================================================================================ TM-VCAP-SCH-003 Rev A CYD DISPLAY INTERFACE — VARIABLE CAPACITOR TUNER ESP32-2432S028R (CYD) Schematic Reference ================================================================================ 1. CYD HARDWARE OVERVIEW ========================== ESP32-2432S028R ("CYD" = Cheap Yellow Display) ┌──────────────────────────────────────────────────────────┐ │ ILI9341 TFT 320×240 pixels 2.8" RGB-565 color │ │ XPT2046 Resistive Touch 4-wire SPI │ │ ESP32-WROOM-32 on board │ │ USB-C for power + programming │ │ GPIO expander: CN1 header (GPIO 21,22,35,36,39) │ │ MicroSD socket (not used in this project) │ │ RGB LED on GPIO 4(B), 16(G), 17(R) │ │ Bluetooth Classic (BT serial) for data from ESP32 tuner │ └──────────────────────────────────────────────────────────┘ Connection to ESP32 Tuner board: CYD receives data FROM tuner via Bluetooth Serial (no wires needed) CYD can optionally connect to Wi-Fi to access /api/status endpoint BT Packet format (ASCII, 160 bytes max, newline-terminated): "BAND:%s,TYPE:%d,C_PF:%.1f,ANGLE:%.1f,SWR:%.2f,FWD:%.3fW,STATE:%d,STEP:%d\n" 2. CYD TFT CONNECTION (internal to CYD board) =============================================== ESP32 → ILI9341 (hardwired on CYD PCB): GPIO 02 → TFT_DC (data/command select) GPIO 15 → TFT_CS (chip select) GPIO 13 → TFT_MOSI (SPI data) GPIO 14 → TFT_SCK (SPI clock) GPIO 12 → TFT_MISO (not needed for write-only) GPIO 21 → TFT_BL (backlight, PWM-controllable) Touch (XPT2046): GPIO 33 → TOUCH_CS GPIO 36 → TOUCH_IRQ (input only) (shares SPI bus with TFT but different CS) 3. PAGE LAYOUT REFERENCE ========================== ┌────────────────────────────────────────────────────────────────────┐ │ PAGE 0: CAPACITANCE / SWR │ ├────────────────────────────────────────────────────────────────────┤ │ ┌──────────────────────────┐ ┌─────────────────────────────┐ │ │ │ BAND │ │ STATE │ │ │ │ 20m 14.175 MHz │ │ LOCKED / TUNING / IDLE │ │ │ └──────────────────────────┘ └─────────────────────────────┘ │ │ │ │ CAPACITANCE ANGLE │ │ ┌──────────────┐ ┌──────────────┐ │ │ │ 55.2 pF │ │ 90.0° │ │ │ └──────────────┘ └──────────────┘ │ │ (large green font) (large cyan font) │ │ │ │ SWR: 1.15 FWD: 98.3W │ │ ████████░░░░░░░░░░░░░░░░░░░░ (SWR bar, green < 1.5) │ │ │ │ [◄ PREV PAGE] [NEXT PAGE ►] │ └────────────────────────────────────────────────────────────────────┘ ┌────────────────────────────────────────────────────────────────────┐ │ PAGE 1: CAP DESIGN INFO │ ├────────────────────────────────────────────────────────────────────┤ │ DESIGN: VC-HF100 n_plates: 14R + 15S │ │ Plate r: 30mm Spacing: 1.5mm │ │ C range: 10–225 pF V_work: 1500V pk │ │ Q(14MHz): 600 SRF: 150 MHz │ │ Frame: 80×80×70mm Material: Brass/Delrin │ │ │ │ Band capacitance targets (auto-populated from band table): │ │ 160m:220pF 80m:200pF 40m:120pF 30m:85pF 20m:55pF │ │ │ │ [◄ PREV PAGE] [NEXT PAGE ►] │ └────────────────────────────────────────────────────────────────────┘ ┌────────────────────────────────────────────────────────────────────┐ │ PAGE 2: POWER ANALYSIS │ ├────────────────────────────────────────────────────────────────────┤ │ FWD POWER: 98.3 W │ │ REFL POWER: 2.1 W │ │ SWR: 1.15 │ │ │ │ EST. CAP VOLTAGE PEAK: │ │ ┌──────────────────────────────────────────────────────┐ │ │ │ At 55pF, 14MHz: X_C=206Ω │ │ │ │ I_peak = √(2×98.3/50) = 1.98A │ │ │ │ V_C_peak = 1.98 × 206 = 407V (27% of 1500V limit) │ │ │ │ ████████░░░░░░░░░░░░░░░░░░░░░░ SAFE │ │ │ └──────────────────────────────────────────────────────┘ │ │ │ │ [◄ PREV PAGE] [NEXT PAGE ►] │ └────────────────────────────────────────────────────────────────────┘ ┌────────────────────────────────────────────────────────────────────┐ │ PAGE 3: OPERATING GUIDE │ ├────────────────────────────────────────────────────────────────────┤ │ PROCEDURE: │ │ 1. Select band with BTN_BAND_UP/DN on tuner │ │ 2. Set RF power to 5-10W (reduce power for tuning) │ │ 3. Press TUNE button OR web /tune endpoint │ │ 4. Tuner scans capacitance range → finds min SWR │ │ 5. STATE changes: IDLE → TUNING → LOCKED │ │ 6. When LOCKED: increase to full power │ │ │ │ CAUTION: At 100W on 160m/80m, verify cap V-rating │ │ for your circuit Q before transmitting! │ │ │ │ [◄ PREV PAGE] [NEXT PAGE ►] │ └────────────────────────────────────────────────────────────────────┘ Touch zones: LEFT 80px = prev page; RIGHT 80px = next page Center zone: (future) direct band select 4. BT PACKET PARSING REFERENCE ================================ Packet transmitted by ESP32 tuner at BT_INTERVAL_MS (200ms default): "BAND:%s,TYPE:%d,C_PF:%.1f,ANGLE:%.1f,SWR:%.2f,FWD:%.3fW,STATE:%d,STEP:%d\n" Example: "BAND:20m,TYPE:1,C_PF:55.2,ANGLE:90.0,SWR:1.15,FWD:98.300W,STATE:2,STEP:399\n" Parse in CYD firmware with sscanf: sscanf(buf, "BAND:%7[^,],TYPE:%d,C_PF:%f,ANGLE:%f,SWR:%f,FWD:%fW,STATE:%d,STEP:%d", data.band, &data.cap_type, &data.C_pF, &data.angle_deg, &data.swr, &data.fwd_watts, &data.state, &data.step_count); STATE values: 0 = IDLE (no RF; motor at rest) 1 = TUNING (motor moving; scanning for SWR minimum) 2 = LOCKED (SWR < SWR_GOOD; motor holding position) 3 = HOMING (homing cycle running; do not transmit) TYPE values (CapDesign enum): 0 = CAP_QRP (10–350 pF, 200V) 1 = CAP_HF100 (10–225 pF, 1500V) 2 = CAP_TX (5–84 pF, 4000V) 3 = CAP_VHF (2–47 pF, 500V) 4 = CAP_UHF (0.5–12 pF, 200V) ================================================================================ END TM-VCAP-SCH-003 ================================================================================