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https://github.com/pdaxrom/N64cart

RP2040 N64 cartridge
https://github.com/pdaxrom/N64cart

cartridge firmware homebrew nintendo-64 raspberry-pi-pico rp2040 uart usb

Last synced: 3 months ago
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RP2040 N64 cartridge

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README 

        
# N64cart - N64 flash cartridge



* [Intro](#intro)

* [Concept](#concept)

  * [Project files](#project-files)

  * [Features](#features)

  * [Memory mapping](#memory-mapping)

* [PCB](#pcb)

  * [Order notes](#order-notes)

  * [Assembly notes](#assembly-notes)

* [Build firmware](#build-firmware)

* [Cartrigde utility](#cartrigde-utility)

  * [Build](#build)

  * [How to use](#how-to-use)

* [Total cartridge cost (32MB version)](#total-cartridge-cost-32mb-version)

* [Photos version 2](#photos-version-2)

* [BOM list for version 3](#bom-list-for-version-3)

* [Photos version 3](#photos-version-3)



## Intro



Existing N64 flash cartridges are quite expensive, but thanks to Konrad Beckmann, who first used a raspberry pi pico as a memory controller, he managed to create a cheap version that can be built at home.



Hardware and firmware initially are forked from Konrad Beckmann [PicoCart64](https://github.com/kbeckmann/PicoCart64)



N64 cartridge connector footprint for Eagle CAD from [SummerCart64](https://github.com/Polprzewodnikowy/SummerCollection)



N64 ROM boot code derived from [N64FlashcartMenu](https://github.com/Polprzewodnikowy/N64FlashcartMenu) and [N64 DreamOS ROM](https://github.com/khill25/Dreamdrive64/tree/main/sw/n64)



## Concept



The main idea is to make the cartridge as simple and cheap as possible. Contrary to Konrad's idea of multiplexed PSRAM chips and two RP2040, I decided to use one SPI flash memory chip and one RP2040. Modern flash chips allow to erase and flash data more than 100,000 times, which is more than enough for home use for many years. Since the RP2040 does not support SPI flash chips larger than 16MB, it was decided to use page mode with page switching through the Extended Address register (EA register). Unfortunately, this method has a problem with long switching of 16MB pages, because need to disable the XIP mode, enable the SPI mode to change the page and enable the XIP back. Therefore, it was decided to use QSPI with 32-bit addressing mode without XIP.

To effectively work with cartridge flash chip, a special version of the filesystem was created - romfs, which allows to map sectors of saved files as a continuous data area, to which the N64 has access via the PI bus. At the moment, romfs does not support directories. The maximum memory size depends on the cartridge board version - 64 MB for version 2 with a soic-8/wson-8 8x6 flash chip package, 128 MB for version 3 with a soic-16 flash chip package.



### Project files



#### Cartridge board version 2 (soic-8/wson-8 8x6 - 64MB max)



[Schematic pdf](hw/n64cart-v2-soic-8.pdf)



[Schematic eagle cad](hw/n64cart-v2-soic-8.sch)



[PCB eagle cad](hw/n64cart-v2-soic-8.brd)



[Gerber files](hw/n64cart-v2-soic-8_2024-08-11.zip)



#### Cartridge board version 3 (soic-16 - 128MB max)



[Schematic pdf](hw/n64cart-v3-soic-16.pdf)



[Schematic eagle cad](hw/n64cart-v3-soic-16.sch)



[PCB eagle cad](hw/n64cart-v3-soic-16.brd)



[Gerber files](hw/n64cart-v3-soic-16_2024-08-11.zip)



### Features



- One user controllable LED, accessible from N64 side, RGB WS2812 for PCB version 3 (all except PicoCart64-lite)



- UART port, accessible from N64 side (all except PicoCart64-lite)



- USB passthrough to N64 side



- Emulation for EEPROM 4/16Kbit



- Emulation for SRAM 256Kbit/1MBit



- USB utility to access to the cartridge flash chip as filesystem.



### Memory mapping



#### Registers:



Register|Address|Mode

--------|-------|----

UART_CTRL|0x1fd01000|R-

UART_RXTX|0x1fd01004|RW

LED_CTRL|0x1fd01008|-W

SYS_CTRL|0x1fd0100c|RW

SSI_SR|0x1fd01010|RW

SSI_DR0|0x1fd01014|RW

FW_SIZE|0x1fd01018|R-



#### UART_CTRL bits:



Function|Bit mask|Mode

--------|--------|----

UART_RX_AVAIL|0x01|R-

UART_TX_FREE|0x02|R-



#### UART_RXTX bits:



Function|Bit mask|Mode

--------|--------|----

DATA|0xFF|RW



#### LED control bits:



Function|Bit mask|Mode|Note

--------|--------|----|---

LED_ONOFF|0x01|-W|PCB v2 or PCB v3 without WS2812

LED_RGB|0x00ffffff|-W|PCB v3 only



#### SYS_CTRL bits:



Function|Bit mask|Mode

--------|--------|----

EEPROM_16KBIT|0x1000|RW

SRAM_UNLOCK|0x100|RW

FLASH_MODE_QUAD|0x10|RW

FLASH_CS_HIGH|0x01|RW



#### SSI_SR bits:



Function|Bit mask|Mode

--------|--------|----

SSI_SR_TFNF_BITS|0x01|R-

SSI_SR_RFNE_BITS|0x02|R-



#### SSI_DR0 bits:



Function|Bit mask|Mode

--------|--------|----

DATA|0xff|RW



## PCB



### Order notes



The thickness of the PCB is 1.2 mm.



Ordering a stencil will make it easier to apply solder paste, but will increase the cost of the order.



