SimpleRick PCB v1.1
See BOM spreadsheet listing all components to be soldered to the board.
- STEMiNC SMD07T05R412WL piezo
- Teensy 3.2
- micro USB cable
- header pins
- jumper wires, M-F
- XL6009 Boost Converter module
- SG90 micro servo motor
- SMA cables
- 12.5 MHz low pass filter
- RTL-SDR v3
- computer with USB ports
Setup for debugging
- SMA splitter
- SMA to BNC adapter
- BNC cables
- oscilloscope with probes
- Use stencil to apply solder paste.
- Pick and place SMD components.
- Manually solder through hole components.
- (optional) Solder test points to pads on back.
- Solder header pins to Teensy, then attach it to header pins on SimpleRick.
- Solder jumper wires to boost converter, then attach it to header pins on SimpleRick.
- Solder female SMA connector to piezo, then connect it to SimpleRick with SMA cable.
- Attach piezo to servo motor however you like. I used hot glue.
- Flash SimpleRick firmware to Teensy.
- Connect RTL-SDR and low pass filter with SMA cables.
- Follow instructions for using rtl-ultrasound software.
Fix errata in PCB layout:
- swapped labels for V_PIEZO and GND testpoints
- LED_ACQUISITION should say LED_PWR
- some silkscreen labels are cutoff by vias
- GND testpoint for V_GAIN is inconveniently placed too close to V_GAIN testpoint
Other things to be improved:
- high current traces should be wider
- add bleeder resistor between V_PIEZO and GND
- insufficient decoupling for servo motor
- separate AGND and DGND planes
- reduce usage of high value MLCC due to supply shortage
- use larger components for VUSB filter
- get premade connectors for attaching Teensy
- LEDs for: 5V, 3.3V, acquisition
- servo power rail needs more decoupling
- make silkscreen info (author, license, version, etc) more readable... consider moving it to back