Author Topic: z80-like portable computer for <$30! (If you build one)  (Read 53909 times)

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Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #60 on: July 24, 2013, 05:13:56 am »
The pressure is on. I will be working on the tutorial again as soon as I have written some more example code.

Edit: I updated the tutorial. http://8times8.host56.com/ez8tut.html
« Last Edit: July 24, 2013, 05:40:07 pm by Keoni29 »
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Offline willrandship

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #61 on: July 30, 2013, 12:00:53 am »
Today I half-finished an opcode reference for the ez8. It's on Keoni's site, right here.

http://8times8.host56.com/ez8tut/reference/Opcodes.php

I'm planning on adding another part to it detailing the exact effects of every opcode by its hex value, but for now that should do.

Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #62 on: July 30, 2013, 05:05:24 am »
We think Zilog should hop onto the Maker train and support creative minds. They are not doing this at the moment which is a shame because they already have nice devboards that don't cost a lot. The main problem is the lack of tutorials on how to program for their eZ8 microcontroller. That's why we started building our own tutorial and programmers reference.

There is one major hurdle to overcome when you want to get into eZ8 programming and that is the Zilog SmartCable. You need one of these or else it won't work with the IDE. The communication protocol with the debug interface (which you use to program the chip with) is fairly standard TTL level UART (rs232 serial, but 3V/5V levels) A normal usb to TTL converter does not work with their IDE as we tested. The cable is hard to get for a fair price. They go for about $30 and shipping is expensive. The eZ8 itself is a really cheap microcontroller at $6 for the most powerful 64k flash model and around $3 for a 16k flash version.

We hope that our website will encourage people to start programming for the eZ8. I try to be on #zilog on EFnet as often as possible.

I think most of you already know how to get to our website (I posted the link in IRC a quite often), but those of you who don't: http://www.8times8.host56.com/ez8tut
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Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #63 on: August 05, 2013, 04:46:09 pm »
There has been quite an overhaul to the tutorial pages. For starters: the tutorial now has a dedidated website: http://ez8tut.sourceforge.net/
It contains more than just the ASM programming tutorial. There is a reference for programming and for the CPU and peripherals. There will also be resources such as example code, routines and user submitted content. I am in the process of creating a CMS
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Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #64 on: August 08, 2013, 08:58:37 am »
I'm almost able to interface with my lcd display. I have to put a lot of delay in the program since it is a really slow display. When I step trough the program in debug mode it works find and I can initialize the LCD module and put characters on it :D
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Offline Streetwalrus

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #65 on: August 08, 2013, 01:36:01 pm »
Nice to hear it's coming alive. :D

Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #66 on: August 09, 2013, 06:04:30 am »
Allright! It works now. I think it works with all character displays since the delays are super long :P

Edit: Oh I see there is a little bit of a bug in my example program: Line 2 appears on line 3 and line 3 appears on line 2. This is because of how the driver works. No real problem here.
« Last Edit: August 09, 2013, 06:07:01 am by Keoni29 »
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Offline TIfanx1999

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #67 on: August 09, 2013, 07:59:59 am »
Very nice Keoni! :D

Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #68 on: August 09, 2013, 04:15:11 pm »
It is a bit annoying how the lcd puts those lines in the wrong place. That way you have to manually keep track of where your cursor is or read from the display every time you check if it should do a line wrap. I guess that is what you get for using a driver that has been designed for driving 1 and 2 line displays.
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Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #69 on: August 10, 2013, 04:53:15 am »
This little trick is achieved by using custom characters. It is an 8x8 sprite on a 20x4 character display. To resemble my logo I had to put an empty line in the double pixel character, so it is a little bit off, but it looks allright I guess.
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Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #70 on: August 11, 2013, 11:46:51 am »
http://ez8tut.sourceforge.net/highlighter.php/
I wrote a syntax highlighter for eZ8 syntax. It exports to html and BB forumcode. Example:
include "ez8.inc"

vector reset = 1000h
org 1000h

main:
   di         ;Disable interrupts as we won't be using them
   srp #00h      ;Set working registers base address (Working registers are R0-R15)
   ldx SPH,#00h      ;Set stack pointer base address
   ldx SPL,#FFh      ;(the stack is 00ffh - 0000h so 256 bytes large)
   
   ldx PAADDR, #01h   ;Access the data direction subregister
   ldx PACTL,#00h      ;Set data direction of port B to all outputs. 0 = output, 1 = input
   ld  R4,   #77h      ;Load register R0 with EEh. This will be our rotated value.
   brk         ;Breakpoint. The debugger will stop the cpu here.Press the go button to
            ;continue execution.
loop:
   ldx PAOUT, R4      ;Load the output register of port B with the value of our counter.
   rr R4         ;Increase our counter by 1.   
   call delay      ;Call our delay function.
   jp loop         ;Jump back to loop
delay:
      
   ld R0,#0Fh      ;Load value 0FFFh in the 16 bit register pair RR0 (consists of R0 and R1)
   ld R1,#FFh
outer:
   ld R2,#FFh      ;Load value 0FFh in 8 bit register R2

   djnz R2,$      ;Decrease
   decw RR0
   jp nz, outer      ;While the register pair has not reached 0 (nz) yet jump back to outer
   ret         ;Return from routine


There is a bug in omnimaga's stylesheet that causes the preformatted text to look different from normal pre tags apparently since this should format right.
« Last Edit: August 11, 2013, 12:20:09 pm by Keoni29 »
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Offline DJ Omnimaga

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #71 on: August 16, 2013, 07:38:46 pm »
Wow I like it so far Keoni29 :D
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Offline willrandship

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #72 on: August 16, 2013, 09:17:09 pm »
We're currently discussing using a parallax propeller to handle various I/O tasks, including hardware-generated VGA/Composite video. While the propeller works on handling the various I/O devices like the SD card, keyboard, video, audio, etc., the ez8 has plenty of time to run user programs.

Offline Keoni29

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #73 on: August 17, 2013, 09:51:04 am »
I am a complete noob with propeller chip, but I managed to combine two programs: the TV terminal library and the Serial library. I made a serial terminal :) At the moment it is one way. I have not hooked up a keyboard to the propeller yet.
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Offline aeTIos

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Re: z80-like portable computer for <$30! (If you build one)
« Reply #74 on: August 17, 2013, 01:48:03 pm »
So how far is this from being build-ready? I'd like to solder this thing together :3
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