X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=Notebook;h=9ecebc916095b60504e6760618a1ac66c2c71fb9;hb=132a04fbf9b509ae3781f7b7c37372a5d7812b25;hp=8a0457c85933af76bd4966952b2d3d8dba922686;hpb=b82c2f79aa0e2fc17cd0d0a692459c206463b92b;p=hw%2Ftelemetrum diff --git a/Notebook b/Notebook index 8a0457c..9ecebc9 100644 --- a/Notebook +++ b/Notebook @@ -67,10 +67,151 @@ - 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 really need a CPU. How about an SPI to I2C converter chip + with GPIO lines and an I2C ADC chip? Cheaper and easier than a PIC? + + PIC16F882 in SSOP-28 is $2.10 per, 1.41 @ 25 units + -- PIC16F883 is $2.12, PIC16F886 is $2.32, have better memories + CP2120 in QFN-20 is $2.41 per, 2.27 @ 25 units + + 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. + +2009.10.16 +- move to AT45DB161D 16-megabit SPI "DataFlash" EEPROM from Atmel? + AT45DB161D-SU-ND in SOIC-8 for $2.26 each + appears to compare favorably against $4.40 for current 128kx8 part + minor concern about write power, but probably red herring + +2010.02.08 +- looking at LiPo charger alternatives + + MAX8808 DFN8, not carried by DK + MAX8814 DFN8, not carried by DK + + LTC4095 DFN8, LTC4095EDC#TRMPBFCT-ND 2.91 2.34@100 + 950mA, resistor current set, rate limit input, suspend input, + NTC thermal control option, smart CHRG led with 4 states + LTC4065 DFN6, LTC4065EDC#TRMPBFCT-ND 2.77 2.23@100 + 750mA, resistor current set, CHRG led, enable input + LTC4065A DFN6, LTC4065AEDC#TRMPBFCT-ND 2.77 2.23@100 + 750mA, resistor current set, CHRG led, supply present out + + MCP73811 SOT23-5, MCP73811T-420I/OTCT-ND 0.63@1 0.39@100 + input selects 85 vs 450mA charge current + + MCP73837 DFN10, MCP73837T-FCI/MFCT-ND 1.37@1 0.85@100 + usb rate select, power good output, dual inputs, dual status + + LX2206 DFN10, LX2206CT-ND 2.68@1 2.01@100 + rate select, power good output... needs more passives? + + LM3658 DFN10, + dual input, dual rate, two status outputs .. not obvious win + + MCP73855 DFN10, MCP73855T-I/MFCT-ND 1.85@1 1.18@100 + see Microchip app note 971 + + + Talking to Keith, there's no reason we couldn't use an 8-pin PIC to augment + a standalone LiPo charger, implementing a timer after vusb application + before switching the regulator to high current, to allow the cc1111 time to + finish the USB bus negotiation phase. We could also monitor various state + bits and multiplex signaling onto one LED. A combo like the MCP73837 plus + a PIC10F206 or 220 would net under $1.50 at 100 pieces and be pretty + powerful. Since the PIC has avilable weak pull-ups on the gpio lines, the + open-drain state outputs from the regulator don't need resistors to be read. + +2011.01.17 +- v1.0 and v1.1 boards have a minor error in that the v_lipo sampling resistors + are on "the wrong side of the cut" if you try to use a separate pyro battery. + The workaround is to cut that trace and put in a jumper, which pretty much + requires "return to Bdale for rework". We should fix this for a future PCB + revision. + +2011.09.12 +- chatted with Adrian some yesterday. He likes a Bosch pressure sensor that + is DK 828-1005-1-ND .. i2c output, similar range to our current part but + smaller, around $5 at our build quantities. + +2011.12.10 +- the Johanson balun/filter for 70cm use with cc1111 is DK 712-1540-1-ND + uses less PCB area, but lower performance than the discrete approach + +2013.01.04 +- noodling over TM v2.0 .. baro sensor will be hard to handle on cc1111. So, + how about 48-pin version of STM32L, cc110L radio, ms5607 and MMA665X accel. + Move to the faster lipo charger, too. + radio / flash on spi2, sensors on spi1, baro on spi1 alternate pins