know the low level stuff, then you are supposed to get in touch to sort out an NDA. If, I guess, they feel your reasoning is justified. Like, oh, I don't know, the inability to run a Windows driver on RISC OS?

Here's a simple rubbish video I threw together. It shows what needs to be shown.

Unfortunately there seems to be a rather unpleasant problem with PhotoDesk where sending an Adjust (right button) click from the tablet will freeze the entire machine. I don't know why. I think I can lay blame at PhotoDesk because firstly the button presses work elsewhere (RISC OS itself, OvationPro, etc) and secondly if my driver specifies that the Select (left) button is being pressed, then... well... look at the above picture. However if I alter the driver to send an Adjust click instead, instant freeze. Weird.
However, since it's a rather nasty reaction (only recovery is to reset the machine), I've modified the current version of the driver to simply not send Adjust clicks.

Your comments:

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YogiCK, 1st November 2016, 15:23

I'm using my Brother DCP-J145W since 2013, always with cheap cartridges (10PLN/cart, ~2,5€/cart), no problems with ink as of today. Maybe just print few lines of color text once a week to prevent drying of ink.

Rob, 16th December 2016, 19:16

Have to agree re fixed printheads and ink-only cartridges. Epson printers have the same issues. Make for cheap ink, but unless you use them constantly, they dry up and you might as well bin them there and then.    These days I mostly use lasers - bit more expensive to buy (if you get them new) and toners can be pricey, but they last for ever! I have an inkjet I use occasionally elsewhere (off a pair of 12V batteries because I have no mains there!) and that's an HP because the carts have the printhead built in - if I have a problem I just swap out the cart and worry about it later.

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