X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=Notebook;h=ab111a417377d4b9b71b0b6bd13b307e8112c89e;hb=0d26cee85dab6687e6e88a5266b5423245b28659;hp=8a0457c85933af76bd4966952b2d3d8dba922686;hpb=b82c2f79aa0e2fc17cd0d0a692459c206463b92b;p=hw%2Ftelemetrum

diff --git a/Notebook b/Notebook
index 8a0457c..ab111a4 100644
--- a/Notebook
+++ b/Notebook
@@ -67,10 +67,79 @@
 - can I put the GPS chip antenna on the board *and* allow for an SMA or other
   connector if we want it off-board?
 
+- changing the memory part from the SOIJ8 to the DFN8 would save about 2mm
+  in width, but that doesn't really help.
+- changing the 5V switcher from S8 to MS8 takes us from 5 tall to 3 tall, but
+  costs $0.30 more per piece and isn't stocked by Digikey.  Not worth it?
+
+- noticed the NXP SC18IS600, which is an SPI slave to I2C master interface
+  with a few GPIO lines...  mate that with an HMC5843, which is a 3-axis
+  magnetic sensor, and we might have another interesting companion board for TM
+
+
 
 - To Do List
 
 	- add serial connector back to schematic as optionally loaded part
 	- move USB connector on PCB layout 80 mils in from board edge
-	- create PCB footprints for the GPS module and GPS antenna
+		- move yellow LED and passives closer to LiPo connector
+	+ create PCB footprint for the GPS module 
+	+ create PCB footprint for the GPS antenna
+
+
+2009.10.09
+- flew lots of stuff last weekend at O'fest.  100g accel worked ok in G-Spot,
+  broke beeper presumably on landing with tangled chute.  board seems ok
+  otherwise, need to verify that baro sensor is still ok.
+
+- put out sample requests for gps passive patches from 3 vendors
+
+- when adding GPS, let's plan for passive patch loaded on the back of the 
+  board, plus a U.FL connector loaded on the top of the board with DC bias feed
+  to support external active antennas.  This probably means passive patch
+  direct to gps chip, then a dc blocking cap, a chip inductor for dc bias
+  injection, and the connector.  A suitable connector is:
+
+	WM5587CT-ND	Molex 73412-0110	0.70 in single quantity
+
+  Keith found gps active antennas with cable to U.FL connectors and Molex sells
+  cables with U.FL to bare leads, so this should cover the bases.
+
+- TelePyro doesn't need a CPU.  How about an SPI to I2C converter chip with
+  GPIO lines and an I2C ADC chip?
+
+  The Silabs CP2120 has 8 gpio lines but is only available in QFN20.  The NXP
+  part I discovered earlier, the SC18IS600, has 4 full gpio lines and 2 lame-o
+  pins, but is available in a hand-solderable version.  Add in a Maxim ADC, 
+  and something like this emerges:
+
+	DigiKey	568-3232-5-ND	NXP SC18IS600IPW,112	2.25
+	DigiKey	MAX11603EEE+-ND	Maxim MAX11603EEE+	4.00
+	Mouser	595-CD4508BM	TI CD4508BM		1.70
+
+  The 4508 has separate reset inputs and latch controls for each 4-bit latch.
+  The reset forces all outputs low, and the reset is an active-high input.
+
+  The NXP part has an active-low reset input, with 10-30k internal pullup.
+
+  The ADC has no distinct reset input.
+
+  A suitable SOT-23-5 reset controller is the MCP1319MT-29LE... it has a master
+  reset input we can ignore, and both active high and active low reset outputs.
+
+	DigiKey	MCP1319MT-29LE/OTCT-ND			0.70
+
+  This plus 8 copies of the pyro circuit on TM (FET and 4 resistors) and we're
+  good to go.  
+
+  Wonder if there are resistor networks it'd be worth trying to use to ease 
+  component placement?  Yes... these are 8 x 0402, more or less:
+
+	100 ohm		741X163101JPCT-ND		0.16
+	10k		741X163103JPCT-ND		0.16
+	27k		Y1273CT-ND			0.18
+	100k		Y1104CT-ND			0.18
 
+- another way to think about all this is that I could panelize a set of boards
+  all done in 2 layers, then treat that as a sub-panel I put N copies down of
+  to fill up a 33each.com max panel size.