A few weeks ago i designed a print using Kicad.
Today they have arrived!
Now I have to wait a little more .. A 74HTC166 and a straightup RCA connector.
I the past, a long time ago i made my own single side pcb’s using acids.
A messy job, often gone wrong.
Old skool example https://www.youtube.com/watch?v=_PwCp3A3RSk
Or https://www.circuitsonline.net/artikelen/view/1/print
I started to get some composite video generated with a arduino for my 6502 project.
UPDATE: 20221021
It is based on Grant Searle’s design, and yesterday I had some signals on my scope which looked like a screen with a character. But my monitor would not recognize a usable signal.
Today I tried a second version and another set of chips and crystals.
It looks like a signal, but I can’t see a clock pulse from the crystal?! So .. how?
Maybe I used a bad power supply. And killed something?
UPDATE: 20221021
After switching to another power supply, and checking the atmega328p fuses again (also wrong) .. at least SOME success!
Some minipro info #Erase minipro -p ATMEGA328P@DIP28 -E #Flash hex code minipro -p ATMEGA328P@DIP28 -w SBCVideo.hex #Flash fuses minipro -p ATMEGA328P@DIP28 -e -c config -w fuses #Used fuses file lfuse = 0xf7 hfuse = 0xd9 efuse = 0xfc lock = 0xff lfuse = 0xff hfuse = 0xff efuse = 0xff user_id0 = 0xff user_id1 = 0xff user_id2 = 0xff user_id3 = 0xff user_id4 = 0x37 user_id5 = 0x37 user_id6 = 0x39 user_id7 = 0x36 #Dump all from atmega328p minipro -p ATMEGA328P@DIP28 -r dump -f ihex
Some info about the fuses:
https://www.allaboutcircuits.com/projects/atmega328p-fuse-bits-and-an-external-crystal-oscillator
There are a lot of old develop boards for all kinds for cpu’s.
These where build to learn machine code programming. Mostly made in the 80’s, and based on populair cpu’s at that time.
I own a some of these SDK’s (System Design Kits)
Most of these use a keyboard scanner which is also connected to 7 segment displays.
The way they work is practically the same. There is a VIA or PIA. Versitile interface adaptor, or Peripheral interface adaptor. These have two times 8 bits to control devices.
When using 4 bits and convert these to 16 lines by using a 75ls145 for example. If you put a counter on those 4 bits, you sequently activate 1 of 16 lines. These lines you can use to scan a keyboard matrix OR display a character on a 7 segment display. These display’s won’t hold the data (and show the character) when not activated. The trick is to update de display fast enough so you don’t see the flickering on/off.
Activate a line and read a byte with the VIA = Reading keyboard row
Activate a line and write a byte with the VIA = Display on a segment
These VIA/PIA’s where made with specific timings to match the CPU.
6522/6820/8255
Below you see some different implementations of these keyboard/display combo’s
When looking at the 8085 version you see transistors being a ULN2003 is a chip with those transistors/amplification enclosed.
It doesn´t draw much current from the bus, and diodes protect the way the current flows.
I only have to check my new design for a generic matrix keyboard once again, and then i’m going to order a few of these prints.
