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# ULX3S PCB
This is work-in-progress place for putting
some wishes of a small (94x51 mm) FPGA board.
Instead of describing in written,
it is better explained when drawn in kicad:
kicad ulx3s.pro
[Schematics](/doc/schematics.pdf) is mostly complete.
PCB routing is complete, but needs improvement
mainly for the power supply.
3D preview
![TOP](/pic/ulx3st.jpg)
![BOTTOM](/pic/ulx3sb.jpg)
# Features
FPGA: Lattice ECP5 LFE5U-25F-6BG381C
USB: FTDI FT231XS (1Mbit JTAG and 3Mbit usbserial)
GPIO: All differential, PMOD-friendly
RAM: 32MB SDRAM MT48LC16M16
Flash: 8MB SPI flash S25FL164 for FPGA config
Storage: Micro-SD slot
LEDs: 10 (8 blink-LEDs, 2 USB leds)
Buttons: 6 (4 direction and 2 fire buttons)
Audio: 3.5 mm stereo jack
Video: GPDI connector with 3.3V-5V I2C bidirectional level shifter
Display: placeholder for 0.96-1.3" SPI OLED COLOR or B/W
WiFi+bluetooth: placeholder for ESP-32 (JTAG and serial over WiFi possible)
Power: 3 Switching voltage regulators: 1.2V, 2.5V, 3.3V
Low power sleep: RTC clock wakeup, quartz and battery
GPDI is General Purpose Differential Interface,
Electrically LVDS, mostly TMDS tolerant
female receptacle more-or-less compatible
with digital monitors/TVs
# Todo
Finish routing and especially improve Power
section (thicker power lines, separately routed feedback)
2.54 mm external JTAG header
[ ] move USB LEDs from bottom to top side
[ ] increase thickness of power lines (5V, 3.3V, 2.5V)
[ ] compile a f32c bitstream using the schematics
[ ] connect more lines from ESP-32 to FPGA
[ ] connect FPGA USB D+/D- with 1.5k pullup in USB 1.1 (full speed) mode
[ ] Jumpers to switch 2.5V/3.3V for left IO banks