CRTC sampling and output on VGA.

CMakeLists.txt

@@ -17,6 +17,7 @@ add_compile_options(-Wall
         )
 
 add_executable(ceda2vga
+        src/crtc.c
         src/main.c
         src/draw_demo.c
         src/framebuffer.c
@@ -27,6 +28,10 @@ pico_generate_pio_header(ceda2vga
         ${CMAKE_CURRENT_LIST_DIR}/src/vga.pio
         )
 
+pico_generate_pio_header(ceda2vga
+    ${CMAKE_CURRENT_LIST_DIR}/src/crtc.pio
+)
+
 # configure stdio to make I/O on virtual usb serial port
 pico_enable_stdio_usb(ceda2vga 1)
 pico_enable_stdio_uart(ceda2vga 0)

src/crtc.c

@@ -0,0 +1,148 @@
+#include "crtc.h"
+
+#include <stdio.h>
+
+#include "hardware/pio.h"
+#include "hardware/structs/pio.h"
+#include "hardware/dma.h"
+
+#include "framebuffer.h"
+
+#include "crtc.pio.h"
+
+typedef struct PIORun
+{
+	PIO pio;     //< executing PIO
+	uint offset; //< PIO memory offset for program
+	uint sm;     //< executing SM
+} PIORun;
+
+static PIORun crtc_vsync, crtc_hsync, crtc_pixel;
+static int dma_channel;
+bool dma_ready = false;
+
+static void crtc_pixel_program_init(PIO pio, uint sm, uint offset)
+{
+	pio_sm_config config = crtc_pixel_program_get_default_config(offset);
+
+	pio_gpio_init(pio, 11);
+	sm_config_set_in_pins(&config, 11);
+	sm_config_set_in_shift(&config, true, true, 0);
+
+	pio_sm_set_consecutive_pindirs(pio, sm, 11, 1, false);
+	sm_config_set_wrap(&config, offset + crtc_pixel_wrap_target, offset + crtc_pixel_wrap);
+
+	pio_sm_init(pio, sm, offset, &config);
+
+	// not quite 4x pixel clock (2.1 = 2,25.6)
+	pio_sm_set_clkdiv_int_frac(pio, sm, 2, 26);
+
+	pio_sm_set_enabled(pio, sm, true);
+}
+
+static void crtc_hsync_program_init(PIO pio, uint sm, uint offset)
+{
+	pio_sm_config config = crtc_hsync_program_get_default_config(offset);
+
+	sm_config_set_wrap(&config, offset + crtc_hsync_wrap_target, offset + crtc_hsync_wrap);
+
+	pio_sm_init(pio, sm, offset, &config);
+	pio_sm_set_clkdiv_int_frac(pio, sm, 2, 26);
+	pio_sm_set_enabled(pio, sm, true);
+}
+
+static void crtc_vsync_program_init(PIO pio, uint sm, uint offset)
+{
+	pio_sm_config config = crtc_vsync_program_get_default_config(offset);
+
+	pio_gpio_init(pio, 15);
+	sm_config_set_wrap(&config, offset + crtc_vsync_wrap_target, offset + crtc_vsync_wrap);
+
+	pio_sm_init(pio, sm, offset, &config);
+	pio_sm_set_clkdiv_int_frac(pio, sm, 2, 26);
+	pio_sm_set_enabled(pio, sm, true);
+}
+
+int dma_counter = 0;
+static void dma_handler(void)
+{
+	dma_counter++;
+
+	// reset DMA
+	dma_channel_set_write_addr(dma_channel, &frame[2560], true);
+
+	// acknoweledge DMA
+	dma_hw->ints1 = 1 << dma_channel;
+}
+
+int crtc_frame_counter = 0;
+
+static void new_frame_handler(void)
+{
+	pio_sm_clear_fifos(crtc_pixel.pio, crtc_pixel.sm);
+
+	crtc_frame_counter++;
+
+	pio_interrupt_clear(pio1_hw, 1);
+}
+
+void crtc_machines_init(void)
+{
+	crtc_hsync.pio = crtc_vsync.pio = crtc_pixel.pio = pio1;
+
+	printf("Starting CRTC pixel machine... ");
+	if (!pio_can_add_program(crtc_pixel.pio, &crtc_pixel_program))
+		panic("cannot add program");
+	crtc_pixel.offset = pio_add_program(crtc_pixel.pio, &crtc_pixel_program);
+	crtc_pixel.sm = pio_claim_unused_sm(crtc_pixel.pio, true);
+	crtc_pixel_program_init(crtc_pixel.pio, crtc_pixel.sm, crtc_pixel.offset);
+	pio_sm_put_blocking(crtc_pixel.pio, crtc_pixel.sm, 640 - 1);
+	printf("OK\n");
+
+	printf("Starting CRTC vsync machine... ");
+	if (!pio_can_add_program(crtc_vsync.pio, &crtc_vsync_program))
+		panic("cannot add program");
+	crtc_vsync.offset = pio_add_program(crtc_vsync.pio, &crtc_vsync_program);
+	crtc_vsync.sm = pio_claim_unused_sm(crtc_vsync.pio, true);
+	crtc_vsync_program_init(crtc_vsync.pio, crtc_vsync.sm, crtc_vsync.offset);
+	printf("OK\n");
+
+	printf("Starting CRTC hsync machine... ");
+	if (!pio_can_add_program(crtc_hsync.pio, &crtc_hsync_program))
+		panic("cannot add program");
+	crtc_hsync.offset = pio_add_program(crtc_hsync.pio, &crtc_hsync_program);
+	crtc_hsync.sm = pio_claim_unused_sm(crtc_hsync.pio, true);
+	crtc_hsync_program_init(crtc_hsync.pio, crtc_hsync.sm, crtc_hsync.offset);
+	pio_sm_put_blocking(crtc_hsync.pio, crtc_hsync.sm, 128 - 1);
+	printf("OK\n");
+
+	printf("Setting up new frame interrupt... ");
+	// Frame interrupt is asserted on PIO1 interrupt 1 by SM1
+	pio_set_irq1_source_enabled(crtc_vsync.pio, pis_interrupt1,
+	                            true); // allow SM1 of PIO to fire the interrupt
+	irq_set_exclusive_handler(PIO1_IRQ_1, new_frame_handler); // set handler for IRQ1 of PIO
+	irq_set_enabled(PIO1_IRQ_1, true);                        // enable interrupt
+	printf("OK\n");
+
+	printf("Setting up CRTC DMA... ");
+	dma_channel = dma_claim_unused_channel(true);
+	printf("channel %d... ", dma_channel);
+	dma_channel_config dma_config = dma_channel_get_default_config(dma_channel);
+	channel_config_set_transfer_data_size(&dma_config, DMA_SIZE_32);
+	channel_config_set_read_increment(&dma_config, false);
+	channel_config_set_write_increment(&dma_config, true);
+
+	channel_config_set_dreq(&dma_config, DREQ_PIO1_RX0);
+
+	// setup transfer acknowledge interrupt
+	dma_channel_set_irq1_enabled(dma_channel, true);
+
+	irq_set_exclusive_handler(DMA_IRQ_1, dma_handler);
+	irq_set_enabled(DMA_IRQ_1, true);
+
+	dma_channel_configure(dma_channel, &dma_config, &frame[2560], &pio1_hw->rxf[0], 640 * 128 / 32,
+	                      true);
+
+	dma_ready = true;
+	printf("OK\n");
+}