I’ve used the opensource tool freeroute to autoroute the coppertraces
TODO: Look into charlieplexing ! For input and Led control
Work in progress code
PORT2B = $5000 ; VIA PORTB PORT2A = $5001 ; VIA PORTA DDR2B = $5002 ; Data direction register DDR2A = $5003 ; Data direction register PORTB = $6000 ; display PORTA = $6001 ; control display + matrix keyboard DDRB = $6002 ; data direction register DDRA = $6003 ; data direction register SID = $7000 ; sid base address E = %10000000 ; enable bit RW = %01000000 ; RW bit RS = %00100000 ; Register Select bit HOME = %00000010 ; VIA PORTB HOME command DADDR = %00010000 ; VIA DADDRESS LINENO = $0200 ; temp address linenumber (move to other location) NEXTLINE = 40 ; 2x16 Chars but internally 40 .org $8000 reset: ldx #$ff txs ; reset stack ; ################################################### ; # DISPLAY CONTROL # ; ################################################### ; VIA Setup lda #%11111111 ; Set all pins on port B to output sta DDRB lda #%11100000 ; Set top 3 pins on port A to output sta DDRA ; DISPLAY Setup lda #%00111000 ; Set 8-bit mode; 2-line display; 5x8 font jsr lcd_instruction lda #%00001110 ; Display on; cursor on; blink off jsr lcd_instruction lda #%00000110 ; Increment and shift cursor; don't shift display jsr lcd_instruction lda #$00000001 ; Clear display jsr lcd_instruction ; ################################################### ; # PRINT MESSAGE LINE NO 0 # ; ################################################### lda #0 ; set line number sta LINENO ; store for subroutine jsr gotoline ; move cursor ldx #0 ; message index pointer print: lda message0,x ; start of message beq nextprint ; stop when null in message (asciiz <- Zero padded) jsr print_char ; print char inx ; incr index jmp print ; resume print ; ################################################### ; # PRINT MESSAGE LINE NO 1 # ; ################################################### nextprint: lda #1 ; set line number sta LINENO ; store jsr gotoline ldx #0 ; index pointer print2: lda message1,x ; absolute address message + x in A beq sidsound ; if x is 0, end of message jsr print_char ; jump subroutine inx ; increment x jmp print2 ; loop print2 ; ################################################### ; # SID SOUND # ; ################################################### sidsound: lda #0 sta SID+$5 ; attack/decay duration lda #250 sta SID+$6 ; sustain level/release duration lda #$95 ; frequency voice 1 low byte sta SID+$0 lda #$44 ; frequency voice 1 high byte sta SID+$1 lda #%00100001 ; sawtooth + gate sta SID+$4 ; control register voice 1 lda #$0f ; filter mode and volume (bits 3-0 main volume) sta SID+$18 ; filter mode and volume ; ################################################### ; # 2ND VIA # ; ################################################### lda #%11111111 ; set port A output sta DDR2A lda #%11111111 ; all ones! sta PORT2A ; ################################################### lda #%11111111 ; set port A output sta DDR2A lda #%11111111 ; all ones! sta PORT2A ; ################################################### ; # MAIN PROGRAM LOOP # ; ################################################### loop: jmp loop ; 1234567812345678 message0: .asciiz "VIA 1,2 SID TEST" message1: .asciiz " FASH 2022 " ; ################################################### ; # ONLY SUBROUTINES # ; ################################################### ; ################################################### ; # Subroutine gotoline # ; # Moves character placement position on display # ; # Needs : $LINENO ADDRESS # ; # Exit values : - # ; # Destroys registers: - # ; ################################################### gotoline: pha ; store a txa pha ; store x ldx LINENO lda #HOME ; cursor down jsr lcd_instruction lda #$80 nextline: ldx LINENO cpx #00 beq endnextlines loopline: adc #40 jsr lcd_instruction dex stx LINENO jmp nextline endnextlines: pla ; pop a tax ; a to x pla ; pop a rts ; ################################################### ; # LCD SUBROUTINES # ; ################################################### lcd_wait: pha lda #%00000000 ; Port B is input sta DDRB lcdbusy: lda #RW sta PORTA lda #(RW | E) sta PORTA lda PORTB and #%10000000 bne lcdbusy lda #RW sta PORTA lda #%11111111 ; Port B is output sta DDRB pla rts lcd_instruction: jsr lcd_wait sta PORTB lda #0 ; Clear RS/RW/E bits sta PORTA lda #E ; Set E bit to send instruction sta PORTA lda #0 ; Clear RS/RW/E bits sta PORTA rts print_char: jsr lcd_wait sta PORTB lda #RS ; Set RS; Clear RW/E bits sta PORTA lda #(RS | E) ; Set E bit to send instruction sta PORTA lda #RS ; Clear E bits sta PORTA rts nmi: rti irq: rti .org $fffa .word nmi .word reset .word irq ; .word $0000
As previously posted, i had an idea to create a dual matrix keyboard mashup using available components.
I mentioned that “it should theoretically work”. But only being using atf22v10c for a couple of days. It was a long shot.
I’ve put it to the test .. and it worked first time.
I can use above, to connect my extended matrix keyboard to a 6522 VIA chip using 5 pins and sending a data available signal to CA1.
In this case designed for my 6502, but it is a generic setup.
I it just a dual 16key matrix decoder merged together. You can probably use this with raspberries, arduinos etc.
I wanted to use 74C923 but these are nowhere to be found. And even then, the number of keys wil be 20.
So i am tying together two 74C922 using some logic in a PLD.
