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--- memory_map [2021/08/26 16:23] – [Interrupts] pulkomandy
+++ memory_map [2024/07/01 11:27] (current) – ↷ Links adapted because of a move operation admin
@@ Line 4: / Line 4: @@
 | 0x000000  |	0x0027FF  |	RAM     |
 | 0x002800  |	0x002FFF  |	[[PPU]]     |
-| 0x003000  |	0x0037FF  |	[[Sound]]   |
+| 0x003000  |	0x0037FF  |	[[spu]]   |
 | 0x003D00  |	0x003DFF  |	[[IO]]      |
-| 0x003e00  |	0x003E03  |	[[memory_map#General DMA|DMA]]     |
+| 0x003E00  |	0x003E03  |	[[memory_map#General DMA|DMA]]     |
 External memory starts at 0x4000. It can be mapped to the internal ROM and the two possible chips in the cartridges.
@@ Line 27: / Line 27: @@
 | 5/A/F     | IOx mask         |
-IO special functions and usage:
+Each IO port is configured by 4 registers.
-  * IOA15: act
+The direction register is 0 for input pins, 1 for output pins.
-  * IOA14-0: 15 bit RGB
-  * IOA15: SCK
-  * IOA14: SDA
-  * IOA13: SWS
-  * IOA12: CKV
-  * IOA11: FM
-  * IOA10: FP
-  * IOA9: LP
-  * IOA8: CP
-  * IOA7-0: D7-0
-  * IOC15: SPI clock
-  * IOC14: RX
-  * IOC13: TX
-  * IOC12: SPI SSB
-  * IOC11: TFT Clock
-  * IOC10: timebase 1
-  * IOC9: TAPWM
-  * IOC8: VSYNC
-  * IOC7: HSYNC
-  * IOC1: timebase 2 / external clock 1 input
-  * IOC0: TBPWM / external clock 2 input
-===== Cartridge banks selection =====
+===== Global configuration register =====
-These IO pins allow to map either the internal ROM or the two different cartridge banks into memory.
+  * Bit 0: IOA special functions select
+  * Bit 1: IOB special functions select
+These two bits allow to select one of two special functions for the IOA and IOB registers. Then each pin in that IO register can be switched between normal GPIO and special function using the MASK register.
+For IOA, special = 0 selects the TFT display interface, special = 1 selects the STN LCD interface and I2S audio output.
+For IOB, only special = 0 is documented and it selects the CSB0, CSB1, CSB2 chip select pins for external memory (further configured by port 3D23)
+  * Bit 2: IOA Wakeup enable
+  * Bit 3: IOB Wakeup enable
+  * Bit 4: IOC Wakeup enable
+These bits enable system wakeup from sleep mode from activity on the corresponding IO ports. A typical setup on the V.Smile is to enable wakeup on port B to detect when the ON button is pressed.
+===== Input pins configuration =====
+If the attribute bit for a pin is 0, the data bit can be used to set a pull up or pull down resistor on the pin.
+If the attribute bit is 1, the pin is floating without pull up or pull down.
+It is possible to read both the internal buffer and the actual state of the pin.
+===== Output pins configuration =====
+If the attribute bit for a pin is 0, the output is inverted. Writing 1 to the data bit results in a logic 0 output. If the data bit is set to 0, the result is a logic 1 output.
+If the attribute bit is 1, there is no inversion, and the data bit is output as is.
-  * IOB2: CSB3
-  * IOB1: CSB2
-  * IOB0: CSB0
 ====== Timers ======
@@ Line 77: / Line 79: @@
 | 3D1C	  | Scanline counter         |
-Timebase values:
+Timebase setup values:
+  * Bits 3-2: TMB2 frequency
-  - 00: TMB2 = 128Hz, TMB1 = 8Hz
+    * 00 - 128 Hz
-  - 01: TMB2 = 256Hz, TMB1 = 16Hz
+    * 01 - 256 Hz
-  - 10: TMB2 = 512Hz, TMB1 = 32Hz
+    * 10 - 512 Hz
-  - 11: TMB2 = 1024Hz, TMB1 = 64Hz
+    * 11 - 1024 Hz
+  * Bits 1-0: TMB1 frequency
+    * 00 - 8 Hz
+    * 01 - 16 Hz
+    * 10 - 32 Hz
+    * 11 - 64 Hz
 ===== Timer A =====
@@ Line 142: / Line 149: @@
 | 3D2D	  | Pseudo Random2	                   |
 | 3D2E	  | FIQ Sel				   |
-| 3D2F    | DS register                            |
+| 3D2F    | DS register (sets or gets data segment value of CPU status register) |
 ===== System control =====
@@ Line 178: / Line 185: @@
 The complete list of interrupt vectors is:
-^ Vector address ^ Triggered by             ^
+^ Vector address ^ Name  ^Triggered by             ^
-| FFF6           | FIQ (configured by 3D2E) |
+| FFF5           | BREAK |''break'' CPU instruction   |
-| FFF8           | PPU                      |
+| FFF6           | FIQ   |configured by 3D2E          |
-| FFF9           | SPU                      |
+| FFF7           | RESET |Console startup/reset       |
-| FFFA           | Timers A and B           |
+| FFF8           | IRQ0  |PPU                         |
-| FFFB           | UART, SPI, SIO, I2C      |
+| FFF9           | IRQ1  |SPU                         |
-| FFFC           | SPU beat and enveloppe   |
+| FFFA           | IRQ2  |Timers A and B              |
-| FFFD           | External interrupts      |
+| FFFB           | IRQ3  |UART, SPI, SIO, I2C         |
-| FFFE           | 1024, 2048 or 4096Hz ticker |
+| FFFC           | IRQ4  |SPU beat and envelope       |
-| FFFF           | 4Hz ticker, TMB1, TMB2, LVD, Key change |
+| FFFD           | IRQ5  |External interrupts         |
+| FFFE           | IRQ6  |1024, 2048 or 4096Hz ticker |
+| FFFF           | IRQ7  |4Hz ticker, Timebase 1, Timebase 2, Low voltage detect, Key change |
+As the vector addresses are only 16-bit, they can only point to the first segment (0x0000 - 0xFFFF).
