## Future Plans ##
-TeleMetrum v1.1 meets all of our expectations, except for one mis-placed
-trace also present in v1.0. The error makes use of a separate pyro battery
-less trivial than intended. We'll fix that for a future production run.
+TeleMetrum v1.2 is back from our assembler and the first batch are being
+prepared for sale, hopefully by Christmas day. The significant user-visible
+change is that we've moved to a 70g accelerometer by default, due to poor
+availability of the part we previously used due to damage to the Freescale
+facility in Sendai caused by the Japan earthquake / tsunami. Full details
+will be posted here when they're available to order.
## Problems ##
be attached during operation, and also that the battery will only charge
effectively from USB when the board is turned off.
-## History ##
+## [History of TeleMetrum](history) ##
-### v1.0 ###
-
-These are photos of our third version, which was the basis of our first
-production build. These were sold between April and December 2010, and
-performed very well.
-
-<a href="v1.0/cimg5972-crop.jpg"> <img src="v1.0/cimg5972-thumb.jpg"></a>
-<a href="v1.0/cimg5974-crop.jpg"> <img src="v1.0/cimg5974-thumb.jpg"></a>
-
-The differences between v1.0 and v1.1 were small:
-
-* different flash memory part due to supplier availability problems
-* updated reset circuit to improve reliability at temperature extremes
-* changed the GPS antenna footprint to eliminate the large through-hole
- originally intended for use with a passive patch
-* irq line eliminated from the companion port
-* an additional resistor divider added to allow sampling the 5V supply
-
-The schematics and PCB artwork for this version are on the v1.0 branch in
-our git repository, here are pdf copies for easy reference:
-
-* [schematic](v1.0/telemetrum.pdf)
-* [pcb artwork](v1.0/telemetrum.pcb.pdf)
-* [bill of materials](v1.0/partslist.csv)
-
-
-### v0.2 ###
-
-These are photos of our second version, which included the integrated Venus
-GPS receiver, but with a passive patch antenna that turned out to have
-disappointing performance due to our many PCB geometry constraints. It also
-used a voltage regulator with less capacity which we felt was marginal for
-supporting the companion boards we have planned:
-
-<a href="v0.2/cimg5164-cropped.jpg"> <img src="v0.2/cimg5164-thumb.jpg"></a>
-<a href="v0.2/cimg5171-cropped.jpg"> <img src="v0.2/cimg5171-thumb.jpg"></a>
-
-Other than cleaning up the silkscreen, the differences between v0.2 and
-v1.0 boards were really quite small:
-
-* 100ma LDO regulator instead of the current 150ma part
-* no C38 footprint
-* different value for C36 reset capacitor
-
-The schematics and PCB artwork for this version are on the v0.2 branch in
-our git repository, here are pdf copies for easy reference:
-
- * [schematic](v0.2/telemetrum.pdf)
- * [pcb artwork](v0.2/telemetrum.pcb.pdf)
- * [bill of materials](v0.2/partslist.csv)
-
-### v0.1 ###
-
-And this is a photo of our original board with serial port for off-board GPS,
-without the big off-board 1000uF cap from the original ejection circuit:
-
-<a href="v0.1/loadedpair.jpg"> <img src="v0.1/loadedpair-thumb.jpg"></a>
-
-The differences between v0.1 and later boards were substantial:
-
-* 2.5 x 1 inch board with all parts mounted on one side
-* 4-pin PicoBlade serial port connector for attachment of external GPS module
-* USB connector projected approximately 3mm over the edge of the board
-* Debug connector used 4 IC socket pins on 100 mil centers
-* no companion board interface
-* 50ma LDO regulator on early boards, later boards used a 100ma part
-* [Microchip 25LC1024](http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en520389) CMOS serial EEPROM instead of DataFlash
- * 128k x 8
- * SPI interface
-* [Microchip MCP9700A](http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en027103) discrete temperature sensor
-* used 1000uF electrolytic capacitor charged to 5V for pyro supply
-* two LEDs instead of one attached to CPU
-
-The elimination of the discrete temperature sensor and second LED were
-necessary to support the companion board interface added in v0.2.
-
-The v0.1 artwork had three issues, two of which required physical rework
-on each board. All of these issues were fixed in v0.2.
-
-* The USB connector footprint was placed wrong, so that the
- connector hung out over the edge of the board instead of being
- flush.
-* We needed chip select on the SPI memory. To fix that, we gave up the
- ability to put the accelerometer into self-test mode and used that
- GPIO line to pull chip select on the memory, which required two
- cuts and two jumpers.
-* The igniter sense circuits each needed a second resistor to
- complete the voltage divider so our 3.3V CPU ADC could read the
- 5V ejection voltage. This was fixed by changing two resistor
- values, and tacking two additional resistors onto the board
- with jumpers to ground.
-
-The schematics and PCB artwork for this version as of the working-v0.1 tag
-are available here are pdf copies for easy reference:
-
- * [schematic](v0.1/telemetrum.pdf)
- * [pcb artwork](v0.1/telemetrum.pcb.pdf)
- * [bill of materials](v0.1/telemetrum.bom)
projects / web / altusmetrum / blobdiff