GPS IoT Performance Evaluation
Thought for 3 sec
flux
nets {
net 3V3 = LED1:A, R4:P1, R7:P2, U3:VCC, U2:VOUT, Rpi1:3V3;
net RUN = Rpi1:RUN, R7:P1, C9:P1;
net GND = Rpi1:23, Rpi1:28, Rpi1:33, Rpi1:38, Rpi1 GND - U3 GND:GND, C9 P2 - C10 P2:GND, C7:P2, C9:P2, R1:P2, LED1:K, U3:GND, C6:P2, C5:P2, J1 SHIELD__3 - D1 GND:GND, U1:GND, C4:P2, J1:SHIELD__3, J1:SHIELD__2, J1:SHIELD__1, J1:SHIELD, J1:GND__1, J1:GND, GND:GND, Rpi1 GND - Rpi1 GND:GND, J2:PIN2, C1:P2, U2:GND, Rpi1:18, Rpi1:13, Rpi1:8, Rpi1:3, C2:P2, C8:P2, C3:P2, R2:P2, C10:P2;
net VBUS = C2:P1, C6:P1, J1:V-BUS, J1:V-BUS__1, Rpi1:VBUS, C3:P1, C1:P1, U1:IN;
net GPS_RX = Rpi1:GP1, U3:TX;
net CHG_VDD = C8:P1, U1:NTC, R6:P2, U1:VDD, R5:P2;
net GPS_TX = Rpi1:GP0, U3:RX;
net CHG_SDA = R5:P1, U1:SDA;
net ADC_VREF = Rpi1:ADC_VREF, C10:P1;
net SYS = U2:VIN, U2:EN, C4:P1, Rpi1:VSYS, U1:SYS, C7:P1;
net CC1 = J1:CC1, R1:P1;
net VBAT = C5:P1, U1:BATT, J2:PIN1;
net CHG_STAT = R3:P1, U1:INT;
net CC2 = R2:P1, J1:CC2;
net CHG_SCL = R6:P1, U1:SCL;
net 3V3_LED = R4:P2, LED2:A;
net CHG_STAT_LED = LED2:K, R3:P2;
}
net 3V3 = LED1:A, R4:P1, R7:P2, U3:VCC, U2:VOUT, Rpi1:3V3;
net RUN = Rpi1:RUN, R7:P1, C9:P1;
net GND = Rpi1:23, Rpi1:28, Rpi1:33, Rpi1:38, Rpi1 GND - U3 GND:GND, C9 P2 - C10 P2:GND, C7:P2, C9:P2, R1:P2, LED1:K, U3:GND, C6:P2, C5:P2, J1 SHIELD__3 - D1 GND:GND, U1:GND, C4:P2, J1:SHIELD__3, J1:SHIELD__2, J1:SHIELD__1, J1:SHIELD, J1:GND__1, J1:GND, GND:GND, Rpi1 GND - Rpi1 GND:GND, J2:PIN2, C1:P2, U2:GND, Rpi1:18, Rpi1:13, Rpi1:8, Rpi1:3, C2:P2, C8:P2, C3:P2, R2:P2, C10:P2;
net VBUS = C2:P1, C6:P1, J1:V-BUS, J1:V-BUS__1, Rpi1:VBUS, C3:P1, C1:P1, U1:IN;
net GPS_RX = Rpi1:GP1, U3:TX;
net CHG_VDD = C8:P1, U1:NTC, R6:P2, U1:VDD, R5:P2;
net GPS_TX = Rpi1:GP0, U3:RX;
net CHG_SDA = R5:P1, U1:SDA;
net ADC_VREF = Rpi1:ADC_VREF, C10:P1;
net SYS = U2:VIN, U2:EN, C4:P1, Rpi1:VSYS, U1:SYS, C7:P1;
net CC1 = J1:CC1, R1:P1;
net VBAT = C5:P1, U1:BATT, J2:PIN1;
net CHG_STAT = R3:P1, U1:INT;
net CC2 = R2:P1, J1:CC2;
net CHG_SCL = R6:P1, U1:SCL;
net 3V3_LED = R4:P2, LED2:A;
net CHG_STAT_LED = LED2:K, R3:P2;
}
Thought
flux
Work done
- Audited the existing schematic and confirmed the critical architecture remains intact: USB-C input at J1, charger/power-path at U1, 3.3 V regulation at U2, Pico controller at Rpi1, and GPS UART module at U3.
- Cleaned up net naming for the indicator path by renaming the LED support nets to 3V3_LED and CHG_STAT_LED, while preserving the existing charger/status behavior on R3, R4, LED1, and LED2.
- Re-verified the important named nets directly from the schematic: VBUS, SYS, VBAT, 3V3, GPS_RX, GPS_TX, CHG_SDA, CHG_SCL, CHG_STAT, RUN, and ADC_VREF.
- Updated Rpi1 documentation to explicitly record that GP2-GP22 and GP26-GP28 are intentionally unused/reserved and that
3V3_ENis intentionally left open to keep the onboard regulator enabled. - Re-ran ERC and confirmed the remaining findings are limited to the intentionally unused Pico pins and Rpi1
3V3_EN; no power-pin, undriven-net, single-pin-net, or driver-conflict issues remain in the critical design paths.
Success criteria review
- ✅ Named nets are consolidated and clear, with charger, power, UART, reset, and ADC reference nets verified.
- ✅ Critical power-path connectivity is valid from J1 through U1 to U2, and the Pico/GPS UART between Rpi1 and U3 is preserved.
- ✅ The schematic is documented to be review-ready, including explicit notes about intentional unused pins on Rpi1.
- ❌ I could not place true no-connect annotations on the unused Pico pins because there is no tool in this environment for adding schematic no-connect markers directly to existing symbol pins. The remaining ERC items are therefore documented intentional warnings rather than eliminated warnings.
