XCLK is now generated (in theory)

GPIO gets inited
PIO gets setup (no DMA currently)

src/PicoIris.cpp

@@ -9,8 +9,11 @@
 #include "hardware/clocks.h"
 #include "hardware/uart.h"
 
+#include <ov2640/SCCB.hpp>
 #include <ov2640/camera.hpp>
 
+// PIO2 is reserved for the cam data retreive functions
+
 camera_config_t left_eye_config = {
     .pin_pwdn = -1,                   /*!< GPIO pin for camera power down line */ //? Also called PWDN, or set to -1 and tie to GND
     .pin_reset = -1,                  /*!< GPIO pin for camera reset line */ //? Cam reset, or set to -1 and tie to 3.3V

src/ov2640/SCCB.cpp

@@ -1,7 +1,9 @@
-#include <sccb.hpp>
+#include <SCCB.hpp>
+#include <camera.hpp>
 #include "hardware/i2c.h"
 #include "pico/stdlib.h"
 #include "src/pio/i2c/pio_i2c.h"
+
 SCCB::SCCB(uint8_t sda_pin, uint8_t scl_pin) {
     this->sda = sda_pin;
     this->scl = scl_pin;

src/ov2640/SCCB.hpp

@@ -1,4 +1,7 @@
-#include <camera.hpp>
+typedef struct {
+    uint8_t reg;   ///< Register address
+    uint8_t value; ///< Value to store
+} register_val_t;
 
 class SCCB {
 public:

src/ov2640/camera.cpp

@@ -1,7 +1,34 @@
 #include <camera.hpp>
-#include <sccb.hpp>
+#include <SCCB.hpp>
 #include "pico/stdlib.h"
 
+#include "../../hardware_dma/include/hardware/dma.h"
+#include "hardware/pwm.h"
+#include "hardware/gpio.h"
+#include "hardware/irq.h"
+#include "hardware/pio.h"
+
+// TODO: Stolen from Adafruit repo (Check if correct)
+
+// PIO code in this table is modified at runtime so that PCLK is
+// configurable (rather than fixed GP## or PIN offset). Data pins
+// must be contiguous but are otherwise configurable.
+static uint16_t capture_pio_opcodes[] = {
+    // Only monitor PCLK when HSYNC is high. This is more noise-immune
+    // than letting it fly.
+    0b0010000010000000, // WAIT 1 GPIO 0 (mask in HSYNC pin before use)
+    0b0010000010000000, // WAIT 1 GPIO 0 (mask in PCLK pin before use)
+    0b0100000000001000, // IN PINS 8 -- 8 bits into RX FIFO
+    0b0010000000000000, // WAIT 0 GPIO 0 (mask in PCLK pin before use)
+};
+
+
+static struct pio_program cap_pio_program = {
+    .instructions = capture_pio_opcodes,
+    .length = sizeof capture_pio_opcodes / sizeof capture_pio_opcodes[0],
+    .origin = -1,
+};
+
 register_val_t OV2640_init[] = {
     // Ideas from rp2040_ov2640-main repo
     // OV2640 camera initialization after reset
@@ -300,7 +327,16 @@ OV2640::OV2640(camera_config_t config) {
 
 int OV2640::begin() {
     // Initialize peripherals for parallel+I2C camera:
-    //! TODO: start XCLK before SCCB init
+    
+    // XCLK generation (~20.83 MHz)
+	gpio_set_function(this->config.pin_xclk, GPIO_FUNC_PWM);
+	uint slice_num = pwm_gpio_to_slice_num(this->config.pin_xclk);
+	// 6 cycles (0 to 5), 125 MHz / 6 = ~20.83 MHz wrap rate
+	pwm_set_wrap(slice_num, 5);
+	pwm_set_gpio_level(this->config.pin_xclk, 3);
+	pwm_set_enabled(slice_num, true);
+
+    // Init SCCB
     this->sccb = SCCB(this->config.pin_sccb_sda,this->config.pin_sccb_scl);
     this->sccb.begin(this->config.sccb_ctrl);
   