src/crtc.h

@@ -0,0 +1,6 @@
+#ifndef CRTC_H
+#define CRTC_H
+
+void crtc_machines_init(void);
+
+#endif

src/crtc.pio

@@ -0,0 +1,37 @@
+.program crtc_pixel
+
+entrypoint_crtc_pixel:
+    pull
+
+.wrap_target
+    mov y, osr
+    wait irq 6
+visible_line_loop:
+    in pins, 1 [2]
+    jmp y-- visible_line_loop
+.wrap
+
+.program crtc_hsync
+    pull
+
+.wrap_target
+    mov y, osr
+    wait irq 1
+scanlines_loop:
+    set x, 7
+    wait 1 gpio 14
+    wait 0 gpio 14
+back_porch_loop:
+    jmp x-- back_porch_loop [31]
+    irq set 6
+    jmp y-- scanlines_loop
+.wrap
+
+
+.program crtc_vsync
+entrypoint_ceda_crt_vsync:
+.wrap_target
+    wait 0 gpio 15
+    wait 1 gpio 15
+    irq set 1
+.wrap

src/main.c

@@ -17,15 +17,42 @@
 #include "draw_demo.h"
 #include "framebuffer.h"
 #include "vga.h"
+#include "crtc.h"
+
+extern int crtc_frame_counter;
+extern int dma_counter;
 
 int main()
 {
 	stdio_init_all();
+	sleep_ms(5000);
 
-	draw_demo();
+	// draw_demo();
+	// horizontal lines
+	draw_line(0, 0, 640 - 1, 0, true);
+	draw_line(0, 240 - 1, 640 - 1, 240 - 1, true);
+	draw_line(0, 480 - 1, 640 - 1, 480 - 1, true);
+
+	// vertical lines
+	draw_line(0, 0, 0, 480 - 1, true);
+	draw_line(320 - 1, 0, 320 - 1, 480 - 1, true);
+	draw_line(638, 0, 638, 480 - 1, true); // last pixel of a line can't be set, see set_pixel()
 
 	vga_machines_init();
 
+	sleep_ms(10);
+
+	crtc_machines_init();
+
+	printf("All ready: OK\n");
+
+	for (;;)
+	{
+		printf("CRTC frames: %d\n", crtc_frame_counter);
+		printf("DMA counter: %d\n", dma_counter);
+		sleep_ms(1000);
+	}
+
 	for (;;)
 	{
 		// moving sine

src/vga.c

@@ -237,7 +237,7 @@ void vga_machines_init(void)
 	pio_sm_put_blocking(vga_pixel.pio, vga_pixel.sm, 640 - 1);
 	printf("OK\n");
 
-	printf("Setting up DMA... ");
+	printf("Setting up VGA DMA... ");
 	dma_channel = dma_claim_unused_channel(true);
 	dma_channel_config dma_config = dma_channel_get_default_config(dma_channel);
 	channel_config_set_transfer_data_size(&dma_config, DMA_SIZE_32);
@@ -260,8 +260,6 @@ void vga_machines_init(void)
 
 	dma_ready = true;
 	printf("OK\n");
-
-	printf("Now running.\n");
 }
 
 /**