Mini LHC Display

The CERN Mini LHC Display will be a prototype display board for the CERN Mimic Panel. Since the final LHC board will be large and therefore expensive, I'm starting with a mini version which can test the overall architecture but be smaller if it requires a re-spin.

Status

• 2025-05-29: Routed the 7-segment displays to the AS1115, only pins not yet routed are the AS1115 to the MCU. Started thinking about how best to route the +15V around the ring, decided on a circle trace on the bottom, via'ed up to each LED. Started laying this out.
• 2025-05-27: Finished routing the Beam Mode and Accelerator Mode busses between the displays and to the translator chips (I think), whew! Next up is probably the 7-segment displays. Nothing is connected to the MCU yet, I'll tackle that once the 7-segs are done.
• 2025-05-25: Did lots more work on PCB layout, both regulators are laid out, general locations of major components are tentatively laid out, and started putting smaller details together. Switched LEDs from 0603 to 1206, as the former looked too small once I started laying things out.
• 2025-05-20: Started PCB layout! Drew the overall beam rings and tunnels and started laying LEDs out along them.
• 2025-05-19: Removed integrated regulator modules and designed discrete DC-DCs to replace them, one each for 3.3v and 5v. Replaced link connector with SMD version, and completed schematic checklist.
• 2025-05-18: Finished adding test points and checklisting. Generated starting PCB layout, but realized the regulators and link connector are through-hole, and I'd intended for 100% SMD components so they can go on the back and the front can be a clean display. I'll look at other options for those before I proceed on the layout.
• 2025-05-17: Finished integrating the LCD, drew footprints for things that were missing them, and completed footprint assignment. Started putting in test points, finishing that then doing the checklist is next.
• 2025-05-16: Finished connecting up the misc. LEDs, picked the EA-DOGL128 LCD for the Page 1 comment, and started the schematic page for that.
• 2025-05-13: Put schematic together for the beam LEDs, and started putting schematic together for the misc. LEDs. Had slightly too many LEDs on the "misc" TLC5955, so merged the two Beam Permit Link LEDs into one (these are essentially always both true or always both false so this should be fine) and lowered the TI LEDs from 4 for each tunnel to 3, so now we have exactly 48 LEDs on that one.
• 2025-05-12: Put design and schematic together for driving the energy and t(SB) displays, using an AS1115.
• 2025-05-10: Started putting BOM and schematic together, got the alphanumeric accel/beam display circuitry all laid out.
• 2025-04: Started putting design thoughts together

Design Thoughts

• discrete LEDs
  • beam LEDs for B1/B2 (24 each, 48 total)
  • beam IP LEDs (4 RGB, 12 channels total)
  • TI LEDs (4 per beam, 8 total)
  • dump LEDs (2 plus one RGB per beam, 10 channels total)
  • cryo status wrapup LED (1 bicolour, 2 channels total)
  • collimator status wrapup LED for each beam (2 bicolour, 4 channels total)
  • BIS/SMP - beam permit, movables allowed in, stable beams, permit link (4 bicolor)
• energy display (4x 7-segment LEDs)
• t(SB) display (hh:mm - 4x 7-segment LEDs plus a colon)
• 2x TLC5955
• 1x AS1115 for 7-segment displays
• 16x2 LED dot matrix displays for beam/accel status (built-in smarts, so no TLC5955 required)
• Would like a little LCD like the final one will have for displaying the Page1 comment, will see if there's space later on

MCU Needs

• I2C for link to controller
• SPI + 4 CS = 7 total pins for TLC5955s
• Shared SPI + 1 CS = 1 extra pin for AS1115
• 19 I/Os + 4 CSs = 23 total pins for dot matrix displays
• ~33 I/Os total