Custom PCB Design for Thesis

flux

1:16

Clarifying datasheet usage.

Gathering datasheet and schematic.

Analyzing the schematic.

Looking for "RC-SM1276-868 pinout and host MCU interface pins: SPI pins, NSS/CS, SCK, MOSI, MISO, RESET, DIO0-DIO5, power pins, ground pins, antenna pin" in info-rf%20rc-sm1276-868.pdf

Looking for "Recommended application circuit and required external components for RC-SM1276-868: supply decoupling capacitors, reset network, RF matching, crystal or oscillator requirements, antenna connection, pull-ups or pull-downs" in info-rf%20rc-sm1276-868.pdf

Looking for "Electrical and layout recommendations for RC-SM1276-868 relevant to connecting an ESP32: supply voltage, decoupling placement, digital IO voltage levels, antenna and grounding guidance" in info-rf%20rc-sm1276-868.pdf

Specifying required connections.

Identifying available GPIOs.

For the RC-SM1276-868, the exact pin mapping should come from its datasheet rather than memory, especially for module pins and support circuitry
Required ESP32-to-LoRa connections
Your existing U1 pin choices already line up well with the SPI-style interface you’d want for the RC-SM1276-868.

Recommended mapping

RC-SM1276-868 padFunctionConnect to ESP32In your current project
2VDD (1.8 V to 3.7 V)3.3 V railsame rail as U1
3, 4GNDGroundsame GND as U1
12SCKSPI clockU1 IO18
13MISOSPI MISOU1 IO19
14MOSISPI MOSIU1 IO23
15NSSSPI chip selectU1 IO5
5NRESETReset controlU1 IO16
6DIO0Interrupt/statusU1 IO26
7DIO1Interrupt/statusU1 IO27
Additional module pins you should plan for
The datasheet also exposes these pins on the RC-SM1276-868:

Table

PadSignalWhat to do
8DIO2 / DataRoute to a spare GPIO if your firmware/library needs it
9DIO3Optional spare GPIO connection
10DIO4Optional spare GPIO connection
11DIO5Optional spare GPIO connection
1TX_ENRF switch control, follow module reference usage
16RXTX / RF_MODRF switch control, follow module reference usage
18RX_ENRF switch control, follow module reference usage
17NCLeave unconnected
Required support parts
From the module datasheet, these are the support items I’d treat as required or directly reference-backed:
1) Supply decoupling
The reference schematic shows one capacitor from VDD to GND, labeled C1 = “106”, placed directly at the module supply pin. The safe implementation is a local decoupling capacitor placed very close to the module power pin. The general decoupling pattern of 100 nF + bulk capacitance is also a good project-level practice for IC rails
Suggested parts:
2) RF switch control network
The datasheet shows an external resistor network associated with the RF switch control connection:
  • 100 k
  • 10 k
  • 2.2 k
  • 1 k
So if you use the module exactly as intended, include these with:
3) No external crystal required
The block diagram shows an internal 32 MHz crystal, so you do not need to add an external crystal for the RC-SM1276-868.
4) No external RF matching network called out
The datasheet indicates the RF switch and RF matching are inside the module, so I would not add a separate external matching network unless you have a more detailed RF reference from the vendor.
Antenna note
The datasheet indicates the antenna connection is provided by the module RF path and references a uA connector plus optional helical antenna. That suggests the antenna-side implementation is module-defined, but I would still verify the exact footprint/connector style before locking the PCB.
Practical recommendation for your design
For your U1, I’d wire the RC-SM1276-868 like this:
  • Keep your current SPI lines:
    • IO18 -> SCK
    • IO19 -> MISO
    • IO23 -> MOSI
    • IO5 -> NSS
  • Keep:
    • IO16 -> NRESET
    • IO26 -> DIO0
    • IO27 -> DIO1
  • Add:
What’s still uncertain
The only part I would still verify before schematic capture is the exact handling of:
  • TX_EN
  • RX_EN
  • RXTX/RF_MOD
  • the exact antenna connector footprint/orientation
If you want, I can next make a pin-by-pin replacement map from your current U2 to RC-SM1276-868, so you can see exactly what changes in the schematic.
Make replacement map
Show RF control
Find decoupling values
Add optional DIOs
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U1 EN - R2 P2
IC1 VDD_I/O - C5 P1
U1 EN - R2 P2
U4 VDDIO - C4 P1
U1 EN - R2 P2
U1 IO22 - U4 SCK
U1 EN - R2 P2
IC1 VDD_I/O - C5 P1
U1 EN - R2 P2
U1 EN - R2 P2
U1 EN - R2 P2
U3 VCC_RF - C3 P1
U1 EN - R2 P2
U1 IO21 - U4 SDI
GND
R5
Resistance
4.7kΩ
C2
Capacitance
100nF
U4 GND - C4 P2
R3
Resistance
10kΩ
C1
Capacitance
100nF
C3
Capacitance
100nF
U3 GND - C3 P2
C4
Capacitance
100nF
R4
Resistance
4.7kΩ
R2
Resistance
10kΩ
R1
Resistance
10kΩ
U2 GND@2 - C2 P2
  • Ground
    Ground
    A common return path for electric current. Commonly known as ground.
    jharwinbarrozo
    20.5M
  • Net Portal
    Net Portal
    Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
    jharwinbarrozo
    43.0M
  • Power Net Portal
    Power Net Portal
    Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
    jharwinbarrozo
    11.4M
  • Generic Resistor
    Generic Resistor
    A generic fixed resistor ideal for rapid circuit topology development. Its footprint automatically adapts based on the selected package case code—supporting 0402, 0603, 0805, 1203, and many other standard SMD packages, as well as axial horizontal and vertical configurations. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0 ohm, 10 ohm, 100 ohm, 1.0k ohm, 10k ohm, 100k ohm, 1.0M ohm 1.1 ohm, 11 ohm, 110 ohm, 1.1k ohm, 11k ohm, 110k ohm, 1.1M ohm 1.2 ohm, 12 ohm, 120 ohm, 1.2k ohm, 12k ohm, 120k ohm, 1.2M ohm 1.3 ohm, 13 ohm, 130 ohm, 1.3k ohm, 13k ohm, 130k ohm, 1.3M ohm 1.5 ohm, 15 ohm, 150 ohm, 1.5k ohm, 15k ohm, 150k ohm, 1.5M ohm 1.6 ohm, 16 ohm, 160 ohm, 1.6k ohm, 16k ohm, 160k ohm, 1.6M ohm 1.8 ohm, 18 ohm, 180 ohm, 1.8K ohm, 18k ohm, 180k ohm, 1.8M ohm 2.0 ohm, 20 ohm, 200 ohm, 2.0k ohm, 20k ohm, 200k ohm, 2.0M ohm 2.2 ohm, 22 ohm, 220 ohm, 2.2k ohm, 22k ohm, 220k ohm, 2.2M ohm 2.4 ohm, 24 ohm, 240 ohm, 2.4k ohm, 24k ohm, 240k ohm, 2.4M ohm 2.7 ohm, 27 ohm, 270 ohm, 2.7k ohm, 27k ohm, 270k ohm, 2.7M ohm 3.0 ohm, 30 ohm, 300 ohm, 3.0K ohm, 30K ohm, 300K ohm, 3.0M ohm 3.3 ohm, 33 ohm, 330 ohm, 3.3k ohm, 33k ohm, 330k ohm, 3.3M ohm 3.6 ohm, 36 ohm, 360 ohm, 3.6k ohm, 36k ohm, 360k ohm, 3.6M ohm 3.9 ohm, 39 ohm, 390 ohm, 3.9k ohm, 39k ohm, 390k ohm, 3.9M ohm 4.3 ohm, 43 ohm, 430 ohm, 4.3k ohm, 43K ohm, 430K ohm, 4.3M ohm 4.7 ohm, 47 ohm, 470 ohm, 4.7k ohm, 47k ohm, 470k ohm, 4.7M ohm 5.1 ohm, 51 ohm, 510 ohm, 5.1k ohm, 51k ohm, 510k ohm, 5.1M ohm 5.6 ohm, 56 ohm, 560 ohm, 5.6k ohm, 56k ohm, 560k ohm, 5.6M ohm 6.2 ohm, 62 ohm, 620 ohm, 6.2k ohm, 62K ohm, 620K ohm, 6.2M ohm 6.8 ohm, 68 ohm, 680 ohm, 6.8k ohm, 68k ohm, 680k ohm, 6.8M ohm 7.5 ohm, 75 ohm, 750 ohm, 7.5k ohm, 75k ohm, 750k ohm, 7.5M ohm 8.2 ohm, 82 ohm, 820 ohm, 8.2k ohm, 82k ohm, 820k ohm, 8.2M ohm 9.1 ohm, 91 ohm, 910 ohm, 9.1k ohm, 91k ohm, 910k ohm, 9.1M ohm #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Capacitor
    Generic Capacitor
    A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF, 10pF, 100pF, 1000pF, 0.01uF, 0.1uF, 1.0uF, 10uF, 100uF, 1000uF, 10000uF 1.1pF, 11pF, 110pF, 1100pF 1.2pF, 12pF, 120pF, 1200pF 1.3pF, 13pF, 130pF, 1300pF 1.5pF, 15pF, 150pF, 1500pF, 0.015uF, 0.15uF, 1.5uF, 15uF, 150uF, 1500uF 1.6pF, 16pF, 160pF, 1600pF 1.8pF, 18pF, 180pF, 1800pF 2.0pF, 20pF, 200pF, 2000pF 2.2pF, 22pF, 220pF, 2200pF, 0.022uF, 0.22uF, 2.2uF, 22uF, 220uF, 2200uF 2.4pF, 24pF, 240pF, 2400pF 2.7pF, 27pF, 270pF, 2700pF 3.0pF, 30pF, 300pF, 3000pF 3.3pF, 33pF, 330pF, 3300pF, 0.033uF, 0.33uF, 3.3uF, 33uF, 330uF, 3300uF 3.6pF, 36pF, 360pF, 3600pF 3.9pF, 39pF, 390pF, 3900pF 4.3pF, 43pF, 430pF, 4300pF 4.7pF, 47pF, 470pF, 4700pF, 0.047uF, 0.47uF, 4.7uF, 47uF, 470uF, 4700uF 5.1pF, 51pF, 510pF, 5100pF 5.6pF, 56pF, 560pF, 5600pF 6.2pF, 62pF, 620pF, 6200pF 6.8pF, 68pF, 680pF, 6800pF, 0.068uF, 0.68uF, 6.8uF, 68uF, 680uF, 6800uF 7.5pF, 75pF, 750pF, 7500pF 8.2pF, 82pF, 820pF, 8200pF 9.1pF, 91pF, 910pF, 9100pF #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Inductor
    Generic Inductor
    A generic fixed inductor suitable for rapid circuit topology development. The footprint automatically adapts based on the selected package, supporting standard SMD sizes (e.g., 0402, 0603, 0805) as well as well-known inductor packages such as SDR1806, PA4320, SRN6028, and SRR1260. Standard inductor values: 1.0 nH, 10 nH, 100 nH, 1.0 µH, 10 µH, 100 µH, 1.0 mH 1.2 nH, 12 nH, 120 nH, 1.2 µH, 12 µH, 120 µH, 1.2 mH 1.5 nH, 15 nH, 150 nH, 1.5 µH, 15 µH, 150 µH, 1.5 mH 1.8 nH, 18 nH, 180 nH, 1.8 µH, 18 µH, 180 µH, 1.8 mH 2.2 nH, 22 nH, 220 nH, 2.2 µH, 22 µH, 220 µH, 2.2 mH 2.7 nH, 27 nH, 270 nH, 2.7 µH, 27 µH, 270 µH, 2.7 mH 3.3 nH, 33 nH, 330 nH, 3.3 µH, 33 µH, 330 µH, 3.3 mH 3.9 nH, 39 nH, 390 nH, 3.9 µH, 39 µH, 390 µH, 3.9 mH 4.7 nH, 47 nH, 470 nH, 4.7 µH, 47 µH, 470 µH, 4.7 mH 5.6 nH, 56 nH, 560 nH, 5.6 µH, 56 µH, 560 µH, 5.6 mH 6.8 nH, 68 nH, 680 nH, 6.8 µH, 68 µH, 680 µH, 6.8 mH 8.2 nH, 82 nH, 820 nH, 8.2 µH, 82 µH, 820 µH, 8.2 mH #generics #CommonPartsLibrary
    jharwinbarrozo
    15.8k
  • Terminal
    Terminal
    An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
    natarius
  • RMCF0805JT47K0
    RMCF0805JT47K0
    47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
    jharwinbarrozo
    1.2M
  • 875105359001
    875105359001
    10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
    jharwinbarrozo
    1.2M
  • CTL1206FYW1T
    CTL1206FYW1T
    Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
    jharwinbarrozo
    1.1M
ESP32 LoRa Sailplane Tracker thumbnail
Custom PCB for a master's thesis automatic sailplane time-tracking device using an ESP32 with LoRaWAN, GPS6MV2 GPS, RDM6300 RFID reader, BMP280 barometer, ADXL345 accelerometer, and microSD logging. The design targets reliable sensing, onboard event logging, and wireless data transfer in a sailplane environment.

Properties

Diagram



  
    
  
  
    
  














UART

UART

SPI

SPI

I2C








Power Input node_5V
3.3V Regulator
ESP32 Module
LoRa Module
GPS Module
I2C Sensors BMP280 and ADXL345
microSD Interface
RFID Reader node_5V

Pricing & Availability

Distributor

Qty 1

Arrow

$14.72–$17.10

Digi-Key

$10.11–$102.58

LCSC

$52.85–$53.04

Mouser

$33.00–$39.97

TME

$1.12

Verical

$4.53–$8.27

Controls