87caa933ea
Heirloom pro-audio modular brain/face design captured under hardware/: - DESIGN.md: full spec (RP2350, ±15V studio rails via TPS65131+TPS7A LDOs, PCM5102A click, THAT1240/1646 balanced click-injector with switchable protected line/instrument input, fail-safe mute relay, series ground-lift, USB-MIDI default + DNP hardware MIDI, sig/clip detect, ESD/EMI, chassis), plus the two-interconnect pinouts (Pico-compatible digital ribbon + separate analog/MIDI). - BOM.csv: manufacturer part numbers + rough costs. - kicad/: valid KiCad 7 project + documented schematic canvas. PCB layout/routing remains the interactive step. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
56 lines
3.9 KiB
Text
56 lines
3.9 KiB
Text
(kicad_sch (version 20230121) (generator eeschema)
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(uuid 743b8308-6a69-48de-a6ff-2336bc6c804f)
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(paper "A3")
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(title_block
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(title "PM_K-1 Core Board (brain) - VARASYS PolyMeter")
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(date "2026-05-30")
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(rev "A")
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(company "VARASYS")
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(comment 1 "Heirloom pro-audio modular core: RP2350 + +/-15V studio audio + balanced click-injector")
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(comment 2 "Design-of-record canvas - see hardware/DESIGN.md. Symbol placement + wiring = interactive TODO in Eeschema.")
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)
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(lib_symbols)
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(text "PM_K-1 CORE BOARD (\"brain\")\nHeirloom pro-audio modular core - design-of-record canvas.\nFull spec, BOM and interconnect pinouts: hardware/DESIGN.md + hardware/BOM.csv."
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(uuid 00109097-7760-4eb7-b299-bd3f64383aab)
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(text "POWER TREE\nUSB-C 5V -> AP2112K 3V3 (digital IO)\nRP2350 internal SMPS -> 1.1V core (ext L)\nTPS65131 dual boost/inverter -> raw +/-18V\nTPS7A4901 / TPS7A3001 LDO -> CLEAN +/-15V (audio)\nStar ground; switcher in a guarded corner."
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(text "MCU + DIGITAL\nRP2350A (QFN-60) - mind E9 erratum: external pulldowns on read inputs.\nW25Q128JV 16MB QSPI flash (wear-leveled).\n12MHz crystal. SWD 2x5 + labeled test points.\nI2S BCK/LRCK/DOUT + low-jitter 24.576MHz MCLK stay ON-CORE."
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(text "CLICK SOURCE\nPCM5102A I2S DAC (Burr-Brown).\nFed by dedicated low-jitter audio XO (ASEM1-24.576MHz),\nnot PIO-jittered MCLK."
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(text "ANALOG INPUT (switchable line / instrument)\nProtection (non-negotiable): series DC-block film cap (blocks +48V phantom),\nclamp diodes/TVS to rails, series current-limit R.\nLINE: THAT1240 balanced receiver (laser-trimmed CMRR).\nINST: OPA1641 JFET Hi-Z buffer (>=1Mohm) + ~+10..15dB gain.\nK1 gold relay selects path (GPIO; touchscreen or optional face switch)."
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(uuid 737ed14f-66db-4799-a337-21438143ce09)
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(text "MIX + OUTPUT\nMix = digital/firmware (click level via DAC); analog stage at unity.\nTHAT1646 balanced driver + 47ohm build-out per leg.\nOutput level: Bourns 3296W 25-turn trim -> DAC FS = +4dBu (~+24dBu headroom).\nMUTE relay K2: fail-safe (de-energized = muted); HW supervisor, not MCU-dependent.\nGROUND-LIFT: face panel switch IN SERIES with core relay K3; soft-lift 100ohm||10nF.\nNO electrolytics in signal path - WIMA film caps, 0.1% thin-film R."
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(uuid 99fe482f-1fde-4dd1-9579-56113dcb21bc)
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(text "INDICATORS / MIDI / SPEAKER\nSIG/CLIP: peak detect -> LM393 -> RP2350 GPIO (UI) + LED lines on interconnect.\nMIDI: USB-MIDI default (firmware). DNP hardware option: H11L1 opto IN + 74LVC14 OUT/THRU.\nSpeaker: PAM8302 class-D, DNP per form factor.\nESD/EMI: USBLC6-2 on USB + CM choke; series R + ESD arrays on interconnect; ferrites at analog crossing."
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(uuid 03eeefa8-7728-4e14-90c0-6d0496a0d207)
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(text "INTERCONNECTS (see DESIGN.md s7)\nJ2 DIGITAL RIBBON 2x13 - Pico-pinout-compatible (SPI/I2C/ADC/buttons/LED + GNDLIFT_SW/LINEINST_SW/SIG_LED/CLIP_LED).\nJ3 ANALOG 2x5 - AOUT H/C, AIN H/C, AGND, CHASSIS/SHIELD, SPK+/- (DNP). Kept away from the fast digital ribbon.\nJ4 MIDI 1x6 - OUT A/B, IN A/B, +5V, GND (only if DNP MIDI populated).\nRelays + I2S + MCLK are core-only and NOT on the ribbon; a Pico test brain drives digital I/O but not the analog chain."
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(sheet_instances
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(path "/" (page "1"))
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