From 168fc1c7cf9ea0a4a7fb2144a21d1d63be0f4181 Mon Sep 17 00:00:00 2001 From: Bdale Garbee Date: Sat, 10 Oct 2009 07:57:29 -0600 Subject: [PATCH] pondering TP guts and such in Notebook file --- Notebook | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/Notebook b/Notebook index 6565442..ab111a4 100644 --- a/Notebook +++ b/Notebook @@ -86,3 +86,60 @@ + 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. -- 2.30.2