This project is based upon David Shadoff's ProtoHu. The original Eagle project was converted to KiCad. The most important difference is the addition of an OR gate to fully decode the HuCard address space, such that the image written to the flash is available only in the lower half and not mirrored the the upper one. The motivation for this is for the card to respond to the minimum practical range of addresses in the HuCard space, freeing the upper region such that diagnostic tests may be performed without risk of conflicts with hardware in a real console. Specifically, this card can be flashed with diagnostics for the CD hardware found in a PC Engine/Turb Duo system.
The project consists of two boards: one that features the HuCard connector and all the components, the other being a spacer to fit under the first to give the complete assembly a flat lower surface. The upper board should be 0.8mm thick with at least an ENIG finish for gold plating on the edge connector contacts. A chamfered edge near the connector will improve the fit.
The spacer board should be 1.6mm to clear the height of the components and bring the total up to 2.4mm, which seems to be the nominal dimension of a standard HuCard. As it contains no components, the finish on the spacer boards is not important.
This visual design is intended to look vaguely like an original HuCard when white solder mask is used with black silkscreen.
| Reference | Value | Footprint |
|---|---|---|
| C1,C3 | 0.1uF | 0805 |
| C2 | 1uF | 0805 |
| IC1 | SST39SF040 | SOP-32 |
| IC2 | 74HC32 | TSSOP-14 |
| J2 | 0.1" Header * | DIP-32 |
| R1 | 47K | 0805 |
* It's possible to omit this and program the flash by holding the card firmly against some header pins mounted in your programming device.
Suggested order of operations:
- Populate IC1, IC2, then the passives and finally the header pins.
- Dry fit the two boards to test.
- When satisfied, use CA/super glue or similar to join the two boards. Some areas labeled "GLUE" are left unmasked to ensure direct adhesion to the board substrate, but glue can also be applied anywhere else you deem fit.