Ethernet based IO module

I've got a development kit from SitePlayer and was wondering if anybody would be interested in an IO expansion module for the Mk2/2a Empegs that uses ethernet to connect?

It's got 8 IO pins and a serial port as well. I haven't played about with it much but it seems pretty simple if you only need basic IO.

The individual chips are quite expensive at $30 excluding P&P though and you'll need a RJ45 socket with inductors as well.

- Trevor

Check out this thread for an idea of how to use that thing. I don't own an Mk1, but others may appreciate running DisplayServer on it.

I swear I'm going blind. Yesterday it was the post about turning on and off the LED and now it's this one

I'll have a look into how much this chip can actually do. If so then I could make a simple displayserver type thing for Mk1 people. I don't personally need it since I've got a Mk2a.

Anybody want this?

- Trevor

It would be limited to the speed of the serial port, right? What is that, ~300k?

300k? More like 14k/s or 28k/s via the serial port! It's USB that's 300k/s I think...

It is possible to do this just about but the screen refresh isn't going to be that impressive.

- Trevor

There are only 128*32*2 bits in the empeg's display: 16,384 bits or 2,048 bytes. At 115,200 baud you can send the whole thing 5 times a second without any compression or delta-encoding.

Sending the actual screen data won't be the hard part. It's just that this SitePlayer chip only accepts data from the serial port in 16 byte chunks with a 2 byte header. It's just more of a problem syncronising it.

Isn't the empeg screen updated a lot more than 10 times a second though?

BTW I get 128*32*2/8 = 1024...

- Trevor

Yeah, my bad. I meant 230,400. Didn't one of the Empeg team get that from the serial port? Even if so, does the module support that fast of a serial connection?

Nope. Afraid not. Only does 115200 which means 14k/s max

- Trevor

Nope. Afraid not. Only does 115200 which means 14k/s max

No, dearing is right, the car player's serial port will do 230,400bps. The problem isn't in the car player, it's in the PC. See here.

Sorry, I should have been clearer. The SitePlayer module only does 115200

- Trevor

I think he was refering to the serial port on the module he is using being limited to 115200, not the empeg serial port.

I was thinking in general terms, not for this specific module. I'm building a remote display that connects to the serial port. The empeg probably does update faster than 10 times a second but only the animation. I can't think of anything in the normal UI that changes faster than the track time once per second. And 10 CPS was a worst-case, brute-force estimate. Only sending the changed portion of the display would be faster. Just try the VNC software over a modem.

Yeah, 1,024. I was adding bits: 7+5+2-3 = 11 instead of 7+5+1-3 = 10.

You're right. You don't really need that high of a refresh rate if you're just interested in remote control of the empeg and some sort of visual feedback.

I was thinking of just sending the entire display each time purely because it's just easier to write the client. I'll have a try later on when I've got more time.

Tell me how you get on, could be quite interesting

- Trevor

FYI, song and album title scrolls are pretty fast.

Good point. I'm 600 miles from my empeg but I seem to remember that a title scrolls across the display in 3-4 seconds. That would mean they roughly redraw a title 32 to 42 times a second to move it across the 128 pixels.

I suppose Mk1 folks could even use something like this as an ethernet interface (slow, but useable) for kftpd/khttpd in Hijack.. (currently not part of the Hijack mk1 builds, but that's easy to change..).

So, I've read *everything* on their web site, and it is still totally unclear what this SP1 has for interfaces. It obviously has 10baseT, and 2-wire serial. But what else does it have?

-ml

Yeah. Their site doesn't really say much.
It's got 10baseT, 3 wire RS232, SPI, some general I/O pins and I think it's got an ADC but I'm not sure...

It's actually just a flash upgradable Phillips 8051 clone glued onto a small PCB with a RealTek ethernet controller on the back

- Trevor

Thanks for ethernet hardware link,

Looks like a really usefull piece of kit, I'm sure it will come in usefull for many other projects!

Watch out for internet doorbells, internet microwave, and anything else I can get my hands on!

Mark.