4 layers243.8 × 171.5 mm
2 layers125 × 58 mm
ACSI2STM MegaSTE
retro16/acsi2stm212Atari ST ACSI to SD card converter with a STM32
- Size
- 125 × 58 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 17
- Nets
- 47
- Pads
- 118
- Tracks, vias
- 168, 10
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 6 (file 20211014)
- Created
- 23 Feb 2019
- Updated
- 24 Mar 2025
Overview
ACSI2STM MegaSTE is an open-source printed circuit board by retro16, from the retro16/acsi2stm repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 125 × 58 mm with 17 parts on 47 nets, routed with 168 tracks and 10 vias.
It is built around the GSD090012SEU. Its parts include 3 connectors, 2 capacitors, 1 IC and 1 diode. It belongs with the retro computing and games boards of this library.
Main components
1README
pcb/MegaSTE Internal/README.mdACSI2STM-MSTE
This a KiCAD (6.0) design to host an ACSI2STM directly inside an Atari Mega STE using the internal connector. The PCB has been designed to accomodate version 2.x and 3.x of ACSI2STM (aka V2) but also the old V1 design.
- No external power is required, the 5v is taken directly from the internal ACSI connector, but this has only been tested with a fully recapped PSU.
- A set of jumper needs to be soldered to configure the board for V1 or V2 as noted on the PCB.
BOM
- 100 nF Capacitor
- 10uF Radial Capacitor
- Male 2.54 header (Optional)
- 1N5817 Diode
- Female 2.54 headers
- Amphenol GSD090012SEU SD Card socket
- STM32F103C8T6 "Blue Pill" (original one is highly recommended!!!).
- Firmware from ACSI2STM
Configuration
Configuration is done by simple solder bridges on the pads, instructions are also written on PCB.
For V1:
- Solder bridge: JP1, JP2, JP3, JP4, JP5, JP6, JP7
- Solder bridge pads 1 and 2 of JP9 (2 leftmost pads)
- Solder bridge pads 1 and 2 of JP10 (2 leftmost pads)
For V2:
- Solder bridge pads 2 and 3 of JP9 (2 leftmost pads)
- Solder bridge pads 2 and 3 of JP10 (2 leftmost pads)
For V3:
- Solder bridge pads 2 and 3 of JP9 (2 leftmost pads)
- Solder bridge pads 2 and 3 of JP10 (2 leftmost pads)
- Solder bridge JP8
Firmware update
A male 3 pin header is optional and only required if you want to program the STM32 without removing it from the Atari. The RX and TX marking correspond to the STM32 pins A10 an A09, to program the STM32 connect the board's RX to your USB-TTL TX and the board's TX to your USB-TTL-RX:
| USB-TTL | ACSI2STM |
|---|---|
| GND | GND |
| RX | TX |
| TX | RX |
In order to update the STM32:
- Power-off your MegaSTE
- Plug the GND, RX and TX to your USB-TTL adapter
- Move BOOT0 jumper to "1" on the BluePill
- Plug USB to ACSI2STM
- Follow the normal update process.
- Unplug USB, RX, TX and GND
- Move BOOT0 jumper back to original position
- Power-on the Mega STE
:warning: Although the diode should avoid USB power from flowing back to the Mega STE, I haven't tested USB plugged-in while the MegaSTE is powered on. :warning:
Parts
17| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | Close = V1 | Jumper:SolderJumper-2_P1.3mm_Open_Pad1.0x1.5mm | JP1, JP2, JP3, JP4, JP5, JP6, JP7 |
| 1 | 100nF | Capacitor_THT:C_Disc_D4.3mm_W1.9mm_P5.00mm | C1 |
| 1 | 10uF | Capacitor_THT:C_Radial_D5.0mm_H5.0mm_P2.00mm | C2 |
| 1 | 1N5817 | Diode_THT:D_DO-41_SOD81_P10.16mm_Horizontal | D1 |
| 1 | ACK Jumper | Jumper:SolderJumper-3_P1.3mm_Open_RoundedPad1.0x1.5mm | JP10 |
| 1 | BluePill | footprints:YAAJ_BluePill_1 | U1 |
| 1 | Conn_01x03_Male | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J3 |
| 1 | GSD090012SEU | SamacSys_Parts:GSD090012SEU | J2 |
| 1 | Mega STE Internal ACSI | Connector_PinSocket_2.54mm:PinSocket_2x15_P2.54mm_Vertical | J1 |
| 1 | RST Jumper | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP8 |
| 1 | XHDINT Jumper | Jumper:SolderJumper-3_P1.3mm_Open_RoundedPad1.0x1.5mm | JP9 |
Questions
How big is the ACSI2STM MegaSTE PCB?
It measures 125 × 58 mm and has 2 copper layers, 1.6 mm thick.
What parts does the ACSI2STM MegaSTE use?
17 parts, built around the GSD090012SEU. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the ACSI2STM MegaSTE KiCad files?
From the retro16/acsi2stm repository on GitHub, at the commit this page was made from: the board is pcb/MegaSTE Internal/ACSI2STM MegaSTE.kicad_pcb and its schematic pcb/MegaSTE Internal/ACSI2STM MegaSTE.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the ACSI2STM MegaSTE design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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