Ryan Malloy
48b61f462a
Simulated RX and TX paths via mcltspice, generated 4 SVG waveform plots (2000 data points each), and staged all 8 netlists plus the muki01 schematic as downloadable site assets. Presentation: Starlight Tabs for RX/TX waveform pairs, inline schematic image, dark mode CSS filter for white-background SVGs, and netlist inventory with download links.
66 lines
1.7 KiB
Plaintext
66 lines
1.7 KiB
Plaintext
* BMW I/K-Bus Interface - RX Path (Bus to ESP32) - PC817 Optocoupler
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* Bus drives byte 0x50 (MFL addr) at 9600 baud 8E1
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* 0x50 = 01010000, LSB first = 00001010, even parity = 0
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* Frame: START(0) d0(0) d1(0) d2(0) d3(0) d4(1) d5(0) d6(1) d7(0) P(0) STOP(1)
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* Bus: 12V=idle/HIGH, 0V=active/LOW, bit time=104.17us
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* ESP32 GPIO thresholds: LOW < 0.825V, HIGH > 2.475V
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*
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* PC817 pin order: 1=Anode, 2=Cathode, 3=Collector, 4=Emitter
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* U1 config: emitter-follower (collector to VCC, emitter to RX output)
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* === Power Supplies ===
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V_BAT V12 0 12
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V_MCU VCC 0 3.3
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* === Bus Model ===
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* External module driving byte 0x50 through 100R source impedance
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V_BUS V_BUS_SRC 0 PWL(
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+ 0u 12
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+ 199.5u 12
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+ 200u 0
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+ 720.33u 0
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+ 720.83u 12
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+ 824.5u 12
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+ 825u 0
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+ 928.67u 0
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+ 929.17u 12
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+ 1032.83u 12
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+ 1033.33u 0
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+ 1241.17u 0
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+ 1241.67u 12
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+ 2000u 12)
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R_BUS V_BUS_SRC IBUS 100
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C_BUS IBUS 0 100p
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* === RX Optocoupler (U1) ===
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* Bus HIGH (12V): LED on -> phototransistor ON -> RX HIGH
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* Bus LOW (0V): LED off -> phototransistor OFF -> RX LOW (via R4)
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R1 IBUS U1_A 2k
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XU1 U1_A 0 VCC RX PC817 Igain=1m
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R4 RX 0 1k
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* === PC817 Subcircuit (inlined from LTspice library) ===
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.subckt PC817 1 2 3 4
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R1 N003 2 2
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D1 1 N003 LD
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G1 3 N004 N003 2 {Igain}
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C1 1 2 18p
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Q1 3 N004 4 [4] NP
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.model LD D(Is=1e-20 Cjo=18p)
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.model NP NPN(Bf=1200 Vaf=140 Ikf=100m Rc=1 Cjc=19p Cje=7p Cjs=7p C2=3e-15)
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.ends PC817
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* === Simulation ===
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.tran 0 2000u 0 0.1u
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* === Measurements ===
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.meas tran RX_HIGH MAX V(RX)
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.meas tran RX_LOW MIN V(RX)
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.meas tran IBUS_HIGH MAX V(IBUS)
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.meas tran IBUS_LOW MIN V(IBUS)
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.meas tran LED_CURRENT_MAX MAX I(R1)
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.meas tran RX_RISE TRIG V(RX) VAL=0.825 RISE=1 TARG V(RX) VAL=2.475 RISE=1
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.meas tran RX_FALL TRIG V(RX) VAL=2.475 FALL=1 TARG V(RX) VAL=0.825 FALL=1
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.backanno
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.end
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