deskthority

Well I might put this project on ice until I'm able to get my hands on a working CIT324 terminal (long shot) or another keyboard to do my "please help me out" raffle idea (also long shot). If anyone is interested in taking a crack at it, I'd be happy to ship out this keyboard provided I'd get it back eventually.

Before I go that route I did want to check one more thing. So far I've been doing all these experiments with the keyboard hooked up to the TX pin on the teensy. Is there any potential problem with doing that if the interface is bidirectional? Is it possible that having it hooked up to TX is inhibiting communications in some way?

inb4 the weekend comes and burn yet another day trying to talk to the dead

yeah I could see that mess it up, maybe. But since we really don't know for sure what the physical interface it using, just guesses, it is really hard to tell. Have you confirmed that there are no extra key presses? Being able to send some commands to the keyboard leds is promising, but not conclusive. It could be using that interesting single wire protocol, in which case I don't think the teensy or salece would pick it up properly without building out the single wire split circuit, level shifting back and running it back to two I/O. One thing is pretty clear and that it is not STD fair for a keyboard, Interesting on quite a few levels. I would have a crack at it but US->AU shipping is not kind.

zool wrote: ↑ Have you confirmed that there are no extra key presses?

Yes, I'm 99% sure there are no key presses because even if I detach the membrane it behaves exactly the same.

Well I've clearly lost my mind because I just purchased a CIT326 terminal in hopes that it's compatible (and in hopes that it is resellable)

If this doesn't work out and you're serious about giving it a go zool, I'm sending you the board. Shipping both ways is on me.

THIS IS FREAKING BOARD IS MY EVEREST

snacksthecat wrote: ↑

zool wrote: ↑ Have you confirmed that there are no extra key presses?

Yes, I'm 99% sure there are no key presses because even if I detach the membrane it behaves exactly the same.

Well I've clearly lost my mind because I just purchased a CIT326 terminal in hopes that it's compatible (and in hopes that it is resellable)

If this doesn't work out and you're serious about giving it a go zool, I'm sending you the board. Shipping both ways is on me.

THIS IS FREAKING BOARD IS MY EVEREST

Oh My! Keep on climbing! With a paired terminal, I think you have a good chance at reaching the peak(you will have a Sherpa with you).

But yes, I'm serious, but not until you are exhausted and grasping for breath.

Well the site I ordered the terminal from was ... interesting.

And by "interesting" I mean "had lots of bad reviews".

and by "lots of bad reviews" I mean "almost exclusively really horrible reviews"

hope this works out

Until then, cheers boys

Well it's two weeks since I placed my order and still radio silence from the vendor -- apart from the confirmation email I got immediately after the purchase. I've come to accept that this thing is never getting delivered to me.

Exhibit A: Their contact page...
...lists AIM as one method of getting a hold of them. AIM no longer exist. Even when it existed, it's still pretty suspect. Exhibit B: They have a 1 star TrustPilot rating
This would be great if TrustPilot worked like the Michelin system. Unfortunately, they are not a restaurant but a reseller of old electronics. I actually don't know anything about TrustPilot but I found this pretty funny. Exhibit C: Yelp reviews
They all pretty much go like this:

Placed an online order on 9/7. No reply until I sent a followup email on 9/15 only to be informed the item was back-ordered and they expected a shipment in the next 5 business days. Authorized the purchase on 9/16 based on this expectation only to see 5 days come and go AGAIN with no response/update. Sent a followup email on 9/29 and have not heard anything from anyone! It's been nearly 4 weeks and I just contacted my credit card company to start dispute proceedings. Is THIS what you call customer service? I'm amazed they're even in business...BUYER BEWARE!

or this...

I have to say this is a scam company. They never respond to emails, and ultimately they never deliver the merchandise. Thankfully I paid through American Express and had the charge reversed. AVOID DOING ANY BUSINESS WITH THIS COMPANY!

Exhibit D: Common sense
Clearly I have none

I busted this board out again because I've been bored with everything else (no pun intended).

I was reading up on the datasheet [1] for the main IC (P8049AH) on the train and found this nugget that explains the "read" operation that this description of my one data pin.



So I tried to produce this RD strobe which is explained as 480 nanoseconds here:



and has an accompanying waveform here:



Much to my surprise, if I hold a key and send the RD interrupt signal, I sometimes get the keyboard to send me the ascii character of the key I'm pressing (sent at 4800 baud).

Here's what it looks like if I do this while pressing "k"



[1] https://www.datasheets360.com/pdf/-8876873277551500615

This is the first and only bit of success that I've had with this keyboard in a year of trying and an uncountable number of hours spent tinkering with it!!!

Now we're cooking with peanut oil, boys.
I wrote a little arduino sketch that repeatedly sends the ~480ns interrupt and prints the output from the keyboard to the serial monitor.

It seems that the keyboard sends ascii codes at 4800 baud for the make codes and then for the break codes it sends the ascii code + 128. Some keys behave slightly differently like the modifiers and the return key.

Now that I know how the board works, I think this will make a great little conversion project where I can hone my very beginner-ish AVR skills.

Might need to desolder that clicker first though!

Nice work! Agree, that clicker is a bit much.