Shield Assembly - DeeEmm/DIY-Flow-Bench GitHub Wiki
Overview
The DIYFB official shield comprises of the DIYFB shield PCB and the following basic components
| Component | Part No. | Manufacturer | Details |
|---|---|---|---|
| Buck PSU | LM2596S | Generic | 3.3v Bus |
| Buck PSU | LM2596S | Generic | 5v Bus |
| Level Converter | PCA9306 | SPARKFUN | I2C level converter |
| ADC | ADS1115 | Adafruit | 16 bit analog ADC |
| Stepper drivers | DRV8825 | Pololu | Bleed / Valve control |
| Pressure Sensors | See Wiki | Various | pRef / pDiff / Pitot |
| Darlington Array | ULN2003A | Various | 12v Output switching |
The full component listing can be viewed in the interactive BOM
In addition to the above listed components are the Wemos D1 ESP32 MCU and the pressure sensors.
Pressure sensor selection will largely depend on cost and availability. The recommended sensors are listed below
| Component | Part No. | Manufacturer | Details |
|---|---|---|---|
| MPXV7007DP | MPXV7007DP | NXP | +/- 7kPa differential |
| XGZP6899A | XGZP6899A | CFSensor | +/- 7kPa differential |
Other sensors can be used, but increased range will reduce resolution and cause instability in readings
Component installation
All components are through-hole style solder type components. All BOB components should be attached to the PCB using pin sockets on the PCB and pins on the BOBs
For ease of assembly, we recommend that you assemble the PCB in the following order:
- Resistors
- Capacitors
- Fuse Holder
- PSU socket (can recycle socket from ESP32)
- Pin headers / sockets
- ULN2003
- PSU Bucks
- Wiring / Molex connectors
It should be noted that the ESP32 mounts to the underside of the board and all other BOBs mount to the top.
If using the SD Card, there are options to mount the SD card BOB to either the top or the bottom of the board, depending on which pressure sensors are used. The SD card should mount to the opposite side to the pressure sensors. The pressure sensor mount as follows
| Sensor | Mounting location |
|---|---|
| MPXV7007DP | Top |
| XGZP6899A | Bottom |
| MPX4250AP | Top |
Field connections
The edge connector is designed to use molex style sockets. These are commonly referred to as HDD connectors and are widely available in various lengths. You can also solder the wiring loom directly to the PCB. Either method is fine.
PCB case
The PCB is designed to fit in a standard 100mm Hammond enclosure.