YAPPish (home-made or very cheap) Seatalk display?

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prv

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At the chart table on the new boat, I'd like to display a few pieces of data off the Seatalk bus:

Depth
True heading
Log speed and distance
True wind speed and direction

I don't want to pay hundreds of quid for a Raymarine instrument when I know the components can be had for less than a tenner. I also don't have the panel space for a 4"-square box, I just want a little 4-line LCD display, and I can integrate it into the rest of the panel so it doesn't need a fancy case.

Anyone know of such a thing available for sale?

As far as I know, Angus hasn't produced this exact item as a YAPP, but perhaps I could cobble together parts of his other ones. I do have the necessary tackle for programming a PIC somewhere, though I've never really used it in anger as initial enthusiasm was overcome by lack of patience :)

Pete
 
Like this?
attachment.php


http://www.ybw.com/forums/showthread.php?276102-YAPP-Seatalk-repeater&highlight=yapp
 
AngusMcDoon said:
Like this?
Click to expand...

Heh - that does look very nearly what I want, yes.

I don't want or need that kind of fancy screen, though. I have a 4-line LCD in the bits box (was going to drive it from a small industrial PC that used to upload my electricity meter readings to the Internet as part of a work project) and if I could drive that then I'd be making the whole thing for free :). I guess I'll find code examples online for that and graft it onto your Seatalk decoder and wind calculator. Will PM you an email address for source and interface schematics - thanks!

Pete
 
I did a driver for a 16x4 text display just last week. It runs on a PIC18F26K22 with a clock speed of 16MHz. The display driver chip is the HD44780, which is common for this type of display. The Seatalk repeater runs on the same processor but at 64MHz. The display code may need its timings changed slightly to munge the two projects together. I can send the two projects and you can have a go, or I can do it, but not yet, because it needs to go into my FIFO of things to do.
 
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Thanks for the code, by email. I'll have a look tonight.

I have a couple of PICs in the shed, spares from a kids' educational project a while back (I did the physical assembly, soldering and woodwork rather than PIC programming). Can't remember the exact type, 18F<something> with the maximum available number of pins (we were driving lots of LEDs). How sensitive is the design to the precise model of chip?

I think the display I have can be controlled by serial or I2C, so I was expecting to use a serial port for that rather than timing-dependent code. Is this bit-banging serial, or do our displays have different interfaces?

Cheers,

Pete
 
prv said:
Can't remember the exact type, 18F<something> with the maximum available number of pins (we were driving lots of LEDs). How sensitive is the design to the precise model of chip?

I think the display I have can be controlled by serial or I2C, so I was expecting to use a serial port for that rather than timing-dependent code. Is this bit-banging serial, or do our displays have different interfaces?
Click to expand...

Depends on how much flash, data memory and processor speed yours have. I'm only using timers and GPIOs so no particular processor features are required. The config bits will need to be changed. Buying an 18F26K22 from RS or Farnell is only a beer token or two anyway.

The displays have a different interface. This is the display I use...

http://www.ebay.co.uk/itm/271137734300?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

It has a parallel data interface and a few control lines.
 
AngusMcDoon said:
Buying an 18F26K22 from RS or Farnell is only a beer token or two anyway.
Click to expand...

True. Have to wait for them to arrive, though :)

AngusMcDoon said:
The displays have a different interface.
Click to expand...

Yes - thinking about it, I vaguely remember a small daughterboard stuck on the back of my display. It was probably an adapter from TTL "rs232" or I2C to the specialised interface on the display itself.

Biggest problem with building this is going to be that the Seatalk bus is on the boat and my computer (a desktop) is at home :D

Pete
 
maby said:
I'm always rather wary about mail-ordering from China...
Click to expand...

No better way of getting electronics hardware!

I tend to buy via eBay, mostly for the wide range of stuff but it does also provide some useful protection. Never heard of anyone having any trouble with this kind of supplier though.

Pete
 
maby said:
Interesting! Have you ordered from them? I'm always rather wary about mail-ordering from China...
Click to expand...

+1

I've bought lots of Ebay items from China. Mainly small stuff, but usually good value. Typically about 2 weeks to arrive, and no hassle with customs as value is pretty small (cheaper than UK almost always)
You sometimes find the same items in the UK (obviously bought in bulk.. and marked up lots for sale here!)

The 3.2" and 5" TFT Touchscreen displays from ITEAD have been good - and I have had good service.
Stuff is impeccably packed. They seem OK.
I'm using them to display wind / groundtrack/ leeway/ etc etc using Arduino processors. Also built power monitoring / water levels/ barometric pressure monitors. None of this is really difficult. Finishing to an acceptable standard is the hard bit...as most people find out :D
 
pagoda said:
+1

I've bought lots of Ebay items from China. Mainly small stuff, but usually good value. Typically about 2 weeks to arrive, and no hassle with customs as value is pretty small (cheaper than UK almost always)
You sometimes find the same items in the UK (obviously bought in bulk.. and marked up lots for sale here!)

The 3.2" and 5" TFT Touchscreen displays from ITEAD have been good - and I have had good service.
Stuff is impeccably packed. They seem OK.
I'm using them to display wind / groundtrack/ leeway/ etc etc using Arduino processors. Also built power monitoring / water levels/ barometric pressure monitors. None of this is really difficult. Finishing to an acceptable standard is the hard bit...as most people find out :D
Click to expand...

Actually, my concern is probably more the safety of giving my credit card details to someone in China - the value of the items in question is minimal and I would not lose sleep over them not arriving. A colleague some years ago did order an expensive item from a supplier in China and never saw either it, or his money again - I would seriously think twice before parting with more than £20 to them!
 
maby said:
Actually, my concern is probably more the safety of giving my credit card details to someone in China
Click to expand...

I never have - all the small suppliers I use go through PayPal. The furthest my details get is Luxembourg :)

PayPal will also refund your money (at least, they will if done through eBay, not sure about otherwise) if the item doesn't turn up or isn't as described. As a company they have done some rather antisocial things in the past, but they do have a useful role as somewhat-trusted mediator for this kind of transaction.

Pete
 
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maby said:
Actually, my concern is probably more the safety of giving my credit card details to someone in China - the value of the items in question is minimal and I would not lose sleep over them not arriving. A colleague some years ago did order an expensive item from a supplier in China and never saw either it, or his money again - I would seriously think twice before parting with more than £20 to them!
Click to expand...

Quite.. the safer solution is PayPal, and many of these companies have realised that they will get extra business if people are comfortable with the transaction. I'm not advertising on their behalf, but it is a very simple way of paying for goods from the other side of the world.
 
maby said:
Actually, my concern is probably more the safety of giving my credit card details to someone in China
Click to expand...
Yes, because all Chinese people are dishonest. Better make sure next time your give you card details to someone in the UK that they are not Chinese.

That was sarcasm by the way.

The bottom line is that if your card is used fraudulently, the card company are liable.
 
Dragged out my PIC stuff from the shed last night and tried to get a "hello world" on the LCD. No joy - although interestingly the panel did nothing at all when power applied, whereas with the interface daughterboard I think it should light up and display a version number, so possibly the thing is dead anyway. The unit is this one, though perhaps an earlier firmware version: http://www.robot-electronics.co.uk/htm/Lcd03tech.htm

Also tried to port the Seatalk stuff to the particular PIC I had - got it compiling but a bit dubious about some of the transpositions I had to make. With no Seatalk bus in my house it's hard to tell if it's working!

Decided I'm not up to making such modifications, and have ordered the parts as specified, to be assembled and programmed as-is. Then maybe I can make progressive changes from a working system :)

Cheers,

Pete
 
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