Lisa

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Lisa ( the Lost Illusions Serendipitous Autopilot) is a STM32/Overo board designed to run Paparazzi

TODO

  • List of files currently being edited:
    • none
  • Antoine:
    • work with Piotr on connecting the missing wires on the STM
    • JTAG on STM32: ok
    • I2C on STM32:
    • SPI on STM32:
    • USB for gumstix : does 5V need to be switchable ? (to allow reset from the gumstix)
    • Todo's from sheet 3
    • Check's from sheet 5
    • Pressure sensor instruction to gany (redo airspeed computation), so he can finish the schematic for that (or finish it directly in the schematic)
    • Check the routing rules below and add if planned on routing a certain part in a specific way
  • Esden:
    • STM32 spelling and connection check
    • Fix STM32 footprint pad sizes
    • Routing rules that have to be followed
    • Add specification of external pressure sensor ADC
    • howto for STM32 gcc gdb toolchain (blinking LED or similar) (started writing one on openhardwarewiki.org)
  • Gany:
    • Check FT2232 footprint hw/lbr/booz.lbr qfn-64 size & pinout
      • -> Changed pad size from 0.6 x 0.4 to 0.75 x 0.25 and moved pin1 indicator outside the chip.
    • Make sure STM32 can interrupt overo
    • Place components
    • Route board
    • Send for production 4pcb/pcbcard(china)/sunstone

Hardware

The hardware is still in development. The current CAD files are maintained in savannah svn in the paparazzi4/trunk/hw/lisa directory. Software development is done on a Overo/Summit + Olimex STM32-H103 dev board

Lisa proto.jpg

Pressure sensors

The board will be equipped with a pair of pressure sensors, one absolute to measure altitude and one differential to measure airspeed.

Absolute Pressure

The proposed absolute pressure sensor is the freescale MPXh6115 The following plot displays the output of the sensor versus altitude

Absolute pressure.png

Differential Pressure

The proposed differential sensor is the MPXV5004DP

Differential pressure.png

Because of high resolution requirements in the pressure sensor circuit there is an external ADC needed with the following features:

  • 16bit resolution minimum, 20bit would be awesome
  • Two channels (multiplexed or not) each at least 100Hz sampling rate
  • I2C or SPI interface (I2C preferred)
    • We used the MAX11040 as ADC for a meteo payload, some (SPI) code is there. It samples 4 channels simultaneously in 24 bits (less "in real"). Slowest conversion speed is 250.1 samples/second.

Software

STM32 toolchain

You can use the summon-arm-toolchain script to build the required toolchain. For the default values of the Paparazzi Makefile to work, you should set

PREFIX=/opt/stm32/toolchain/arm-elf and LIBSTM32_EN=1

Open Embedded

Open Embedded is the linux distribution used on the overo. You can follow the instructions on gumstix's website to build a complete cross development environment. Paparazzi's Makefile will default to look for it in /overo-oe


Status

Routing Rules

  • 6mil traces/spacings for signals
  • 12mil traces/spacings for power traces (this is min value, otherwise as wide as possible or even planes if possible)
  • 6mil layout grid
  • Layer stacking:
    • Top: Signal + Ground plane
    • Route2: Ground plane(s) (Separate analogue and digital ground)
    • Route15: Power plane(s)
    • Bottom: Signal + Ground plane
  • 0.4mm vias with 0.1mm restring