Add-on board designed for the RC2014 computer to provide an enhanced dual joystick port for games and other applications.
The board is based on a Z80 PIO that provide two 8-bit bi-direction parallel ports. Software can configure each port independently to use a standard Atari-compatibile joystick, a NES-compatible gamepad or any other controller driven by digital I/O lines.
I/O ports can be configured with the on-board dip-switch.
| Parts List | |
|---|---|
| R1 | 10.000 ohm 1/4 watt |
| RN1, RN2 | 10.000 ohm, 9-pin resistor network |
| RN3 | 10.000 ohm, 7-pin resistor network |
| C1, C2 | 100.000 pF polyester |
| IC1 | Z84C2010PEG |
| IC2 | CD74HCT688N |
| S1 | DIP-switch |
| CN1 | 40 pin male header, right angle |
| CN2, CN3 | DB9 male connector |
Additionally, a NES-compatible gamepad board is included for those who don't have access to an existing joystick.
| Parts List | |
|---|---|
| R1-R8 | 10.000 ohm 1/4 watt |
| C1 | 100.000 pF polyester |
| IC1 | CD4021 |
| UP, DOWN, LEFT, RIGHT | 6x6 mm tact switches |
| SELECT, START, B, A | 6x6 mm tact switches |
| CN1 | 5-pin connector |
The Z80 PIO must be initialized at startup by configuring both ports in control mode 3 followed by the pin direction settings appropriate for the game controller type.
Atari 2600 joystick.
PIO_BASE .EQU 70H
; initialize
LD A,0CFH ; set port A mode 3 (control)
OUT (PIO_BASE+1),A
LD A,0FFH ; all pins as input
OUT (PIO_BASE+1),A
LD A,0CFH ; set port B mode 3 (control)
OUT (PIO_BASE+3),A
LD A,0FFH ; all pins as input
OUT (PIO_BASE+3),A
; read joystick 1
IN A,(PIO_BASE)
; read joystick 2
IN A,(PIO_BASE+2)
NES gamepad on Joystick 2.
The code assumes that the gamepad is wired to the DB9 connector as follows: 4=data, 5=load, 6=clk.
PIO_BASE .EQU 70H
NES_LOAD .EQU 20H
NES_CLK .EQU 10H
; initialize
LD A,0CFH ; set port A mode 3 (control)
OUT (PIO_BASE+1),A
LD A,0FFH ; all pins as input
OUT (PIO_BASE+1),A
LD A,0CFH ; set port B mode 3 (control)
OUT (PIO_BASE+3),A
LD A,~(NES_LOAD|NES_CLK) ; clock and load pins as output, others as input
OUT (PIO_BASE+3),A
LD A,0
OUT (PIO_BASE+2),A
; read joystick 1
IN A,(PIO_BASE)
; read joystick 2
LD C,0
LD A,NES_LOAD ; pulse load pin
OUT ((PIO_BASE+2),A
LD A,0
OUT (PIO_BASE+2),A
LD B,8
L1: IN A,(PIO_BASE+2) ; read data from bit 0
RRA
RL C
LD A,NES_CLOCK ; pulse clock
OUT (PIO_BASE+2),A
LD A,0
OUT (PIO_BASE+2),A
DJNZ L1
LD A,C
Boards are shared on OSHPark:
A donation to support this and future projects is always welcome!
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