It wil be something like above. Using the data availabe signal i can combine both 16key matrixes. (In theory .. it is all untested)
PLD Code
GAL22V10 Address Decoder PHI2 DA0 DA1 D01 D02 D03 D04 D11 D12 D13 D14 GND NC D0 D1 D2 D3 D4 DA NC NC NC NC VCC DA = DA0 + DA1 D0 = D01 & DA0 + D11 & DA1 D1 = D02 & DA0 + D12 & DA1 D2 = D03 & DA0 + D13 & DA1 D3 = D04 & DA0 + D14 & DA1 D4 = DA1 DESCRIPTION Key matrix merger
I’ve got my new keys of the keyboard in today!
My inkscape template (keys are 10/10mm)
Printed on white and red paper
https://media.henriaanstoot.nl/keyboardmatrix.svg
New address decoder in place!
Connected RAM/ROM/SID/VIA1/VIA2 and ACIA
| ROM | 8000-FFFF |
| SID | 7000-700F (sound) |
| VIA1 | 6000-60xx (Hex key matrix) |
| ACIA | 6800-68xx (serial) |
| VIA2 | 5000-50xx (led test at the moment) |
| RAM | 0000-3FFF |
To plan: Bigger maxtrix keyboard and other displays
Got a serial connection working between the 6502 and my linux machine!
At the moment when a reset occurs , hello is being printed.
Text typed in the minicom terminal, is echo-ed back and displayed on the LCD display.
Things learned: Do not trust internet schematics blindly!
The crystal used for the ACIA (pin 6/7 1.8432Mhz needs a 1M ohm resistor parallel over the crystal, and a 30nF capacitor from pin 7 to GND
When using a terminal emulator, and using 3 wires. Disable hardware handshake.
What didn´t work as planned:
New amplifier schematic for the SID. There is too much noise.
Bought a dual power supply (5V and 12V). But this one has a lot of signal noise on the SID part and even my battlestation speakers!
LED test 2nd via
PORTB = $5000 ; VIA PORTB PORTA = $5001 ; VIA PORTA DDRB = $5002 ; Data direction register DDRA = $5003 ; Data direction register LED = %10000000 .org $8000 reset: lda #%11100000 ; Set top 3 pins on port A to output sta DDRA lda LED sta PORTA loop: ; done loop until doomsday jmp loop irq: nmi: .org $fffa .word nmi .word reset .word irq
ACIA part
ACIA_RX = $6800
ACIA_TX = $6800
ACIA_STATUS = $6801
ACIA_COMMAND = $6802
ACIA_CONTROL = $6803
lda #$00
sta ACIA_STATUS
lda #$0b
sta ACIA_COMMAND
lda #$1f
sta ACIA_CONTROL
The ATF22V10 is a Programmable Logic Device. This means you can program the logic in the chip.
Internally it looks like a big matrix of connections which you can program to connect/disconnect from certain logic.
It has just a bunch of inputs/outputs
So if we want to have a 7 Segment decoder (you can easily buy a BCD decoder .. but these only work for displaying 0-9 and not 0-9A-F for displaying HEX numbers)
| Binary IN | 7 Segment decoded | Displays |
| D C B A | A B C D E F G | |
| 0 0 0 0 | 1 1 1 1 1 1 0 | 0 |
| 0 0 0 1 | 0 1 1 0 0 0 0 | 1 |
| 0 0 1 0 | 1 1 0 1 1 0 1 | 2 |
| 0 0 1 1 | 1 1 1 1 0 0 1 | 3 |
| 0 1 0 0 | 0 1 1 0 0 1 1 | 4 |
| 0 1 0 1 | 1 0 1 1 0 1 1 | 5 |
| 0 1 1 0 | 1 0 1 1 1 1 1 | 6 |
| 0 1 1 1 | 1 1 1 0 0 0 0 | 7 |
| 1 0 0 0 | 1 1 1 1 1 1 1 | 8 |
