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.

2011.10.27
- looks like DK 644-1056-1-ND may be a good 32mhz rock choice for the cc1120

2011.06.11
- thinking about what a second-generation TeleMetrum might be like

	- board width sized to fit inside 38mm coupler .. say, 32mm wide

	- ARM cpu w/USB interface

		- STM32L151RBT6		DK 497-11193-ND		4.81 @ q100
			- 32Mhz Cortex M3
			- 128kx8 flash, 16kx8 RAM, 4kx8 EEPROM
			- 64-LQFP with 51 i/o pins (48 or 100 pin variants)
			- 20 x 12b ADC, 2 x 12b DAC
			- 2 spi, 2 i2c, 3 usart, usb
			- 1.8 or 3.3V, very low power
			- needs 1-24 Mhz crystal

	- cc1120 transceiver
		- SPI target with improved performance over cc1111
		- QFN-32
		- 50mA typical power drain TX in 70cm band, 22mA receive
		- wants 32 Mhz crystal
		- maybe with a switched amplifier and preamp?
		- can be used with the CC1190 on the 900mhz band (not useful)

	- more than 2 pyro channels

		- 10 screws are 25.86mm wide
		- 12 screws are 30.94mm wide 

		- a better plan would be to put two screw strips back to
		  back aligned with the major axis of the board, so that
		  wires come out either side instead of to the rear?

		- definitely want to support use of separate pyro battery,
		  need to think about the best way to do that.

	- GPS
		can we get high dynamic firmware from Skytraq, or
		do we need to change to a different vendor?

	- baro
		MS5607 .. I2C or SPI, 10 to 1200 mbar, 1uA, DFN-8'ish

	- accel
	    1-axis high-G for motor characterization
		MMA6556KWR2 .. SPI, 1 axis, +-120g, 7mA max, QFN-16
	    3-axis medium-G for orientation .. all are I2C or SPI
		Bosch BMA250	16g, 8hz-1khz, 32lsb/g	    3.07 q100
		ST LIS331HH	24g, 50hz-1khz, 3mg/digit   4.89 q100
		Analog ADXL345	16g, 6.25hz-3.2khz, 32lsb/g 5.88 q100
			
	- 3-axis gyro 
		ST L3G3250A	2000dps, analog out (not really available?)
		ST L3G4200D	2000dps, I2C or SPI, 1 ADC + mux
		ITG-3200	2000dps, I2C only, 3 ADCs
		ITG-3050	2000dps, I2C only, 3 ADCs, with low noise
				and better sensitivity than the 3200?

		Invensense also has an IMU-3000 that is like the above gyro
		parts but can have a 3-axis accel as i2c slave and will do
		the navigation computing.  $12 vs $10 each.  The MPU-6000/6050
		is the holy grail, 3-axis gyro and accel on one chip that
		outputs nav solutions... but it's not shipping yet.

2011.06.30
- keithp points out that in the STM32L151 family, only the 100 pin versions
  expose the second SPI port.

	STM32L151VBT6 is DK 497-11195-ND, $5.38 @ q100
		- 32Mhz Cortex M3
		- 128kx8 flash, 16kx8 RAM, 4kx8 EEPROM
		- 100-LQFP (14x14mm) with 83 i/o pins (48 or 64 pin variants)
		- 24 x 12b ADC, 2 x 12b DAC
		- 2 spi, 2 i2c, 3 usart, usb
		- 1.8 or 3.3V, very low power

2011.11.23
- decisions based on IRC conversation with keithp
	- GPS on usart3 PC10/11 doesn't conflict with the serial bootloader
	- pick either usart1 or usart2 on PD5/6 or PA9/10 for bootloader
	- flash and companion can share an SPI, sensors need dedicated SPI
	- use 3 screws for v_pyro, either jumper to tie to v_lipo or attach
	  separate battery .. plan to ship boards with the jumper installed
	- 2 screws for power switch
	- 6 pyro channels, 2 screws per channel = 12 screws
	- 2-pin 2mm box connector for primary lipo
	- same lipo charger as on lipocharger, set for 500ma charge rate
	- include a screw attached to ground, easy attach for magnetic switch
	- that makes 18 screws, use two 9's back to back

	- silicon	
		- STM32L151VBT6 Cortex-M3 SOC
		- CC1120 digital radio				spi2
		- W25Q64BVZEIG 64Mbit flash			spi2

	- sensors
		- Freescale MMA6556KWR2 120g 1-axis accel	spi1
		- Bosch BMA250 16g 3-axis accel			spi1
		- Meas Spec MS5607 baro sensor			spi1
		- ITG-3200 2000 deg/sec 3-axis gyro		i2c1
		- SkyTraq Venus 638 GPS				usart3

	- companion port					spi2
								i2c2
						bootloader intf	usart1
								usart2