Recreateing the Apple TechStep

jajan547

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Mar 25, 2022
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Can’t wait. I have two originals, but I’ll buy a new one too. Just out of curiosity will the LCD panel you found fit the old ones? One of mine has a bad lcd panel and I thought I found the right one, but it doesn’t quite work.
Yes it will the new LCDs appear to work with the old and look great!
 
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max1zzz

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Can’t wait. I have two originals, but I’ll buy a new one too. Just out of curiosity will the LCD panel you found fit the old ones? One of mine has a bad lcd panel and I thought I found the right one, but it doesn’t quite work.
yep indeed as @jajan547 says they will work fine however there are a couple of considerations - We are using backlit modules which are a little thicker than the original one, I also haven't seen a module with the exact layout of mounting holes and most modern modules have a different connector position than the original. You'll have to be a little creative but it should work

Also be aware that modern modules require differen't biasing for the contrast control than the techstep uses, the techstep pulls the contrast bias pin on the LCD down to ground through a 1K resistor but most modern modules need a voltage between ground and 5V (or on some modules -5V and +5V) so you'll need to setup a voltage divider for this

For reference, this is the pinout of the LCD connector
1663587069687.png


Most standard 16x4 LCD's should work but this is the specific one I have been using for testing: https://uk.rs-online.com/web/p/lcd-monochrome-displays/8808534
 
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jajan547

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Absolutely going to be putting these on my old TechStepS well at least one because one is starting to get dim. The new one is going to be just absolutely wonderful.
 

max1zzz

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Much progress has been made since the my last post to this thread!

Stage 2 is now more or less complete, All the hardware has been reverse engineered and new boards have been drawn up and sent off for manufacture.
A quick overview of the current status of the hardware:
Logicboard:
1674432025488.png


Port "Pack":
1674432167226.png


Keypad / Power board:
1674432413315.png


These are really "development" versions of the PCB's and will likely be altered a little for the final version but we at a point where we just need to get one of these built and make sure it works!

In particular the keypad PCB needs some attention as that massive 18650 holder will get in the way but I just wanted to PCB mount it so it isn't flapping around while I'm testing. (and I just noticed I have two 8's on the keypad, oops :) )

If I have all my measurements correct these boards should all be able to be stacked and screwed together leaving enough space between the keypad and port pack PCB for the LCD module (Which will sit on a 3D printed bracket) which should make for a rather neat compact solution for testing before we have a case :)
 

jajan547

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Super super excited to see the protos. It’s crazy to think that we Are this close to having this available for multiple people across the world to get the TechStep experience.
 
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Kai Robinson

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Are the 68HC24's a pain to get hold of? I know UTSource supplies them in bulk, but not sure if they're going to be available for long elsewhere - looks like they were EOL'ed in '99?
 
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max1zzz

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Are the 68HC24's a pain to get hold of? I know UTSource supplies them in bulk, but not sure if they're going to be available for long elsewhere - looks like they were EOL'ed in '99?
Yeah they are a a bit of a pain but as @jajan547 says they are available. I'll order some form UTSource (As I need to to a order from them anyway) but they are also available on Aliexpress if you know what to search

The main pain to get is the main microcontroller, I managed to snag a lot of 8 of them for about £12 each last year but these often sell for ~£25 from Chinese suppliers. You can get the OTP parts cheaper but i'm not sure I trust getting OTP arts from china....