SummerCart64 Firmware

A FPGA firmware written in Verilog for SummerCart64.

Technical Reference Manual

Bus peripheral addresses

0x1000 0000 - 0x13FF FFFF - [R/W] SDRAM Memory
0x1D00 0000 - 0x1D00 07FF - [R/W] EEPROM Memory
0x1E00 0000 - 0x1E00 0007 - [R/W] Cart Registers

Memory spaces

SDRAM Memory

Base address: 0x1000 0000
Length: 64 MB
Access: Read or Write, 2 byte (16 bit) aligned

64 MB of SDRAM memory. Available on the bus when SDRAM bit in CART->CR register is set. Used as ROM storage.

EEPROM Memory

Base address: 0x1D00 0000
Length: 2 kB
Access: Read or Write, 4 byte (32 bit) aligned

2 kB of EEPROM Memory. Available on the bus when EEPROM_PI bit in CART->CR register is set. Used to upload/download EEPROM contents to/from PC.

Registers

Cart (CART) registers

Base address: 0x1E00 0000

Configuration register (CR)

Address offset: 0x00
Powerup value: 0b0000 0000
Soft reset value: 0b00xx x000
Access: Read or write, 4 byte (32 bit) aligned

This register is used to enable or disable various modules available on the cart.

31:5	4	3	2	1	0
0	EEPROM_16K	EEPROM_EN	0	SDRAM_EN	0
x	R/W	R/W	x	R/W	x

Bits 31:5: Reserved. Reads as 0, writes are ignored but it's recommended to be set as 0 for future compatibility.
Bit 4 EEPROM_16K: Sets ID returned by EEPROM to identify itself as 4k or 16k variant.
- 0: EEPROM 4k variant
- 1: EEPROM 16k variant
Bit 3 EEPROM_EN: Enable EEPROM access through SI bus.
- 0: EEPROM SI access disabled
- 1: EEPROM SI access enabled
Bit 2: Reserved. Reads as 0, writes are ignored but it's recommended to be set as 0 for future compatibility.
Bit 1 SDRAM_EN: Enable SDRAM access at address base 0x1000 0000. When disabled bootloader flash image is mapped at this address. Cleared by hardware on N64 Reset/NMI event.
- 0: SDRAM disabled
- 1: SDRAM enabled
Bit 0: Reserved. Reads as 0, writes are ignored but it's recommended to be set as 0 for future compatibility.
- 0: Flash disabled
- 1: Flash enabled

CIC and TV type override register (CIC_TV)

Address offset: 0x04
Powerup value: 0x0000 0000
Access: Read or write, 4 byte (32 bit) aligned

This register is used for PC -> bootloader communication.

31:6	5:4	3:0
SWITCH	TV_TYPE	CIC_TYPE
R/W	R/W	R/W

Bits 31:6 SWITCH: Additional bits that can be passed to bootloader, currently unused.
Bits 5:4 TV_TYPE: Overrides TV type in bootloader. Used only when CIC_TYPE value is valid (values 1 - 7).
- 0: PAL TV type
- 1: NTSC TV type
- 2: MPAL TV type
- 3: No TV type override - use TV type provided by ROM header
Bits 3:0 CIC_TYPE: Overrides CIC type in bootloader.
- 0: No CIC type override - use CIC type determined from ROM bootcode
- 1: CIC 5101
- 2: CIC 6101/7102
- 3: CIC 6102/7101
- 4: CIC X103
- 5: CIC X105
- 6: CIC X106
- 7: CIC 8303
- 8 - 15: Same effect as value 0

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