Code refractoring, bugfixing and new features:

- update .gitignore
- update psxPSI code
- changed simulation to state maching based (following darren approach)
- add missing NULL checks in memory_card.c
- changed allocation of memory card in RAM memory
- add global config.h file
- led now reflects sync status (ram and flash memory card)
- change auto sync delay to 5 seconds
- change MSC ram disk export to automatic (no need for safe removal)

Compilation requires fix for pico-sdk not yet merged:
raspberrypi/pico-sdk#936

.gitignore

@@ -5,4 +5,11 @@ build/
 .vscode/.cortex*
 
 # FatFS documentation
-ff14b/documents
+ff14b/documents
+
+# VSCode
+.vscode/settings.json
+
+# Clion
+/.idea
+/cmake-build-debug 

CMakeLists.txt

@@ -15,6 +15,7 @@ pico_generate_pio_header(PicoMemcard ${CMAKE_CURRENT_LIST_DIR}/psxSPI.pio)
 
 # Example source
 target_sources(PicoMemcard PUBLIC
+    ${CMAKE_SOURCE_DIR}/src/led.c
     ${CMAKE_SOURCE_DIR}/src/lfs_disk.c
     ${CMAKE_SOURCE_DIR}/src/lfs_flash_handler.c
     ${CMAKE_SOURCE_DIR}/src/main.c
@@ -38,6 +39,6 @@ target_include_directories(PicoMemcard PUBLIC
 
 pico_enable_stdio_uart(PicoMemcard 1)	# enable only UART stdio
 
-target_link_libraries(PicoMemcard pico_stdlib pico_time hardware_flash hardware_pio tinyusb_device tinyusb_board)
+target_link_libraries(PicoMemcard pico_stdlib pico_multicore pico_time hardware_flash hardware_pio tinyusb_device tinyusb_board)
 
 pico_add_extra_outputs(PicoMemcard)

inc/config.h

@@ -0,0 +1,32 @@
+#ifndef __CONFIG_H__
+#define __CONFIG_H__
+
+/* Global configuration options for PicoMemcard */
+#define TUD_MOUNT_TIMEOUT	3000			// max time (in ms) before giving up on MSC mode (USB) and starting memcard simulation
+#define MSC_WRITE_SYNC_TIMEOUT 1 * 1000		// time (in ms) expired since last MSC write before exporting RAM disk into LFS
+#define IDLE_AUTOSYNC_TIMEOUT 5 * 1000		// time (in ms) the memory card must be inactive before automatic sync from RAM to LFS
+#define MEMCARD_FILE_NAME	"memcard.mcr"	// name of memory card file image
+
+/* Board targeted by build */
+#define TARGET_PICO
+//#define TARGET_RP2040ZERO
+
+
+/* PSX Interface Pinout */
+#ifdef TARGET_PICO
+	#define PIN_DAT 5
+	#define PIN_CMD PIN_DAT + 1		// must be immediately after PIN_DAT
+	#define PIN_SEL PIN_CMD + 1		// must be immediately after PIN_CMD
+	#define PIN_CLK PIN_SEL + 1		// must be immediately after PIN_SEL
+	#define PIN_ACK 9
+#endif
+
+#ifdef TARGET_RP2040ZERO
+	#define PIN_DAT 9
+	#define PIN_CMD PIN_DAT + 1		// must be immediately after PIN_DAT
+	#define PIN_SEL PIN_CMD + 1		// must be immediately after PIN_CMD
+	#define PIN_CLK PIN_SEL + 1		// must be immediately after PIN_SEL
+	#define PIN_ACK 13
+#endif
+
+#endif

inc/led.h

@@ -0,0 +1,12 @@
+#ifndef __LED_H__
+#define __LED_H__
+
+#include "pico/stdlib.h"
+
+void led_output_sync_status(bool out_of_sync);
+void blink(int amount, int on_ms, int off_ms);
+void blink_fast(int amount);
+void blink_normal(int amount);
+void blink_slow(int amount);
+
+#endif

inc/lfs_disk.h

@@ -8,9 +8,6 @@
 #define LFS_BLOCK_COUNT 70
 #define LFS_BLOCK_SIZE 4096
 
-#define MEMCARD_FILE_NAME "memcard.mcr"     // name of memcard file inside system
-#define MEMCARD_FILE_CONTENT_SIZE 131072	// size of memcard file content in bytes (128KB)
-
 /* LittleFS filesystem configuration */
 extern const struct lfs_config LFS_CFG;
 