 ===== External bus configuration =====
-   * Bits 11-8: Ram decode control
+   * Bits 11-8: External RAM decode control
-   * Bits 7-6: Address decode control
+     * 0xxx - No mapping
-   * Bits 5-3: Bus arbitration control
+     * 1000 - Map ''0x3ff000 - 0x3fffff'' to RAMCSB (4 kibiwords)
+     * 1001 - Map ''0x3fe000 - 0x3fffff'' to RAMCSB (8 kibiwords)
+     * 1010 - Map ''0x3fc000 - 0x3fffff'' to RAMCSB (16 kibiwords)
+     * 1011 - Map ''0x3f8000 - 0x3fffff'' to RAMCSB (32 kibiwords)
+     * 1100 - Map ''0x3f0000 - 0x3fffff'' to RAMCSB (64 kibiwords)
+     * 1101 - Map ''0x3e0000 - 0x3fffff'' to RAMCSB (128 kibiwords)
+     * 1110 - Map ''0x3c0000 - 0x3fffff'' to RAMCSB (256 kibiwords)
+     * 1111 - Map ''0x380000 - 0x3fffff'' to RAMCSB (512 kibiwords)
+   * Bits 7-6: ROM address decode control
+     * 00 - Map entire range to ROMCSB
+     * 01 - Map ''0x4000 - 0x1fffff'' to ROMCSB, ''0x200000 - 0x3fffff'' to CSB1
+     * 1x - Map ''0x4000 - 0x0fffff'' to ROMCSB, ''0x100000 - 0x1fffff'' to CSB1, ''0x200000 - 0x2fffff'' to CSB2, ''0x300000 - 0x3fffff'' to CSB3
+   * Bits 5-3: Bus arbitration priority control
+     * 101 - 1. Audio, 2. PPU, 3. CPU
+     * 111 - 1. PPU, 2. Audio, 3. CPU
    * Bits 2-1: Number of wait states
    * Bit 0: CKOEN
+External RAM mapping overrides any ROM mapping.
+On the V.Smile, both ROMCSB and CSB1 allow to access the cartridge ROM. This means bit 6 is not very useful.
+CSB2 is the cartridge RAM, and CSB3 is the system ROM. They are both enabled at the same time by using bit 7.
 ==== ADC ====
@@ Line 268: / Line 299: @@
   * 115200: FF F1
+Before using the UART, the corresponding PINs need to be configured properly. IOC13 and IOC14 must be set to "special"/"mask" mode to disable the GPIO and assign the pin to UART.
+The example below also forces CTS A (IOC8) low, allowing the first controller port to transmit data. Normally this would only be done after receiving an RTS from said controller.
+	// Enable controller CTS
+	*PORTC_DIR = 0x89c0;
+	*PORTC_ATTR = 0x89c0;
+	*PORTC_DATA = 0xf77f;
+	// Enable Uart RX (controller input)
+	*UART_BAUDRATE_LOW = 0xA0;
+	*UART_BAUDRATE_HIGH = 0xFE;
+	*UART_CONTROL = 0xc3;
+	*UART_STATUS = 3;
+	*PORTC_SPECIAL |= 0x6000; // UART Tx and Rx in "special" mode
+	*PORTC_ATTR |= 0x6000;
+	*PORTC_DIR |= 0x4000;
+Reading from the UART then is quite simple:
+  * Wait until the status register indicates Rx ready (bit 0)
+  * When Rx is ready, read the Rx data register to get the byte
+For transmitting, you need to check if the FIFO is cleared (bit 1 of status register) then you can push your bytes to the transmit register.
 ====== SPI ======