trescorder

Trèscorder (very corder) -- an implementation of a Tricorder.

host computer

• protocol API
  • Think functional interface - avoid state
  • Think asynchronous messages/events - avoid blocking
  • simple flat message/event byte structure for communications (think JSON).
  • Simple base-class API wraps message structures.
  • Utility classes wrap async communications to provide blocking style command/response interfaces (with timeouts).
• Robust logging of data
  • separate process/daemon to pump data to FIFO, file, memmapped, kqueue?
    • circular queue/fixed size FIFO
  • separate process to stream FIFO to separate archive logger
    • local flat file log
    • local database
    • remote data sink

Host interface

• USB (as ADC)
• Serial
• WiFi
• BlueTooth
• Ethernet

power

• base voltage from 2S LiPoly gives 7.4 VDC regulated to 5V
• monitor capability to source requested current.
• power from USB
• External DC power input
• charge LiPoly cells
  • boost converter from 5 V up to 24 volts
    • If taken only from USB current then this will take forever.
  • charge LiPoly on host so it can operate disconnected.
  • pass-through power AND charging control so host can charge batteries in modules.

Host Protocol

• user selects protocol
• default protocol should be no-brainer
• configuration should not require high-level protocol
• always fall-back to simple serial configuration protocol
• should be easy to bit bang
• should be easy to read as ASCII or hex (which? both?)
• fallback should be ASCII

client interface

• provide DMA-like mechanism for bulk import of data
  • cache streamed input data until host can catch up.
  • record to removable flash.

client modules

• AD
  • 8 bit, 12 bit, 16 bit, etc.
  • fake, RC time measure
  • R measurement
    • temperature modules fall out of this, but need their own category
• Abstract categories for sensors that are really instances of AD, but need extra options or logic to condition measurements (for example, thermocouple probes)
• amplifiers -- opamp prefilter to AD
  • differential, dual input (need ground reference?), calibrated for sensors like strain gauges.
  • differential, single input vs. internal voltage reference
  • integrating
• voltage references
• IR reflectivity user provides GND, Vcc. Vout is output. Prefilter for AD or provide onboard RC time measure?
• Ethernet
• CAN
• I2C
• Serial TTL
• Serial True RS-232
• counters
  • integrating counter
  • counter with precision time base (frequency counter)
• Pressure
• Ph
• audio
• magnetic compass
• voltage
• current
• digital logic (5v, 3.3v, 2v, etc. autorange)
• digital signal generator
• analog signal generator