3 This is a recording dual-deploy altimeter for high power model rocketry
4 with integrated GPS and telemetry link.
6 These are photos of our current version,
7 which includes an integrated GPS receiver and patch antenna:
9 <a href="v0.2/cimg5164-cropped.jpg"> <img src="v0.2/cimg5164-thumb.jpg"></a>
10 <a href="v0.2/cimg5171-cropped.jpg"> <img src="v0.2/cimg5171-thumb.jpg"></a>
12 And this is a photo of our original board with serial port for off-board GPS,
13 without the big off-board 1000uF cap from the original ejection circuit:
15 <a href="v0.1/loadedpair.jpg"> <img src="v0.1/loadedpair-thumb.jpg"></a>
19 Bdale and Keith both own
20 [BeeLine](http://www.bigredbee.com/BeeLine.htm)
22 [Big Red Bee](http://www.bigredbee.com), and are pretty happy with them.
23 They use a PIC processor and a TI CC1050 transmitter chip, and
24 operate in the ham radio 70cm band.
26 One weekend while attending a conference together, we got to wondering if
27 we couldn't adapt one to use as a downlink for the
28 [AltusMetrum](../AltusMetrum/) altimeter board in addition to direction
29 finding after flight. That caused us to start thinking about other things
30 in the design we might want to tweak, and before long we were working on the
31 design of a new tracker board derived from the BeeLine design.
32 Another friend at the same conference showed us a board he was working on
33 using a different part in the same TI series, that integrated a transceiver
34 and CPU on the same chip.
35 It didn't take us long to realize that with such a part we could combine and
36 simplify things by building a new altimeter with integrated RF link! And
37 after gaining some experience in 2009 with a first version, we realized we
38 always want GPS on board, which lead to our current second generation boards.
44 * Recording altimeter for model rocketry
45 * Supports dual deployment (can fire 2 ejection charges)
46 * 70cm ham-band transceiver for telemetry downlink
47 * Barometric pressure sensor good to 45k feet MSL
48 * 1-axis high-g accelerometer for motor characterization
49 * On-board, integrated GPS receiver
50 * On-board non-volatile memory for flight data storage
51 * USB for power, configuration, and data recovery
52 * Integrated support for LiPo rechargeable batteries
53 * Uses LiPo to fire e-matches, optional support for separate pyro battery
54 * 2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube
56 ### Developer View ###
59 * [TI CC1111F32](http://focus.ti.com/docs/prod/folders/print/cc1111f32.html) Low Power RF System-on-Chip
60 * Sub-1Ghz transceiver
65 * 6 12-bit analog inputs (11 bits with single-ended sensors)
66 * 2 channels of serial I/O
68 * [Atmel AT45DB081D](http://www.atmel.com/dyn/products/product_card.asp?part_id=3819) DataFlash memory
72 * other parts in this Atmel DataFlash series can optionally be used
73 * [SkyTraq](http://www.skytraq.com.tw/) Venus634FLPx GPS receiver
74 * on-board passive patch antenna
75 * U.FL connector with 3.3V DC for optional external amplified antenna
76 * async serial interface
77 * [Freescale MP3H6115A](http://www.freescale.com/webapp/search.partparamdetail.framework?PART_NUMBER=MP3H6115A6U) pressure sensor
78 * [Freescale MMA2202EG](http://www.freescale.com/webapp/search.partparamdetail.framework?PART_NUMBER=MMA2202EG) 50g accelerometer. Can use 40-200g variants!
80 * Written mostly in C with some 8051 assembler
81 * Runs from on-chip flash, uses on-chip RAM, stores flight data to
83 * USB serial emulation for "console" interface
85 * [gEDA](http://www.gpleda.org/) for schematic capture and PCB layout
86 * [SDCC](http://sdcc.sourceforge.net/) compiler and source debugger
88 * The hardware is licensed under the [TAPR](http://www.tapr.org) [Open Hardware License](http://www.tapr.org/ohl.html)
89 * The software is licensed [GPL version 2](http://www.gnu.org/licenses/old-licenses/gpl-2.0.html)
91 ### v0.1 Differences ###
93 * 2.5 x 1 inch board with all parts mounted on one side
94 * 4-pin PicoBlade serial port connector for attachment of external GPS module
95 * USB connector projected approximately 3mm over the edge of the board
96 * Debug connector used 4 IC socket pins on 100 mil centers
97 * no companion board interface
98 * [Microchip 25LC1024](http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en520389) CMOS serial EEPROM instead of DataFlash
101 * [Microchip MCP9700A](http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en027103) discrete temperature sensor
102 * used 1000uF electrolytic capacitor charged to 5V for pyro supply
103 * two LEDs instead of one attached to CPU
105 The elimination of the discrete temperature sensor and second LED were
106 necessary to support the companion board interface added in v0.2.
