# TeleMetrum History

## v0.1 ##

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)

## 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)

## 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)

## v1.1 ##

<a href="v1.1/telemetrum-v1.1-thside.jpg"> <img src="v1.1/telemetrum-v1.1-thside-thumb.jpg"></a>
<a href="v1.1/telemetrum-v1.1-smtside.jpg"> <img src="v1.1/telemetrum-v1.1-smtside-thumb.jpg"></a>

For those who don't have ready access to the gEDA suite, here are pdf snapshots
of the files for Production PCB version 1.1 in more easily readable form.  

* [schematic](v1.1/telemetrum.pdf)
* [pcb artwork](v1.1/telemetrum.pcb.pdf)
* [bill of materials](v1.1/partslist.csv)

## v1.2 ##

Our current production version.