From: Bdale Garbee <bdale@gag.com>
Date: Wed, 21 Oct 2020 04:52:03 +0000 (-0600)
Subject: capture more thoughts about daughter cards, etc
X-Git-Tag: fab-old-v4~5
X-Git-Url: https://git.gag.com/?a=commitdiff_plain;h=205bb99bd13037d198bf9a39f79cad8955e32173;p=hw%2Fquantimotor

capture more thoughts about daughter cards, etc
---

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.