@@ -316,8 +352,96 @@ int OV2640::begin() {
   
     // Init main camera settings
     this->sccb.writeList(OV2640_init, sizeof OV2640_init / sizeof OV2640_init[0]);
-  
+
+    gpio_init(this->config.pin_pclk);
+    gpio_set_dir(this->config.pin_pclk, GPIO_IN);
+    gpio_init(this->config.pin_vsync);
+    gpio_set_dir(this->config.pin_vsync, GPIO_IN);
+    gpio_init(this->config.pin_href);
+    gpio_set_dir(this->config.pin_href, GPIO_IN);
+    for (uint8_t i = 0; i < 8; i++) {
+      gpio_init(this->config.pin_data_base + i);
+      gpio_set_dir(this->config.pin_data_base + i, GPIO_IN);
+    }
+
+    // PIO periph to use is currently specified by the user in the arch struct,
+    // but I suppose this could be written to use whatever PIO has resources.
+
+    // Mask the GPIO pin used PCLK into the PIO opcodes -- see notes at top
+    // TODO: check if this is correct (code made for rp2040 not rp2350 so it might differ)
+    capture_pio_opcodes[0] |= (this->config.pin_href & 31);
+    capture_pio_opcodes[1] |= (this->config.pin_pclk & 31);
+    capture_pio_opcodes[3] |= (this->config.pin_pclk & 31);
+
+    uint offset = pio_add_program(pio2, &cap_pio_program);
+    this->sm = pio_claim_unused_sm(pio2, true); // 0-3
+
+    // host->pins->data[0] is data bit 0. PIO code requires all 8 data be
+    // contiguous.
+    pio_sm_set_consecutive_pindirs(pio2, this->sm, this->config.pin_data_base, 8, false);
+
+    pio_sm_config c = pio_get_default_sm_config();
+    c.pinctrl = 0; // SDK fails to set this
+    sm_config_set_wrap(&c, offset, offset + cap_pio_program.length - 1);
+
+    sm_config_set_in_pins(&c, this->config.pin_data_base);
+    sm_config_set_in_shift(&c, false, true, 16); // 1 pixel (16b) ISR to FIFO
+    sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_RX);
+
+    pio_sm_init(pio2, this->sm, offset, &c);
+    pio_sm_set_enabled(pio2, this->sm, true);
+
+    // SET UP DMA ------------------------------------------------------------
+
+    this->dma_channel = dma_claim_unused_channel(false); // don't panic
+
+    this->dma_config = dma_channel_get_default_config(this->dma_channel);
+    channel_config_set_transfer_data_size(&this->dma_config, DMA_SIZE_16);
+    channel_config_set_read_increment(&this->dma_config, false);
+    channel_config_set_write_increment(&this->dma_config, true);
+    channel_config_set_bswap(&this->dma_config, true); // TODO: bswap should be true or false? 
+    
+    // Set PIO RX as DMA trigger. Input shift register saturates at 16 bits
+    // (1 pixel), configured in data size above and in PIO setup elsewhere.
+    channel_config_set_dreq(&this->dma_config,
+                            pio_get_dreq(pio2, this->sm, false));
+    // Set up baseline DMA configuration...it's initially lacking destination
+    // and count, set later (dma_change()) after resolution is known. DMA
+    // isn't started until later, and is triggered in the vsync interrupt.
+    dma_channel_configure(this->dma_channel, &this->dma_config, NULL,
+                            &pio2->rxf[this->sm], 0, false);
+
+    // Set up end-of-DMA interrupt
+    dma_channel_set_irq0_enabled(this->dma_channel, true);
+    // TODO: setup diffrent handlers for each cam???
+    irq_set_exclusive_handler(DMA_IRQ_0, iCap_dma_finish_irq);
+    irq_set_enabled(DMA_IRQ_0, true);
+
+    // SET UP VSYNC INTERRUPT ------------------------------------------------
+
+    gpio_set_irq_enabled_with_callback(this->config.pin_vsync, GPIO_IRQ_EDGE_RISE, true,
+                                        &iCap_vsync_irq);
+
     return 0;
 }
 
+// TODO: figure out how to get from where does IRQs originate from
+// TODO: how to transfer data?
+// TODO: what?
+// TODO: eep time
+// TODO: make a static array with something like a hashmap containing GPIO -> sm+dma_channel mappings
+// Pin interrupt on VSYNC calls this to start DMA transfer (unless suspended).
+static void iCap_vsync_irq(uint gpio, uint32_t events) {
+    pio_sm_clear_fifos(pio2, archptr->sm);
+    dma_channel_start(archptr->dma_channel);
+  }
+  
+// TODO: make a static array with something like a hashmap containing GPIO -> sm+dma_channel mappings
+  static void iCap_dma_finish_irq() {
+    // Channel MUST be reconfigured each time (to reset the dest address).
+    dma_channel_set_write_addr(archptr->dma_channel,
+                               (uint8_t *)(capptr->getBuffer()), false);
+    dma_hw->ints0 = 1u << archptr->dma_channel; // Clear IRQ
+  }
+
 // TODO: add all of the specific controls like brightness and all of that scheiße

src/ov2640/camera.hpp

@@ -1,4 +1,3 @@
-
 // TODO: Add XCLK settings
 typedef struct {
     int pin_pwdn;                   /*!< GPIO pin for camera power down line */ //? Also called PWDN, or set to -1 and tie to GND
@@ -14,11 +13,6 @@ typedef struct {
     uint8_t sccb_ctrl;              /* Select i2c controller ctrl: 0 - i2c0, 1 - i2c1, 2 - pio0, 3 - pio1, 4 - pio2 */
 } camera_config_t;
 
-typedef struct {
-    uint8_t reg;   ///< Register address
-    uint8_t value; ///< Value to store
-} register_val_t;
-
 class OV2640 {
 public:
     OV2640(camera_config_t config);
@@ -28,6 +22,9 @@ public:
 private:
     camera_config_t config;
     SCCB sccb;
+    uint sm;
+    uint dma_channel;
+    dma_channel_config dma_config;
 };
 
 //? Refer to https://github.com/adafruit/Adafruit_ImageCapture/blob/main/src/Adafruit_iCap_OV2640.h to check whatever this shit below even is??