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help me create the antenna for the nrf52840
jakobabs

jakobabs

@copilot help me create the antenna for the nrf52840
1y

copilot

The nRF52840 is a versatile SoC from Nordic Semiconductor that includes a built-in RF transceiver supporting various wireless protocols. In designing the antenna for the nRF52840, you need to follow careful layout and design principles to ensure optimal RF performance.
Key Steps to Design the Antenna for the nRF52840:
  1. Select the Antenna Type: The most common types for this frequency are PCB trace antennas like meandered or inverted-F antennas (IFA), chip antennas, or external antennas.
  2. Place the Antenna Properly: Position the antenna at the edge of the PCB, away from noisy components.
  3. Impedance Matching: Ensure the antenna is impedance-matched to 50 Ω to maximize power transfer and minimize reflection.
  4. RF Layout Guidelines: Follow Nordic’s PCB layout guidelines for the RF section, such as grounding, shielding, and trace width.
Steps for a Meandered Inverted-F Antenna (MIFA)
  1. Antenna Layout:
    • Create a meandered line on the PCB with a length that achieves resonance at approximately 2.4 GHz.
    • Start with a trace width of around 1 mm and a length adjusted to fit the space available.
  2. Ground Plane:
    • Ensure there is a continuous ground plane under the RF section, but keep it away from the antenna area itself.
  3. Matching Network:
    • Include a matching network with SMT components like capacitors and inductors to fine-tune the impedance. Use the network connected to the antenna feedpoint.
  4. Testing and Tuning:
    • Use a vector network analyzer to measure the impedance and adjust the matching network as necessary.
Sample Schematic Connections:
Connect the antenna to the nRF52840 as follows:
  • Antenna Feedpoint: Connect to U1:ANTU1:ANT.
  • Matching Network: This typically includes components like an inductor (L1) and two capacitors (C16 and C17).
Example connections:
  • Connect U1:ANTU1:ANT to matching network components.
  • Connect matching network output to the antenna feedpoint.
Example Layout:
  1. Antenna Design:
    • Start from the U1:ANTU1:ANT pin and draw the antenna trace.
  2. Ground Plane Clearance:
    • Keep a clearance of around 2-3 mm around the antenna’s trace.
Adding Parts to Your Schematic:
You can use the built-in components in Flux:
  • Matching Network Components: Choose appropriate 0402 or 0603 capacitors and inductors.
  • PCB Antenna: Design the trace to match your antenna specifications directly on the PCB layout tool in Flux.
Example Values for a Matching Network:
  • L1L1: 3.9 nH
  • C16C16: 0.5 pF
  • C17C17: 1.0 pF
Would you like to proceed with a specific antenna type, or do you need further details on the matching network components and layout? Let me know, and I can provide more tailored guidance!
1y
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Note: IC2 the PAT9130 trackball sensor from PixArt. Since the datasheet is confi...
jakobabs

jakobabs

Note: IC2 the PAT9130 trackball sensor from PixArt. Since the datasheet is confidential, the information shown here is in compliance with the NDA I signed. No further information regarding the PAT9130 will be given.
1y
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C5 -> W1 C6 -> AD23 C7 -> A22 C8 -> AD14 C9 -> B1
jakobabs

jakobabs

C5 -> W1 C6 -> AD23 C7 -> A22 C8 -> AD14 C9 -> B1
1y
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what capacitance should I use for this oscillator?
jakobabs

jakobabs

@copilot what capacitance should I use for this oscillator?
1y

copilot

To determine the appropriate capacitance values for your oscillator circuit with the ABS07-32.768KHZ-T crystal, you typically need to refer to the crystal's datasheet. The common load capacitance for 32.768 kHz crystals is usually between 9 pF to 12.5 pF.
However, based on common practices, you might start with 12 pF for the capacitors ($C13$ and $C12$) if the specific datasheet is not available.
Here is a typical configuration to connect your oscillator:
Connections:
  • Connect $X1$:P1 to $U1$:XL1/P0.00.
  • Connect $X1$:P2 to $U1$:XL2/P0.01.
  • Connect $X1$:P1 to $C13$:P2.
  • Connect $X1$:P2 to $C12$:P2.
  • Connect $C13$:P1 to GND.
  • Connect $C12$:P1 to GND.
This should give you a stable 32.768 kHz oscillation for your NRF52840-QIAA-R microcontroller. If you have the specific datasheet for your crystal, I would recommend confirming the exact load capacitance values.
1y
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TFT_TC
TFT_CC
TFT_RT
GPIO5
TFT_BL
TFT_SI
GPIO5
PAT_5
TFT_TC
TFT_RT
TFT_SO
GPIO3
TFT_CC
GPIO2
PAT_9
TFT_SO
PAT_8
GPIO2
TFT_SI
TFT_CK
GPIO1
TFT_DC
TFT_BL
GPIO6
GPIO3
3V3
PAT_7
GPIO4
TFT_CK
GPIO1
GPIO6
3V3
PAT_10
TFT_DC
J4
J3
J5
R7
Resistance
3.3kΩ
C15
Capacitance
12pF

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Design Challenge - Jacob Kelly

Design Challenge - Jacob Kelly thumbnail
NRF52840 evaluation board with a battery charger (BQ24072), display(Adafruit 1.47" 172x320 ST7789), and a trackball sensor (PAT9130)

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