### Assembly notes



After soldering, if you have used a flux when soldering a processor or a flash chip, wash it well from the board, otherwise unstable work with memory is possible or it will not work at all.



#### for PCB version 2



Do not solder Q1 if D2 is soldered. Use either D2 or Q1.



Do not solder R1 and R6.



#### for PCB version 3



Do not solder R1 and D2 if LED3 is soldered.



## Build firmware



To build, you will need an installed Pico SDK.



By default, the firmware is compiled for cartridge version 3 and NTSC. Add to cmake ```-DBOARD=v2``` to build it for version 2 (flash chip 32/64 MB). Add to cmake ```-DBOARD=pico``` to build it for generic pico cartridge (flash chip 16 MB or less) without SI_DAT, SI_CLK, NMI, INT lines.

 Add to cmake ```-DBOARD=pico-lite``` to build it for PicoCart64-lite cartridge (flash chip 16 MB or less) with SI_DAT, SI_CLK, NMI, INT lines.



Add to cmake ```-DREGION=pal``` to build it for PAL.



Steps to build:

```

  cd fw



  mkdir build



  cd build



  cmake ..



  make -j

```



Press the cartridge button, connect the cartridge to USB and upload 'n64cart.uf2' to the RPI-RP2 disk.



## Build rom manager



To build, you will need an installed N64 toolchain with [libdragon](https://github.com/DragonMinded/libdragon), compiled in opengl branch.



Add to make ```BOARD=pico``` to build it for generic pico (flash chip 16 MB and less). Add to make ```BOARD=pico-lite``` to build it for PicoCart64-lite (flash chip 16 MB and less).



Steps to build:



```

  cd ../../rom



  make

```



## Cartrigde utility



The utility is used to format cartridge memory, write and read files from cartridge memory. You can upload new roms, change the background pictures with utility.



### Build



To build for linux and Mac OS, you need to install the libusb development files.



```

  cd ../utils



  make

```



For windows, install mingw toolchain.



```

  cd ../utils

  

  make SYSTEM=Windows

```



### How to use



The first time you use a cartridge, you must format it and write a file manager:



```

  ./usb-romfs format



  ./usb-romfs push ../rom/n64cart-manager.z64

```



Upload some other roms, for example:



```

  ./usb-romfs push rodfsdemo.z64

```



Change background image:



```

  ./usb-romfs push picture.jpg background.jpg

```



Full list of the utility commands:



```

./usb-romfs help

./usb-romfs bootloader

./usb-romfs reboot

./usb-romfs format

./usb-romfs list

./usb-romfs delete 

./usb-romfs push [--fix-rom][--fix-pi-bus-speed[=12..FF]] [ ]

./usb-romfs pull [ ]

```



## Total cartridge cost (32MB version)



The price of components for an online order of one or two pieces may be lower

than the cost of delivery. When ordering in several pieces, sometimes there

may even be free shipping.



Seller|Delivery cost|Components

------|-------------|---

[Chicago Electronic Distributors](https://chicagodist.com/)|$6-$11|RP2040

[Arrow](https://www.arrow.com/)|Free for orders > $50|spi flash,resistors,capacitors,etc

[jlpcb](https://jlcpcb.com/)|$22.4|PCB



The price for 5 PCB is $2 ($4 for non first in order position).



The most expensive components:



Component|qty|Price

---------|---|-----

RP2040|1|$1

W25Q256JVEIQ|1|$4.24

ABLS-12.000MHZ-B4-T|1|$0.26

UJ2-MIBH-G-SMT-TR|1|$0.45

LDI1117-3.3U|1|$0.34

BAT60AE6327HTSA1|2|$0.93



All other components (LEDs, resistors, capacitors) from home stock, total cost less than $1.



So, the total cost of the pcb and components is approximately $9.



## Photos version 2



























## BOM list for version 3



Part|Value|Device|Package

----|-----|------|-------

C1|100n|C-EUC0402|C0402

C2|100n|C-EUC0402|C0402

C3|100n|C-EUC0402|C0402

C4|100n|C-EUC0603|C0603

C5|100n|C-EUC0402|C0402

C6|100n|C-EUC0402|C0402

C7|100n|C-EUC0603|C0603

C8|100n|C-EUC0402|C0402

C9|100n|C-EUC0402|C0402

C10|1uF|C-EUC0402|C0402

C11|100n|C-EUC0402|C0402

C12|100n|C-EUC0402|C0402

C13|1uF|C-EUC0402|C0402

C14|100n|C-EUC0402|C0402

C15|27pF|C-EUC0402|C0402

C16|27pF|C-EUC0402|C0402

C22|10u|C-EUC0805|C0805

D1|SL02-GS08|SL02-GS08|SOD-123

D2|GREEN|LED0603|0603

D3|RED|LED0603|0603

IC1|RP2040-QFN56|RP2040-QFN56|QFN-56

LED3|XL-5050RGBC-WS2812B|XL-5050RGBC-WS2812B|XL5050RGBCWS2812B

Q1|BSS84|BSS84|SOT23

R1|1K|R-EU_R0603|R0603

R2|1K|R-EU_R0402|R0402

R3|1K|R-EU_R0402|R0402

R4|27|R-EU_R0402|R0402

R5|27|R-EU_R0402|R0402

R12|1K|R-EU_R0603|R0603

S1||10-XX|B3F-10XX

U$1|LDI1117-3.3U|LDI1117-3.3U|LDI1117-3.3U

U2||USB|USB-MICRO-SMD

U4|MX66L1G45GMI-08G|MX66L1G45GMI-08G|SOP_16

XTAL1|ABLS-12.000MHZ-B4-T|ABLS-12.000MHZ-B4-T|XTAL_ABLS_ABR



## Photos version 3