SD2IEC

Rev A September 2022

Basic Tests: works, with flaws

This version was built and minimal tests were performed. The footprint for the DIN connectors is wrong. Don't put in the DIN connectors. The alternate footprints are fine, I used a cable with a JST connector on one side and a male DIN on the other.

Rev B will have a corrected footprint and maybe more IO connectors (serial, LCD connectors were left out due to routing headache)

You can quote me on this:

Triple check your footprints with the real things. Don't blindly trust a footprint diagram found on AliExpress - me

Description

Yet another varion of the SD2IEC hardware device. From the wiki:

The SD2IEC is a mass storage device using an SD/MMC card and interfacing with the IEC bus. It is based on the ATmega644 microcontroller from the Atmel AVR microcontroller family. The most prominent use of SD2IEC is replacement of a Commodore-1541 disk drive for a C64. The hardware and the microcontroller sd2iec firmware are available as open source

Compatible with C64, C64DTV, C128 (no burst mode), C16, VIC-20, etc.

Features of this version:

• Nothing fancy, there are 1001 version out there, it's just mine
• ATmega1284p
  • more headspace
• Reset button
  • only resets the drive, not the whole computer nor the other drives
• Full size SD slot
  • ...which happens to be one I had on hand, so triple check the layout (holes and pads on the side) to see if it will fit with yours
• Prev / Next buttons
  • Not even sure what they do, need to check the doc
• Device selection DIP switches (8-11)
• Red / Green LEDs for activity, red flash on error, etc.
• Voltage regulator
  • MIC5504-3.3YM5 LDO regulator
    • can probably be swapped with another regulator with same footprint
    • don't put in more than ~6V (5.5 regulator max + diode drop)
    • ...or less than 4V
  • Powers from the 5V on the datasette connector (optional).
  • Can solder alternate 5V power source on pads 1 & 2
  • I'll put in an alternate pin header in RevB...
• Two DIN connectors with passthrough, so you can daisy chain with another drive or more.
  • The footprint for the DIN connector is wrong in RevA, don't use it
• Alternate footprint for the two IEC connectors: Can solder in 2.54mm pin headers instead of the DIN connectors
  • I put a JST connector in there
  • Again, don't use the DIN connectors with RevA!
• The IEC lines are switched with MOSFETS (AO3400A)
  • ...which are not recommended for new designs and surely out of stock everytwhere (everything is at the moment). There are probably direct replacements
• Fancy tantalum capacitors which are surely overkill. Not sure what I was thinking. Don't put 'em backwards

Images

Front	Back

Schematics (pdf)

• Complete schematics

PCB Images (svg)

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