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Gameboy RS 232 interfacing
; Taken from: https://fruttenboel.verhoeven272.nl/Gameboy/GBrs232.html
;***********************************
;* RS232 9600,n,8,1 *
;* *
;* through serial port *
;* *
;* Ken Kaarvik May21/99 *
;* *
;***********************************
;Talk to a RS232 device at 9800,n,8,1
;
;Pin outs - wire through a MAX-232
;
;CGB MAX-232 9pin serial
; port on computer
; +5V-----------+---+
; | |
; 16 =
; | |+
; | |
; |~~~~~~~~|
; | 16 2 |
; | |
;< Pin 4------|12 13|------3 <
;> Sout-------|11 14|------2 >
; | |
; +--|4 1|--+
; +| | | |+
; = | | =
; | | | |
; +--|5 3|--+
; | |
; |__15__6_|
; | |
; | =
; | |+
; gnd-----------+---+--------5
;
; (4) caps @10uF Note polarity
;
display_col equ $9800
blank equ 16
text_line equ $9800+$20*5
SECTION "Org $0", HOME
ret
; Button Push Interrupt - For sending out data while waiting for input
SECTION "Org $60",HOME[$60]
push af
call pad_Read
call send_test
xor a
ldh [$00],a
pop af
reti
INCLUDE "hardware.inc"
INCLUDE "ibmpc1.inc"
SECTION "Header",HOME[$0100]
nop
jp Startup
DB $CE,$ED,$66,$66,$CC,$0D,$00,$0B,$03,$73,$00,$83,$00,$0C,$00,$0D
DB $00,$08,$11,$1F,$88,$89,$00,$0E,$DC,$CC,$6E,$E6,$DD,$DD,$D9,$99
DB $BB,$BB,$67,$63,$6E,$0E,$EC,$CC,$DD,$DC,$99,$9F,$BB,$B9,$33,$3E
;0123456789ABCDE
DB "RS232 "
DB $80 ; $80=Color GB
DB 0,0,0 ; SuperGameboy
DB 0 ; CARTTYPE
; --------
; 0 - ROM ONLY
; 1 - ROM+MBC1
; 2 - ROM+MBC1+RAM
; 3 - ROM+MBC1+RAM+BATTERY
; 5 - ROM+MBC2
; 6 - ROM+MBC2+BATTERY
DB 0 ; ROMSIZE
; -------
; 0 - 256 kBit ( 32 kByte, 2 banks)
; 1 - 512 kBit ( 64 kByte, 4 banks)
; 2 - 1 MBit (128 kByte, 8 banks)
; 3 - 2 MBit (256 kByte, 16 banks)
; 3 - 4 MBit (512 kByte, 32 banks)
DB 0 ; RAMSIZE
; -------
; 0 - NONE
; 1 - 16 kBit ( 2 kByte, 1 bank )
; 2 - 64 kBit ( 8 kByte, 1 bank )
; 3 - 256 kBit (32 kByte, 4 banks)
DW $0000 ; Manufacturer
DB 0 ; Version
DB 0 ; Complement check
DW 0 ; Checksum
INCLUDE "memory1.asm"
INCLUDE "keypad.asm"
SECTION "Main",home[$0150]
Startup
call initialize
Main
call inc_counter
call read_rs232
call wait_vb
call write_to_screen
jp Main
send_test
ld a,[_PadDataEdge] ; _PadData]
cp 0
ret z
cp PADF_A
jp z, service_button_a
cp PADF_B
jp z, service_button_b
cp PADF_START
jp z, service_start
cp PADF_SELECT
jp z, service_select
cp PADF_UP
jp z, service_up
cp PADF_DOWN
jp z, service_down
cp PADF_LEFT
jp z, service_left
cp PADF_RIGHT
jp z, service_right
ret
service_button_a
ld hl, a_button_text
call send_text
ret
service_button_b
ld hl, b_button_text
call send_text
ret
service_start
ld hl, start_text
call send_text
ret
service_select
ld hl, select_text
call send_text
ret
service_up
ld hl, up_text
call send_text
ret
service_down
ld hl, down_text
call send_text
ret
service_left
ld hl, left_text
call send_text
ret
service_right
ld hl, right_text
call send_text
ret
send_text
ld a, [hl+]
cp $80
ret z
ld b, a
call send_rs232
jp send_text
a_button_text
db "You pressed the A button ", $80
b_button_text
db "Hello world I pressed B ", $80
start_text
db "Start ", $80
select_text
db "Select ",$80
up_text
db "Up ", $80
down_text
db "Down ", $80
left_text
db "Left ", $80
right_text
db "Right ", $80
title_text
db "RS232 send & receive"
clear_ram
ld a, blank
ld hl, raw_data
ld bc, 36
call mem_Set
ret
read_rs232 ; read in byte at pin4
ld b, $80 ; $01
ei
wait_for_start_bit
ldh a, [$56]
bit 4, a
jp nz, wait_for_start_bit
di
call delay_130us
read_next_bit
ldh a, [$56]
swap a
rr a ; put pin 4 into carry
rr b
jp c, wait_for_stop_bit
call delay_104us
jp read_next_bit
wait_for_stop_bit
call delay_104us
call delay_104us
wait_for_after_stop_bit
ld a, b
ld [raw_data], a
ret
send_rs232 ; send byte in B out Sout
ld e, 8
ld a, 0 ; send start bit
ldh [$01], a
ld a, $83
ldh [$02], a
call delay_104us_send
send_next_bit
rr b
ld a, 0
jp nc, keep_it_zero
ld a, $FF
keep_it_zero
ldh [$01], a
ld a, $83
ldh [$02], a
call delay_104us_send
dec e
jp nz, send_next_bit
ld a, $FF ; send stop bit
ldh [$01], a
ld a, $83
ldh [$02], a
call delay_104us_send
ret
delay_130us
ld d, 23
d130 dec d
jp nz, d130
ret
delay_104us
ld d, 17
d104 dec d
jp nz, d104
ret
delay_104us_send
ld d, 16
d104s dec d
jp nz, d104s
ret
inc_counter
ld a, [counter]
inc a
ld [counter], a
ret
write_to_screen
call shift_display_left
ld a, [raw_data]
ld hl, text_line+19
call display_char
ld de, counter
ld hl, display_col+$20*3
call display_byte
ret
shift_display_left
ld hl, text_line+1
ld de, text_line
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+2
ld de, text_line+1
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+3
ld de, text_line+2
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+4
ld de, text_line+3
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+5
ld de, text_line+4
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+6
ld de, text_line+5
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+7
ld de, text_line+6
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+8
ld de, text_line+7
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+9
ld de, text_line+8
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+10
ld de, text_line+9
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+11
ld de, text_line+10
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+12
ld de, text_line+11
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+13
ld de, text_line+12
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+14
ld de, text_line+13
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+15
ld de, text_line+14
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+16
ld de, text_line+15
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+17
ld de, text_line+16
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+18
ld de, text_line+17
ld bc, 1
call mem_CopyVRAM
ld hl, text_line+19
ld de, text_line+18
ld bc, 1
call mem_CopyVRAM
ret
display_byte ; enter with value in [de]
lcd_WaitVRAM
ld a, [de]
ld b, a
and $F0
swap a
ld [hl+], a
lcd_WaitVRAM
ld a, b
and $0F
ld [hl], a
ret
display_char
bit 7, a ;don't look up non print chars
ret nz
add a, 20 ;add imb char offset
push af
lcd_WaitVRAM
pop af
ld [hl], a
ret
initialize
di
.wait ldh a, [$44] ; LY LCDC compare
cp 144
jr nc, .wait
ld a, 0
ldh [$40], a ; LCDC lcd control
ld a, %10000000
ldh [$68], a ; BCPS
ld a, %00000000 ; palette 0 0 bg
ldh [$69], a ; BCPD
ld a,%00000000
ldh [$69],a
ld a, %11111110 ; palette 0 1
ldh [$69], a
ld a, %00011110
ldh [$69], a
ld a, %11111111 ; palette 0 2 fg test font
ldh [$69], a
ld a, %01111111
ldh [$69], a
ld a, %11111111 ; palette 0 3 fg ibm font
ldh [$69], a
ld a, %01111111
ldh [$69], a
;ld a, %00000000 ; palette 1 0 bg
;ldh [$69], a
;ld a, %00000000
;ldh [$69], a
ld hl, Font ; load my test Font
ld de, $8000
ld bc, 20*8*2
call mem_Copy
ld hl, ibm_characters ; load ibm font
ld de, $8000+20*8*2 ; $8140
ld bc, 8*128
call mem_CopyMono
ld a, 16 ; blank char
ld hl, $9800
ld bc, 20*32*32
call mem_Set
ld a, 0
ldh [$42], a ; SCY Scroll Y
ldh [$43], a ; SCX Scroll X
ld a, %00000011
ldh [$47], a ; BGP
ld a, $00000000
ldh [$FF], a ; IE
ld hl, title_text
ld de, $9800
ld bc, 20
call mem_Copy_offset
ld a, %10010001
ldh [$40], a
xor a
ld [$FF24], a
xor a
ld [counter], a
ld a, %11000000
ldh [$56], a
ld a, $FF ; send stop bit
ldh [$01], a
ld a, $83
ldh [$02], a
ld a, IEF_HILO
ldh [rIE], a
ret
wait_vb
ldh a, [$44]
cp 144
jp nz, wait_vb
ret
mem_Copy_offset::
inc b
inc c
jr .skip
.loop ld a, [hl+]
add a, 20 ; my offset hack
ld [de], a
inc de
.skip dec c
jr nz, .loop
dec b
jr nz, .loop
ret
ibm_characters
chr_IBMPC1 1,8
Font:
DW `01111100
DW `10000010
DW `10000010
DW `10000010
DW `10000010
DW `10000010
DW `01111100
DW `00000000
DW `00010000
DW `00110000
DW `00010000
DW `00010000
DW `00010000
DW `00010000
DW `00111000
DW `00000000
DW `01111100
DW `10000010
DW `00000010
DW `01111100
DW `10000000
DW `10000000
DW `11111110
DW `00000000
DW `01111100
DW `10000010
DW `00000010
DW `00011100
DW `00000010
DW `10000010
DW `01111100
DW `00000000
DW `00001100
DW `00010100
DW `00100100
DW `01000100
DW `11111110
DW `00000100
DW `00000100
DW `00000000
DW `11111110
DW `10000000
DW `10000000
DW `11111100
DW `00000010
DW `00000010
DW `11111100
DW `00000000
DW `01111100
DW `10000000
DW `10000000
DW `11111100
DW `10000010
DW `10000010
DW `01111100
DW `00000000
DW `11111110
DW `00000010
DW `00000100
DW `00001000
DW `00010000
DW `00010000
DW `00010000
DW `00000000
DW `01111100
DW `10000010
DW `10000010
DW `01111100
DW `10000010
DW `10000010
DW `01111100
DW `00000000
DW `01111100
DW `10000010
DW `10000010
DW `01111110
DW `00000010
DW `00000010
DW `01111100
DW `00000000
DW `00111000
DW `01000100
DW `10000010
DW `11111110
DW `10000010
DW `10000010
DW `10000010
DW `00000000
DW `11111100
DW `10000010
DW `10000010
DW `11111100
DW `10000010
DW `10000010
DW `11111100
DW `00000000
DW `00111100
DW `01000010
DW `10000000
DW `10000000
DW `10000000
DW `01000010
DW `00111100
DW `00000000
DW `11111000
DW `10000100
DW `10000010
DW `10000010
DW `10000010
DW `10000100
DW `11111000
DW `00000000
DW `11111110
DW `10000000
DW `10000000
DW `11111000
DW `10000000
DW `10000000
DW `11111110
DW `00000000
DW `11111110
DW `10000000
DW `10000000
DW `11111000
DW `10000000
DW `10000000
DW `10000000
DW `00000000
DW `00000000 ;16
DW `00000000
DW `00000000
DW `00000000
DW `00000000
DW `00000000
DW `00000000
DW `00000000
DW `11111111 ;17 web mark
DW `10000001
DW `00000000
DW `00000000
DW `00000000
DW `00000000
DW `00000000
DW `00000000
DW `00000000 ;18 web space
DW `00000000
DW `00000000
DW `00000000
DW `00000000
DW `10000001
DW `11111111
DW `00000000
DW `11111100 ;19
DW `10000010 ;P for parity
DW `10000010
DW `11111100
DW `10000000
DW `10000000
DW `10000000
DW `00000000
SECTION "GB_ram",BSS
counter DS 1
raw_data DS 1
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