inc/memory_card.h

@@ -4,10 +4,10 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-#define MC_SEC_SIZE 128			// size of single sector in bytes
-#define MC_SIZE MC_SEC_SIZE * 1024		// size of memory card in bytes
-#define MC_MAX_SEC 0x3ff
-#define MC_FLAG_BYTE_DEF 0x08	// bit 3 set = new memory card inserted
+#define MC_SEC_SIZE			128		// size of single sector in bytes
+#define MC_SEC_COUNT		1024	// number of sector in one memory card
+#define MC_SIZE				MC_SEC_SIZE * MC_SEC_COUNT		// size of memory card in bytes
+#define MC_FLAG_BYTE_DEF	0x08	// bit 3 set = new memory card inserted
 
 #define MC_ID1 0x5A
 #define MC_ID2 0x5D
@@ -19,20 +19,31 @@
 #define MC_BAD_SEC 0xFF
 #define MC_BAD_CHK 0x4E
 
+/* Error codes */
+#define MC_OK				0
+#define MC_MOUNT_ERR		1
+#define MC_FILE_OPEN_ERR	2
+#define MC_FILE_READ_ERR	3
+#define MC_FILE_WRITE_ERR	4
+#define MC_FILE_SIZE_ERR	5
+#define MC_NO_INIT			6
+
 typedef struct {
 	uint8_t flag_byte;
-	uint8_t data[MC_SIZE];
+	uint8_t* data;
 	bool out_of_sync;
 	uint32_t last_operation_timestamp;
-} MemoryCard;
-
-uint32_t memory_card_init(MemoryCard* mc);
-bool memory_card_is_sector_valid(MemoryCard* mc, uint32_t sector);
-uint8_t* memory_card_get_sector_ptr(MemoryCard* mc, uint32_t sector);
-void memory_card_set_sync(MemoryCard* mc, bool out_of_sync);
-bool memory_card_get_sync(MemoryCard* mc);
-void memory_card_update_timestamp(MemoryCard* mc);
-uint32_t memory_card_sync(MemoryCard* mc);
-uint32_t memory_card_reset_seen_flag(MemoryCard* mc);
+} memory_card_t;
+
+uint32_t memory_card_init(memory_card_t* mc);
+uint32_t memory_card_import(memory_card_t* mc, uint8_t* file_name);
+bool memory_card_is_sector_valid(memory_card_t* mc, uint32_t sector);
+uint8_t* memory_card_get_sector_ptr(memory_card_t* mc, uint32_t sector);
+void memory_card_set_sync(memory_card_t* mc, bool out_of_sync);
+bool memory_card_get_sync(memory_card_t* mc);
+void memory_card_update_timestamp(memory_card_t* mc);
+bool memory_card_sync_required(memory_card_t* mc);
+uint32_t memory_card_sync(memory_card_t* mc);
+void memory_card_reset_seen_flag(memory_card_t* mc);
 
 #endif

psxSPI.pio

@@ -26,11 +26,15 @@ irq set 0		; signal CPU that SEL went high
 ;	waits for sel_monitor signal before starting execution
 sel_high:
 irq wait 4		; wait for SEL monitor to signal SM start
+set x, 7		; set the bit counter
 .wrap_target
+recv:
 wait 0 pin 2	; wait for clock to fall
 wait 1 pin 2	; wait for rising clock edge
-in pins 1		; sample 1 bit form CMD line
-irq clear 1		; signal ACK timer to start
+in pins 1		; sample 1 bit from CMD line
+jmp x-- recv	; receive and count 8 bits
+set x, 7		; reset bit counter - we now have a full byte
+irq clear 5		; trigger ack
 .wrap
 
 .program dat_reader
@@ -77,19 +81,17 @@ out pindirs 1	; output 1 bit (by changing pin direction)
 ; Set pins mapping:
 ;	0 - ACK
 ; Program description:
-;	Sets ACK line low, waits for irq 1 to be lowered by cmd_reader.
-;	Timing is based on the first bit read by cmd_reader.
-.wrap_target
-irq wait 1		[31]	; 32 cycles delay (1 for instruction)
-nop	[23]				; 24 cycles delay (1 for instruction), total of 56 cycles
-set pindirs, 1	[2]		; keep ack low for more than half PSX clock
+;	Sets ACK line low roughly 12uS after 8 clocks have been counted.
 set pindirs, 0
+.wrap_target
+irq wait 5 [30]		; Wait for a byte to be received and delay for 12uS
+set pindirs, 1 [5]	; keep ack low for more than half PSX clock
+set pindirs, 0		; Set ACK pin to Hi-Z
 .wrap
 
