From 205bb99bd13037d198bf9a39f79cad8955e32173 Mon Sep 17 00:00:00 2001 From: Bdale Garbee Date: Tue, 20 Oct 2020 22:52:03 -0600 Subject: [PATCH] capture more thoughts about daughter cards, etc --- Notebook | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/Notebook b/Notebook index 2f6fe2e..cc807cb 100644 --- a/Notebook +++ b/Notebook @@ -22,3 +22,37 @@ 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. -- 2.30.2