The complete system list at least for while

I am not so organized  but am so confident to write down the topics of my project after I already started it.
They are a sketch by this they can change any time.

1 - The z80 clock
2 - Addressing system
3 - Static memory(SRAM) 32kbytes minimal
4 - Eprom memory(8kbytes)
5 - I/O system(bip sound, rs232, spi interface)
6 - SDcard (at least 8gb)
7 - keyboard and 6 display 7 segments and LCD maybe 4lines 20 characters
8 - CPU Z80 8Mhz and I/O expansion bus

The z80 clock

My z80 system will be started in a section named, the clock, that I had so many doubts about it, as I used to work with moderns microcontrollers and clock does not need to be so clear, and I read that z80 needs a clean clock and reset, I decided to use an attiny15L that I have some pieces here.

This chip will provide  several clocks for the system and configuring 2 pins it is possible to change betwen them. The clock values are:

12Mhz, 6Mhz, 3Mhz and 1,6Mhz no need to say that all of them will not have the precise value, because the attiny15l has a pll that generate 25Mhz that is divided to get these values

Another feature is:

1 - the reset pulse to the z80, this reset will maintain the z80 for a long time in logic level zero when the power supply is turned on.

2 -  led blinking, this is just to sinalize that the system is on,

Image 01 - Clock

Attiny15L - Assembler code to generate: clock, reset and blink led

; Program....: reset.asm

; Description: Z80 reset, clock 1,6Mhz, 3,2Mhz, 6,4Mhz or 12,8Mhz

; Author.....: Paulo da Silva

; Date.......: 26/09/2016

; 

; Attiny15L

;       +----+

;  rst--|    |-- vcc;

; cfg1 --|    |-- led blink

; cfg2 --|    |-- z80 clock

;  gnd--|    |-- z80 reset

;       +----+

;                                           

;    cfg2 cfg1                                      

;     0    0  ->   12,8Mhz                           

;     0    1  ->    6,4Mhz                  

;     1    0  ->    3,2Mhz                      

;     1    1  ->    1,6Mhz   

;

; Assembler: avra version 1.3.0 build 1

; Command..: avra reset.asm

.nolist

.include "/usr/share/avra/tn15def.inc"

.list

;==============

; Declarations

; PB0 - reset for z80

; PB1 - z80`s clock

; PB2 - led blink

; PB3 - Clock`s Configuration bit 1 (cfg1)

; PB4 - Clock`s Configuration bit 2 (cfg2)

;=================

; Variable Declarations

.equ OSCCAL_val = 0x6F ; Calibrate

.def cseg       = r21

.cseg ; Code segment.

; Start of Program

.org    0

rjmp Init ; First line executed

reti ; IRQ0 handler

reti ; Pin change handler

rjmp timer1CM ; Timer1 compare match

reti ; Timer1 overflow handler

rjmp timer0; ; Timer0 overflow handler    

reti ; Eeprom Ready handler

reti ; Analog Comparator handler

reti ; ADC Conversion Handler

;============

Init:

; writing calibration byte to the OSCCAL Register.

ldi     r16, OSCCAL_val

out     OSCCAL, r16       

nop

nop

;Analogue comparator initialization

ldi      r16, 0b10000000 ; Disable analogue comparator

out      ACSR, r16

;PORTB initialization

ldi      r16, 0b00000111 ; 1 = output e 0 =input1/6

out      DDRB, r16 ; pb0 and pb1 = output pb2 = input

ldi      r16, 0b11111000

out      PortB, r16

;Timer initialization

ldi      r16, 0x05 ; Timer 0 rolls over at 1.6MHz/1024/256 = 6.1Hz

out      TCCR0, r16

;timer 1

in r16, PinB ; Input port b to read clock configuration

andi r16, 0b00011000 ; pb3 and pb4

cpi r16, 0b00000000 ; 00 = 12,847Mhz

brne test6mhz

ldi r16, 0b10010001 ; 12Mhz

    rjmp init2

test6mhz:

cpi r16, 0b00001000 ; 01 = 6Mhz

brne test3mhz

ldi r16, 0b10010010 ; 6,396 Mhz

rjmp init2

test3mhz:

cpi r16, 0b00010000 ; 10 = 3Mhz

brne test1mhz

ldi r16, 0b10010011 ; 3,210Mhz

rjmp init2

test1mhz:

ldi r16, 0b10010100 ; 1,605Mhz

init2:

out TCCR1, r16

ldi r16, 0b00000000

out TCNT1, r16

ldi      r16, $02 ;  Enable TOVF0

out      TIMSK, r16

ldi      cseg, $01 ; Start at segment

ldi      r17, 0x00

ldi      r16, 0x00

sei                 ; Enable Interrupts          

;======================

; Main body of program:

Main:            

loopRst:

cbi PortB, pb0

cpi r16, 6 ; Wait some time here before to raise z80's reset line 

brne loopRst

sbi PortB, pb0

blink:

;blink a led

SBRS    r16, 0 ;2 Skip next instruction if bit0 = 1

SBI    PORTB, pb2 ;2 Turn LED ON if bit0 = 0

SBRC    r16, 0 ;2 Skip next instruction if bit0 = 0

CBI    PORTB, pb2 ;2 Turn LED OFF if bit0 = 1

rjmp    blink ;2 loops back to the start of Main

timer0:

inc r16 ;Increment and will be used to blink a led

reti

    

timer1CM:

This is tested !!!

:) Enjoy

Greetings !!

Hi all,

Wecome to my blog!

It is the first time that I will share my things, so I hope you enjoy all of them.

Here I'll try to publish all my projects of hardware and software, specially the embedded one.
My first project is a z80 system made by me, I know that outside there has a lot of this kind of project but mine is a long time desire,since I was attending an electronic technician course so don't blame me to realize it.

:) Enjoy !!!