 
 % c-sdk {
-#define ACK_CLKDIV 86	// with pico default clock (125 Mhz) results in a frequency around 6 time greater than PSX SPI frequency
-#define ACK_IRQ 1
+#define SLOW_CLKDIV 50	// 125MHz divided down to 2.5 MHz - we need this so we don't count clocks not meant for us on systems like the PS2
 
 static inline void sel_monitor_program_init(PIO pio, uint sm, uint offset, uint pin_sel) {
 	pio_sm_config c = sel_monitor_program_get_default_config(offset);
@@ -99,6 +101,8 @@ static inline void sel_monitor_program_init(PIO pio, uint sm, uint offset, uint
 	pio_gpio_init(pio, pin_sel);		// SEL pin
 	/* Interrupt Configuration */
 	pio_set_irq0_source_enabled(pio, pis_interrupt0, true);
+	/* Clock configuration */
+	sm_config_set_clkdiv_int_frac(&c, SLOW_CLKDIV, 0x00);
 	/* Initialize SM */
 	pio_sm_init(pio, sm, offset, &c);
 }
@@ -114,6 +118,8 @@ static inline void cmd_reader_program_init(PIO pio, uint sm, uint offset, uint p
 	/* Fifo Configuration */
 	sm_config_set_in_shift(&c, true, true, 8);		// shift ISR to right, autopush every 8 bits
 	sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_RX);	// join RX FIFO
+	/* Clock configuration */
+	sm_config_set_clkdiv_int_frac(&c, SLOW_CLKDIV, 0x00);
 	/* Initialize SM */
 	pio_sm_init(pio, sm, offset, &c);
 }
@@ -152,6 +158,8 @@ static inline void dat_writer_program_init(PIO pio, uint sm, uint offset, uint p
 	/* FIFO Configuration */
 	sm_config_set_out_shift(&c, true, true, 8);		// shift OSR to right, autopull every 8 bits
 	sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);	// join TX FIFO
+	/* Clock configuration */
+	sm_config_set_clkdiv_int_frac(&c, SLOW_CLKDIV, 0x00);
 	/* Initialize SM */
 	pio_sm_init(pio, sm, offset, &c);
 }
@@ -171,7 +179,7 @@ static inline void ack_sender_program_init(PIO pio, uint sm, uint offset, uint p
 	pio_sm_set_consecutive_pindirs(pio, sm, pin_ack, 1, false);		// set ACK pin as input (initial configuration)
 	pio_gpio_init(pio, pin_ack);									// init ACK pin
 	/* Clock Configuration */
-	sm_config_set_clkdiv_int_frac(&c, ACK_CLKDIV, 0x00);
+	sm_config_set_clkdiv_int_frac(&c, SLOW_CLKDIV, 0x00);
 	/* Initialize SM */
 	pio_sm_init(pio, sm, offset, &c);
 }

src/led.c

@@ -0,0 +1,40 @@
+#include "led.h"
+#include "hardware/gpio.h"
+
+#define LED_PIN 25
+
+void led_output_sync_status(bool out_of_sync) {
+	gpio_put(LED_PIN, !out_of_sync);
+}
+
+void blink(int amount, int on_ms, int off_ms) {
+	bool initial_state = gpio_get(LED_PIN);
+	if(initial_state) {
+		/* turn led off if already on */
+		gpio_put(LED_PIN, false);
+		sleep_ms(off_ms);
+		--amount;	// last blink is performed while restoring led state
+	}
+	for(int i = 0; i < amount; ++i) {
+		gpio_put(LED_PIN, true);
+		sleep_ms(on_ms);
+		gpio_put(LED_PIN, false);
+		sleep_ms(off_ms);
+	}
+	if(initial_state) {
+		/* restore led state */
+		gpio_put(LED_PIN, true);
+	}
+}
+
+void blink_fast(int amount) {
+	blink(amount, 250, 250);
+}
+
+void blink_normal(int amount) {
+	blink(amount, 500, 500);
+}
+
+void blink_slow(int amount) {
+	blink(amount, 1000, 1000);
+}

src/main.c

@@ -15,8 +15,9 @@
 #include "lfs_disk.h"
 /* Memcard Simulation */
 #include "memcard_simulator.h"
+/* Global Configuration */
+#include "config.h"
 
-#define TUD_MOUNT_TIMEOUT	3000	// max time (in ms) before giving up on MSC mode and starting memcard simulation
 bool tud_mount_status = false;
 
 void cdc_task(void);