Raspberry Pi Zero HAT PCB Design
VIN_6V, GND, TPS56339 buck/BOOT/SW/FB, TPS259531 eFuse, motor MOSFET channels, LED JSTs, TP3, and the final ERC checklist.VIN_6V, buck/eFuse-to-PI_5V, motor low-side switching, LED GPIO connectors, and common GND are all largely in place. Remaining issues are cleanup/ERC hygiene: label the unnamed VIN_6V, BUCK_5V, and GND nets, rename AUTO_NAME to Q2_GATE, mark J6:C NC, resolve/assign TP1–TP4 and 6V:P1, then route the PCB airwires. Full audit is in Schematic Audit — Check My Work.CODE_STYLE.VIN_6V = raw protected/usable 6 V input rail after the barrel jack pin A rail definition.GND = single common ground.SW = TPS56339 switch node.BOOT / BOOT_CAP = bootstrap drive/cap node if R9 is used in series.BUCK_5V = TPS56339 regulated output, target about 5.2 V.U1_IN = eFuse input after F2.PI_5V = eFuse protected output to Raspberry Pi 5 V pins.PWM10, Q1_GATE, PWM17, Q2_GATE.MOTOR1_LOW, MOTOR2_LOW.GPIO24_LED, GPIO25_LED.J6:C as No Connect unless intentionally used as a plug-detect/switch pin.VIN_6VJ6:AU2:VINU2:ENC1:P1C2:P1C6:1D5:K if D5 is the VIN TVS/clampJ1:P2 motor connector positiveJ2:P2 motor connector positiveD2:K flyback diode cathode for motor channel 1D3:K flyback diode cathode for motor channel 2GNDJ6:BU2:GNDC1:P2C2:P2C6:2D5:A if D5 is the VIN TVS/clampH1:Pin_6, H1:Pin_9, H1:Pin_14, H1:Pin_25, H1:Pin_34, H1:Pin_39Q1:SQ2:SR3:2R4:2R7:P2C3:2C4:2D1:2 if D1 is the PI_5V TVS/clamp to groundU1:GNDU1:EPR_ILM:P2J5:Pin_2J7:Pin_2J6:C -> No Connect, unless intentionally used for plug detect.R6 = 76.8 kOhm top and R7 = 10 kOhm bottom.VIN_6V:U2:VIN -> VIN_6VU2:EN -> VIN_6V for always-on buck behaviorU2:GND -> GNDSWU2:SWL2:1C5:P2L2:1 must be on this SW net.U2:BOOT -> R9:1 on net BOOTR9:2 -> C5:P1 on net BOOT_CAPC5:P2 -> SW net (U2:SW, L2:1)BOOT and SW.BUCK_5VL2:2C3:1C4:1F2:1R6:1C3:2 -> GNDC4:2 -> GNDFBU2:FBR6:2R7:P1R6:1 -> BUCK_5VR7:P2 -> GNDBUCK_5V -> F2 -> U1_IN -> U1 eFuse -> PI_5V -> H1 pins 2 and 4.BUCK_5V to fuseF2:1 -> BUCK_5VU1_INF2:2U1:3U1:4U1:EN/UVLOPI_5VU1:OUTH1:Pin_2H1:Pin_4D1:1 if D1 is the PI_5V TVS/clamp nodeD1:2 -> GNDU1:ILM -> R_ILM:P1R_ILM:P2 -> GNDR_ILM = 1.0 kOhm, about 2.04 A using ILIMIT = 2000/RILM + 0.04.C7 = 3.3 nF.U1:dVdt -> C7:P1.C7:P2 -> GND.R10 = 100 kOhm.U1:~FLT -> R10:P1.R10:P2 -> PI_5V.U1:dVdt and U1:~FLT as No Connect only if the TPS259531 datasheet allows those pins to float in your configuration.Q1 and connector J2 based on the current net mapping.J2:P2 -> VIN_6V motor positiveJ2:P1 -> MOTOR1_LOW motor negative/switched nodeMOTOR1_LOWJ2:P1Q1:DD2:AQ1:S -> GNDD2:K -> VIN_6VD2:A -> MOTOR1_LOWPWM10 source net:H1:Pin_19 -> R1:1Q1_GATE net:R1:2R3:1Q1:GR3:2 -> GNDQ2 and connector J1 based on the current net mapping.J1:P2 -> VIN_6V motor positiveJ1:P1 -> MOTOR2_LOW motor negative/switched nodeMOTOR2_LOWJ1:P1Q2:DD3:AQ2:S -> GNDD3:K -> VIN_6VD3:A -> MOTOR2_LOWPWM17 source net:H1:Pin_11 -> R2:2Q2_GATE net:R2:1R4:1Q2:GR4:2 -> GNDH1:Pin_18 -> J5:Pin_1 on net GPIO24_LEDJ5:Pin_2 -> GNDH1:Pin_22 -> J7:Pin_1 on net GPIO25_LEDJ7:Pin_2 -> GNDTP3 is a single-pin net on Net 22.TP3 to that intended net, such as BUCK_5V, PI_5V, VIN_6V, PWM10, or PWM17.VIN_6V contains J6:A, U2:VIN, U2:EN, input cap positives, motor positives, and flyback cathodes.GND is a single common ground containing J6:B, Pi GND pins, U2 GND, U1 GND/EP, MOSFET sources, cap returns, resistor pulldowns, and LED connector pin 2s.SW contains exactly U2:SW, L2:1, C5:P2.U2:BOOT -> R9 -> C5:P1, and C5:P2 -> SW.BUCK_5V contains L2:2, C3:1, C4:1, F2:1, R6:1.FB contains U2:FB, R6:2, R7:P1; R7:P2 is GND.U1_IN contains F2:2, U1:3, U1:4, U1:EN/UVLO.PI_5V contains U1:OUT, H1:Pin_2, H1:Pin_4, and the PI_5V clamp node if used.MOTOR1_LOW contains J2:P1, Q1:D, D2:A.MOTOR2_LOW contains J1:P1, Q2:D, D3:A.PWM10 is H1:Pin_19 -> R1:1; Q1_GATE is R1:2 + R3:1 + Q1:G; R3:2 is GND.PWM17 is H1:Pin_11 -> R2:2; Q2_GATE is R2:1 + R4:1 + Q2:G; R4:2 is GND.GPIO24_LED is H1:Pin_18 -> J5:Pin_1; J5:Pin_2 is GND.GPIO25_LED is H1:Pin_22 -> J7:Pin_1; J7:Pin_2 is GND.J6:C is No Connect unless plug detect is intentionally implemented.U1:dVdt, U1:~FLT, and TP3 are either wired as described or intentionally marked No Connect.Ref:Pin, for example U2:SW, L2:1, C5:P2, and existing named nets are referenced as ^NetName. Ground nets can be referenced as ^GND; non-ground nets should be created or verified before referencing them by name. This follows the Flux connection syntax guidance. See the retrieved connection-syntax guidance for details.0. Cleanup before wiring
1. Barrel jack and raw 6 V rail
`VIN_6V`
`GND`
No connect
2. TPS56339 buck converter U2
Buck input
Switch node `SW`
Bootstrap network with R9
Buck output `BUCK_5V`
Feedback `FB`
3. Buck output to Raspberry Pi through fuse/eFuse
`BUCK_5V` to fuse
eFuse input `U1_IN`
eFuse output `PI_5V`
eFuse ILM
eFuse dVdt and FLT options
4. Motor channel 1 low-side switch
Motor power
Low-side switch node `MOTOR1_LOW`
MOSFET source
Flyback diode orientation
Gate drive
5. Motor channel 2 low-side switch
Motor power
Low-side switch node `MOTOR2_LOW`
MOSFET source
Flyback diode orientation
Gate drive
6. LED GPIO JST connectors
GPIO24 LED connector
GPIO25 LED connector
7. Test point TP3
8. Final ERC checklist
Notes on connection syntax