From: Bdale Garbee Date: Thu, 1 Jan 2009 21:15:46 +0000 (-0700) Subject: flesh this out more X-Git-Url: https://git.gag.com/?a=commitdiff_plain;h=ce09b7596edbc0103d77beb7236a36d36370de57;p=web%2Faltusmetrum flesh this out more --- diff --git a/TeleMetrum/index.mdwn b/TeleMetrum/index.mdwn index 8d2a4e5..556ae98 100644 --- a/TeleMetrum/index.mdwn +++ b/TeleMetrum/index.mdwn @@ -1,32 +1,85 @@ # TeleMetrum -

-A quick update as of 25 December 2008. -The circuit board artwork is out for fab! -

-

-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. -

-

-See the hw/telemetrum tree in our -public git repository -for the current state of the gEDA design files. -

-

-We hope to be turning on boards and writing firmware over the -Christmas / New Years holiday season. -Stay tuned! -

-
+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...