Nova64 Cartridge Pinout Overview

This document provides a compact, high-level technical view of the Nova64 cartridge connector from the cartridge developer perspective.

Purpose

A concise 32-pin cartridge interface for expansion modules, storage, I/O, and optional power delivery.

Pin	Signal	Role	Default idle state
1	GND	ground	grounded
2	VCC_3V3	supply	N/A
3	CARTRIDGE_DET	cartridge presence detect	pull-up
4	POWER_CTRL	power direction control	pull-down
5	USB_FLAG	USB-capable flag	pull-up
6	USB_DP	USB D+	pull-down
7	USB_DM	USB D-	pull-down
8	USB_ID	USB host/device mode	pull-up
9	USB_VBUS	VBUS sense / optional power	pull-down
10	SD_CMD	SDMMC command / host->cartridge control	pull-up
11	SD_CLK	SDMMC clock / host->cartridge	pull-down
12	SD_D0	SDMMC data0 (bi-directional)	pull-up
13	SD_D1	SDMMC data1 (bi-directional)	pull-up
14	SD_D2	SDMMC data2 (bi-directional)	pull-up
15	SD_D3	SDMMC data3 (bi-directional)	pull-up
16	I2C_SCL	I2C clock	pull-up
17	I2C_SDA	I2C data	pull-up
18	I2S_SCLK	I2S bit clock	pull-down
19	I2S_WS	I2S word select / frame clock	pull-down
20	I2S_SDOUT	I2S data out (cartridge->host)	pull-down
21	I2S_SDIN	I2S data in (host->cartridge)	pull-down
22	I2S_MCLK	I2S master clock	pull-down
23	SPI_MOSI	SPI MOSI (host->cartridge)	pull-down
24	SPI_MISO	SPI MISO (cartridge->host)	pull-down
25	SPI_SCLK	SPI clock (host->cartridge)	pull-down
26	SPI_CS0	SPI chip select (host->cartridge)	pull-down
27	CAN_H	CAN high	recessive bias
28	CAN_L	CAN low	recessive bias
29	UART_RX	UART RX (host->cartridge)	pull-up
30	UART_TX	UART TX (cartridge->host)	pull-up
31	VCC_5V	supply	N/A
32	GND	ground	grounded

Keep storage and interface signals separate from power.
Reserve the SDMMC channel so cartridges can provide their own software/data layer.
Include USB and serial buses for smart module support.
Use a dedicated ID input for simple cartridge recognition.
Provide optional audio and GPIO for versatile cartridge types.

This is a high-level connector map, not a full electrical specification.
Exact pin assignments may be refined later during hardware design.
Preferred placement for pull-ups / pull-downs is the main device, with cartridge-side resistors only used for optional or cartridge-specific functions.
Cartridge presence should be detected via a dedicated CARTRIDGE_DET pin, not by ORing multiple ID signals.
Cartridge features such as SD/storage, I2C, SPI, CAN, UART and audio should be discovered dynamically at runtime after insertion.
For bidirectional power delivery, the system should use a dedicated power-path controller and a clear source priority scheme.
- Monitor main device and cartridge voltage presence before enabling any power path.
- Use POWER_CTRL as a control input for a power-path switch or enable pin, not as a current-carrying line.
- If the main device is powered and the cartridge is not actively supplying power, keep cartridge supply disabled.
- If the main device is unpowered and a powered cartridge is inserted, allow the cartridge to supply the system after voltage stability is confirmed.
- Prevent backfeed by using ideal diodes or bidirectional power-path ICs that only conduct from the active source.

Suggested cartridge categories:

Category	Meaning
software only	cartridge provides software/application data only
special hardware	cartridge includes additional hardware functions
dynamic detection	actual capabilities are determined at runtime after insertion

USB_FLAG = 1 indicates the cartridge can present USB functionality in addition to its category.

POWER_CTRL = 1 indicates the cartridge provides power to the main device

A short technical reference for the Nova64 cartridge connector, intended for initial design discussion.