The sensor board contains a 4 channel A/D converter. This reads the current voltage of the two batteries and the pressure and acceleration values.
These can be used for staging, deployment, logging or any other use you need.
You don't have to populate this board. That is if you only need a staging controller you don't need to put the pressure sensor on the board. Or if you only want a descent rate altimeter then you only need the pressure sensor.
I added a low pass filter to the output of the Accelerometer with the
suggestion of David Schultz. I had designed one for a different design called my
advanced altimeter that I never built so I used that one. It had a 10Hz roll off
since I will be sampling at 25Hz. To standardize parts I went with a .1uF cap
instead of the .15uF. This sets it at 15Hz. The Op amp was chosen because it is
a low power rail-to-rail that's in a tiny package.
The gain is set to 1 so
you get the full +-50G range. This can be adjusted by component selection for
the opamp. If you think a different range would be better let me know. I'm not
quite sure if 50G is overkill or not.
Trace Patterns
Detailed parts list
| Sensor board | ||||||
| Supplier Part Number | Manufacturer Part Number | Price | Qty | Total | Supplier | Description |
| MCP3204-CI/SL-ND | MCP3204-CI/SL | $3.95 | 1 | $3.95 | Digi-Key | ADC 12BIT 4 CHANNEL 14SOIC |
| 48F6598 | MPXA4115A6T1 | $19.82 | 1 | $19.82 | Newark | Pressure sensor |
| 83F4883 | ADXL150JQC | $26.11 | 1 | $26.11 | Newark | Acceleration sensor |
| 07B5734 | LMC7101BIM5 | $0.91 | 1 | $0.91 | Newark | Low Power Rail-to Rail Op Amp |
| 263-100K | XICON | $0.08 | 2 | $0.16 | Mouser | 1206 SMD 100k resistor |
| 263-47K | XICON | $0.08 | 2 | $0.16 | Mouser | 1206 SMD 47k resistor |
| 263-1K | XICON | $0.08 | 1 | $0.08 | Mouser | 1206 SMD 1k resistor |
| 263-750 | XICON | $0.08 | 1 | $0.08 | Mouser | 1206 SMD 750ohm resistor |
| 77-VJ12V16V105Z | VJ1206V105ZXJMT | $0.33 | 1 | $0.33 | Mouser | 1206 SMD 1.0uF capacitor |
| 80-C0805C334K4R | C0805C334K4RACTU | $0.81 | 1 | $0.81 | Mouser | 0805 SMD .33uF capacitor |
| 140-CC501B104K | XICON | $0.14 | 3 | $0.42 | Mouser | 0805 SMD .1uF capacitor |
| 140-CC501B103K | XICON | $0.072 | 1 | $0.07 | Mouser | 0805 SMD .01uF capacitor |
| H2045-ND | DF11-16DS-2V(20) | $1.68 | 1 | $1.68 | Digi-Key | Surface Mount Vertical Socket |
| H2078-ND | DF11-16DP-2V(20) | $1.62 | 1 | $1.62 | Digi-Key | Surface Mount Protected Header |
| Total Cost | $56.64 | |||||
The pressure sensor price goes down rapidly when bought in quantity its $16.02 each for 10.
The accelerometer price goes down rapidly when bought in quantity its $23.51 each for 10, $18.28 each for 100.
