# TeleMetrum
-<p>
-A quick update as of 25 December 2008.
-The circuit board artwork is out for fab!
-</p>
-<p>
-A quick update as of 16 December 2008.
-The ARM7-based 'AltusMetrum' design has been shelved indefinitely.
-Working with Keith Packard, I recently embarked on a complete redesign based on the TI cc1111.
-We got there by deciding we need a low-power RF beacon for post-landing direction finding, learning
-of the existence of this part, then realizing that we could radically simplify things by using it
-as the basis for a completely new avionics design.
-The cc1111 integrates a full 70cm transceiver, 8051 processing core, and peripherals on one chip.
-We add to that a barometric sensor, temperature sensor, accelerometer, eeprom memory, and full LiPo
-battery support powered by a USB interface also used for configuration and post-flight data extraction.
-It looks like we can get all the features we want on a single board for less than the price of most
-commercial altimeter boards, with the only downside being dramatically reduced processing power.
-We have a complete schematic and a first pass PCB layout that is currently
-under review and improvement prior to sending out for raw boards.
-</p>
-<p>
-See the hw/telemetrum tree in our
-<a href="http://git.gag.com">public git repository</a>
-for the current state of the gEDA design files.
-</p>
-<p>
-We hope to be turning on boards and writing firmware over the
-Christmas / New Years holiday season.
-Stay tuned!
-</p>
-<hr>
+This is a recording altimeter for high power model rocketry with integrated
+telemetry link.
+
+## Motivation ##
+
+Bdale and Keith both own
+[BeeLine](http://www.bigredbee.com/BeeLine.htm)
+trackers from
+[Big Red Bee](http://www.bigredbee.com), and are pretty happy with them.
+They use a PIC processor and a TI Chipcon cc1050 transmitter chip, and
+operate in the ham radio 70cm band.
+
+One weekend while attending a conference together, We got to wondering if
+we couldn't adapt one to use as a downlink for the
+[AltusMetrum](../AltusMetrum/) altimeter board in addition to direction
+finding after flight. That caused us to start thinking about other things
+in the design we might want to tweak, and before long we were working on the
+design of a new tracker board derived from the BeeLine design.
+Another friend at the same conference showed us a board he was working on
+using a different part in the same TI series, that integrated a transceiver
+and CPU on the same chip.
+It didn't take us long to realize that with such a part we could combine and
+simplify things by building a new altimeter with integrated RF link!
+
+## Features ##
+
+### User View ###
+
+* Recording altimeter for model rocketry
+* Supports dual deployment (can fire 2 ejection charges)
+* 70cm ham-band transceiver for telemetry downlink
+* Primary operations based on pressure sensor
+* Temperature sensor
+* 1-axis high-g accelerometer for motor characterization
+* On-board non-volatile memory for flight data storage
+* Serial port for attachment of GPS module
+* USB for power, configuration, and data recovery
+* Integrated support for LiPo rechargeable batteries
+* Designed to fit 29mm airframe tube
+
+### Developer View ###
+
+* TI CC1111F32 Low Power RF System-on-Chip
+ * Sub-1Ghz transceiver
+ * 8051 MCU
+ * 32k Flash
+ * 4k RAM
+ * USB 2.0
+ * analog, digital, and serial I/O
+* Microchip 25LC1024 CMOS serial EEPROM
+ * 128k x 8
+ * SPI interface
+* Various Sensors
+ * Freescale MP3H6115A pressure sensor
+ * Freescale MMA2202 50g accelerometer
+ * Microchip MCP9700A temperature sensor
+* Software Features
+ * Written mostly in C with some 8051 assembler
+ * Runs from on-chip flash, uses on-chip RAM, stores flight data to
+ serial EEPROM chip
+ * USB serial emulation for "console" interface
+ * Uses the SDCC compiler and FreeRTOS
+* Licenses
+ * The hardware is licensed under the TAPR OHL
+ * The software is licensed GPL version 2
+
+## Problems ##
+
+* The CC1111F32 is a 36-pin QFN package, which necessitates reflow soldering.
+
+* Since we needed to reflow solder anyway, and because TI used them in their
+ reference design, we went a little crazy and used 0402 passive parts
+ everywhere. That means working under a microscope to place parts!
+
+## Artifacts ##
+
+The hardware design current gEDA files are available from
+[git.gag.com](git.gag.com).
+
+As of 1 January 2009, the parts and stencil for the v0.1 have arrived, and
+we're waiting for the raw PC boards! Stay tuned for updates, and note that
+Bdale will be giving an update in his session at Linux Conference Australia
+in late January...
projects / web / altusmetrum / commitdiff