- add another 2-pin header to PA8 (MCO) so we can sample the master clock to
calibrate the SOC oscillator, which means moving the RED RF strength LED to
some other gpio line
+
+2019.10.31
+- The more I think about this project, the more I want to go back to a board
+ that just does one each load cell and pressure sensor. I just haven't ever
+ actually used anything else.
+
+ Discussion with Joe Bowen made it clear that if I were to design such a
+ board so that it could take option cards, and/or had just a pile of basic
+ analog inputs and maybe switch outputs available, that doing other stuff
+ could be fun, and we'd "grow the system as we need to". Every time I tried
+ to pin him down on specs, all I got was vagueness.
+
+2020.01.18
+- Maybe the right answer is to move to the ADS131A02 which is the 2-channel
+ version of the acquisition chip, and costs less. That would support one
+ pressure sensor and one load cell. Then make it possible to add on other
+ acquisition boards somehow.
+
+2020.10.20
+- sticking with the ADS131A04 and routing the extra two inputs to the header
+ means that supporting 2 burn wires for the strand burner daughter card is
+ dead simple. it also means that adding a second load cell and pressure
+ sensor if required on a daughter card would also be dead simple.
+
+- for strand burner, I need a daughter card that provides a high-side switch
+ for pyro power (since I need a common ground through the system), and has
+ resistors for 2 ADC inputs hooked to burn wires. Bring this all out through
+ a 5-pin connector to the outside that hooks to the strand burner end. We'd
+ also use the existing pressure sensor channel, but not use the load cell.
+
+ So, firmware wants to log all 4 analog inputs all the time. For a test
+ stand run, only the pressure sensor and load cell are relevant. For strand
+ burner, pressure sensor and the two burn wires are relevant.
+
+- for Jamie / Estes, I need a daughter card that adds at least 4 thermistor
+ inputs, and support for their Sony camera trigger thing.
+
+- 40 pin header and mating female connector for daughter cards w/q1 pricing
+
+ header Sullins PRPC020DAAN-RC DK S2011EC-20-ND 0.90
+ mating Sullins PPPC202LFBN-RC DK S7123-ND 2.38
+
+- high-side switch for strand burner daughter card. This is an 8-SO part
+ good to 28V and 21A, 50 mOhm on resistance. Should be trivial to make
+ work on a 2-layer PCB
+
+ ST's VN7050ASTR, DK 497-15993-1-ND, 1.58
+
+ Means we need multiple header pins carrying pyro voltage to get enough
+ current, since the header spec is 3A per pin. 2-4 pins each for v_pyro
+ on the pin 1 end, and gnd on the other end should do.
+
+- for strand burner daughter, use CUI TB003-500-P06BE 6-position 5mm pitch
+ screw terminal strip, supports 14-26 AWG wire, 10A per pin continuous,
+ DK 102-6165-ND, $1.01 q1
+
projects / hw / quantimotor / blobdiff