108 ## [Production History](production) ##
110 ## [Flight Logs](flightlogs) ##
114 * The CC1111F32 is a 36-pin QFN package, which necessitates reflow
115 soldering. Since we needed to reflow solder anyway, and because TI used
116 them in their reference design, we went a little crazy and used 0402
117 passive parts everywhere. That means working under a microscope to
118 place parts! Without an inspection microscope, loading and testing these
119 boards might be impossible.
121 * The addition of on-board GPS in v0.2 means that the total power consumption
122 can exceed the rate at which we draw power from the USB interface,
123 particularly when the GPS is in cold start mode. This means a battery must
124 be attached during operation, and also that the battery will only charge
125 effectively from USB when the board is turned off.
127 * The v0.1 artwork had three issues, two of which required physical rework
128 on each board. All of these issues were fixed in v0.2.
130 * The USB connector footprint was placed wrong, so that the
131 connector hung out over the edge of the board instead of being
133 * We needed chip select on the SPI memory. To fix that, we gave up the
134 ability to put the accelerometer into self-test mode and used that
135 GPIO line to pull chip select on the memory, which required two
136 cuts and two jumpers.
137 * The igniter sense circuits each needed a second resistor to
138 complete the voltage divider so our 3.3V CPU ADC could read the
139 5V ejection voltage. This was fixed by changing two resistor
140 values, and tacking two additional resistors onto the board
141 with jumpers to ground.
145 The hardware design current gEDA files are available from
146 [git.gag.com](http://git.gag.com) in the project
147 [hw/telemetrum](http://git.gag.com/?p=hw/telemetrum;a=summary).
149 Work on the next version proceeds on the master branch, with occasional
150 temporary branches created when Bdale is making some major / speculative
151 change. The 'v0.2' and 'v0.1' branches document what we're actually flying
152 right now on the two respective PCB revisions. The 'ground' branch has a
153 cut-down schematic used to generate the BOM for partially loading v0.1 boards
154 to used on the ground. We call the on-the-ground version 'TeleDongle'.
156 For those who don't have ready access to the gEDA suite, here are pdf snapshots
157 of files in more easily readable form.
159 * These are from the v0.2 branch:
160 * [schematic](v0.2/telemetrum.pdf)
161 * [pcb artwork](v0.2/telemetrum.pcb.pdf)
162 * [bill of materials](v0.2/partslist.csv)
163 * These are as of the working-v0.1 tag:
164 * [schematic](v0.1/telemetrum.pdf)
165 * [pcb artwork](v0.1/telemetrum.pcb.pdf)
166 * [bill of materials](v0.1/telemetrum.bom)
168 Our [AltOS](../AltOS) firmware works well enough that we now routinely fly
169 TeleMetrum with no backup. Rockets with v0.1 boards have exceeded 50g
170 acceleration, been above Mach 1, and reached altitudes greater
171 than 12k feet AGL with great results. Keith's ground station program
172 called ao-view logs telemetry to disk, displays current and max values for
173 key parameters during flight, and even includes voice synthesis
174 during the flight so that our eyes can stay on the rockets! We have post
175 flight analysis software that makes it easy to extract data from the board,
176 analyze it, and even generate KML files for viewing flights in GoogleEarth!
177 More details on the software, including full source code and pre-built packages
178 can be found on the [AltOS](../AltOS) page on this site.
182 As of early February 2010, three prototypes of v0.2 are done and working on
183 the bench. We hope to flight test them shortly, then arrange a production
184 run in time to make TeleMetrum available in assembled and tested form to
185 others in the rocketry hobby who have expressed interest in time for the
188 Because we understand that not everyone uses Linux, we've started discussing
189 the best way to make a cross-platform ground station program for use with
190 [AltOS](../AltOS), perhaps in Java...