| 1 0 0 1 | 1 1 1 1 0 1 1 | 9 |
| 1 0 1 0 | 1 1 1 0 1 1 1 | A |
| 1 0 1 1 | 0 0 1 1 1 1 1 | B |
| 1 1 0 0 | 1 0 0 1 1 1 0 | C |
| 1 1 0 1 | 0 1 1 1 1 0 1 | D |
| 1 1 1 0 | 1 0 0 1 1 1 1 | E |
| 1 1 1 1 | 1 0 0 0 1 1 1 | F |
Now we see that segment A is 1 in the case of (0,2,3,5,6,7,8,9,A,C,E,F)
When programming the PLD we can write that as: (note / means inverted a plus is OR, and * is AND)
So A is 0 in case of input being (1,4,B,D)
/QA = /D1 * /C1 * /B1 * A1
+ /D1 * C1 * /B1 * /A1
+ D1 * /C1 * B1 * A1
+ D1 * C1 * /B1 * A1Complete code for galasm
Compiling and burning
GAL22V10
7SEGMENT
Clock D1 C1 B1 A1 D2 C2 B2 A2 NC NC GND
/OE NC NC NC QG QF QE QD QC QB QA VCC
/QA = /D1 * /C1 * /B1 * A1
+ /D1 * C1 * /B1 * /A1
+ D1 * /C1 * B1 * A1
+ D1 * C1 * /B1 * A1
/QB= /D1 * C1 * /B1 * A1
+ /D1 * C1 * B1 * /A1
+ D1 * /C1 * B1 * A1
+ D1 * C1 * /B1 * /A1
+ D1 * C1 * B1 * /A1
+ D1 * C1 * B1 * A1
/QC = /D1 * /C1 * B1 * /A1
+ D1 * C1 * /B1 * /A1
+ D1 * C1 * B1 * /A1
+ D1 * C1 * B1 * A1
/QD= /D1 * /C1* /B1 * A1
+ /D1 * C1 * /B1 * /A1
+ /D1 * C1 * B1 * A1
+ D1 * /C1 * B1 * /A1
+ D1 * C1 * B1 * A1
/QE = /D1 * /C1 * /B1 * A1
+ /D1 * /C1 * B1 * A1
+ /D1 * C1 * /B1 * /A1
+ /D1 * C1 * /B1 * A1
+ /D1 * C1 * B1 * A1
+ D1 * /C1 * /B1 * A1
/QF = /D1 * /C1 * /B1 * A1
+ /D1 * /C1 * B1 * /A1
+ /D1 * /C1 * B1 * A1
+ /D1 * C1 * B1 * A1
+ D1 * C1 * /B1 * A1
/QG = /D1 * /C1 * /B1 * /A1
+ /D1 * /C1 * /B1 * A1
+ /D1 * C1 * B1 * A1
+ D1 * C1 * /B1 * /A1
DESCRIPTION
A 7 segment hex decoder
galasm 7seghex.gal
minipro -p ATF22V10CQZ -w 7seghex.jed
minipro -p ATF22V10CQZ -w 7seghex.jed Found TL866II+ 04.2.129 (0x281) Warning: Firmware is newer than expected. Expected 04.2.128 (0x280) Found 04.2.129 (0x281) VPP=12V Warning! JED file doesn't match the selected device! Declared fuse checksum: 0x98D5 Calculated: 0x98D5 ... OK Declared file checksum: 0x40B3 Calculated: 0x41A8 ... Mismatch! JED file parsed OK Use -P to skip write protect Erasing... 0.33Sec OK Writing jedec file... 5.01Sec OK Reading device... 0.32Sec OK Writing lock bit... 0.35Sec OK Verification failed at address 0x16C6: File=0x01, Device=0x00 < ------------------ Gives error, but burning seems okay henri@zspot:~/projects/galasm$ minipro -p ATF22V10CQZ -r 7seghex.out Found TL866II+ 04.2.129 (0x281) Warning: Firmware is newer than expected. Expected 04.2.128 (0x280) Found 04.2.129 (0x281) Reading device... 0.32Sec OK Gives all zeros as output, but device works!
Made a simulation of my new address decoder.
It uses a 74LS138 and a bunch of NAND gates.
You can safe using 4 NAND gates if you are not going to use split IO
| Address | ||
| 8000-FFFF | ROM | ROM |
| 7000-7FFF | Sound chip | SID |
| 6000-6FFF | Display + cursor | VIA1 |
| 5000-5FFF | Keymatrix | VIA2 |
| 4800-4FFF | split io | IO |
| 4000-47FF | split io | IO – ACIA |
| 0000-3FFF | Uses clock | RAM |
UPDATE: Found some 74LS139, so i could have changed some things around.
Try it over here: