WIP reimplementing video generation with shift register

pat80-io-devices/composite-pal-adapter/software/avr-assembly/Makefile

@@ -2,4 +2,8 @@ pal-adapter:
 	@echo "Building pal adapter rom..."
 	@avra main.asm
 	@echo "Writing to ATMEGA1284..."
-	@minipro -w main.hex -p ATMEGA1284
+	@minipro -w main.hex -p ATMEGA1284
+
+fuses:
+	@echo "Writing fuses.conf..."
+	@minipro -w fuses.conf -c config -p ATMEGA1284

pat80-io-devices/composite-pal-adapter/software/avr-assembly/README.md

@@ -1,4 +1,12 @@
 # Atmega Microcontroller
+
+## Auto build & flash
+Use make to build & flash automatically.
+The first time the microcontroller is flashed, is needed to flash fuses:
+`make fuses`
+Then, every time the asm code is changed, it can be built and flashed with:
+`make`
+
 ## Build ASM code
 `avra filename.asm` (generates *filename.hex*)
 

pat80-io-devices/composite-pal-adapter/software/avr-assembly/fuses.conf

@@ -1,4 +1,4 @@
-fuses_lo = 0xAF
+fuses_lo = 0xEF
 fuses_hi = 0x99
 fuses_ext = 0xff
 lock_byte = 0xff

pat80-io-devices/composite-pal-adapter/software/avr-assembly/main.asm

@@ -4,7 +4,7 @@
 ; This also displays byte's MSB pixel "for free", as the video pin is PD7 (last bit of PORTA).
 ;
 ; INTERFACING WITH PAT80:
-; Use PortB as data port. Before writing anything, issue a read (pin RW HIGH) and check the busy pin on the data port. 
+; Use PortB as data port. Before writing anything, issue a read (pin RW HIGH) and check the busy pin on the data port.
 ; If the busy pin is high, retry reading until goes low. When the busy pin goes low, we have... TODO
 ;
 ; ELECTRONICALLY:
@@ -45,17 +45,18 @@
 .def HIGH_ACCUM = r16 ; an accumulator in high registers to be used outside of interrupts
 
 ; define constant
-.equ VIDEO_PORT_OUT = PORTA		; Used all PORTA, but connected only PA0
+.equ VIDEO_PORT_OUT = PORTA		; PORTA is connected to a parallel-in serial-out shift register
 .equ SYNC_PIN = PC0			; Sync pin (pin 22)
 .equ DEBUG_PIN = PC1		; DEBUG: Single vertical sync pulse to trigger oscilloscope (pin 23)
-.equ DATA_PORT_IN = PINB
-.equ CLK_PIN = PD0
-.equ RS_PIN = PD1
-.equ BUSY_PIN = PD2
+.equ SR_LD_PIN = PC2		; LD pin of shift register (active low)
+.equ DATA_PORT_IN = PIND
+.equ CLK_PIN = PC3
+.equ RS_PIN = PC4
+.equ BUSY_PIN = PC5
 
 ; memory
 .equ FRAMEBUFFER = 0x0100
-.equ FRAMEBUFFER_END = 0x3EC0
+.equ FRAMEBUFFER_END = 0x3D00	; 15kb @ 512x240
 
 ; start vector
 .org 0x0000