Lisa
Lisa ( the Lost Illusions Serendipitous Autopilot) is a new STM32 based range of autopilots designed to run Paparazzi.
The first two members of the family are Lisa/L, a design where the STM32 is associated to a gumstix Overo and Lisa/S, an all-in-one design focusing on space and weight constraints.
Lisa/L
Hardware
Lisa/L is based on the 64 pins STM32F103RE processor featuring 64k of RAM and 512k of FLASH. All the pins are exposed, providing access to the complete set of the STM32 peripherals.
Power Supply
The design features a pair of two amps switching power supply module, one on 5V for external peripherals ( like modems, servos, USB webcams or wifi sticks) and one on 3V3 for the rest of the avionics. A third linear supply is available for providing clean power to inertial sensors.
STM32
In brief, the STM32 features 3 USARTS, 2 SPI, 2 I2C, 1 CAN, a plethora of timers, ADCs and a generic DMA able to serve all of them. On the board, a number of the communication interfaces are level shifted with user selectable voltage to allow interfacing with all kind of peripherals.
Pressure sensors
The board is equipped with a pair of pressure sensors, one absolute to measure altitude and one differential to measure airspeed. The sensors are amplified and low passed before being sampled by a pair of 16 bits ADCs.
The absolute pressure sensor is the freescale MPXh6115 and the differential one is the MPXV5004DP The following plots displays the output of the sensors versus altitude or airspeed
FT2232H
This chip is heart of the communications with the board while developing. It provides JTAG on the STM32 and SERIAL/USB conversion for the Overo console. It is powered by the USB bus and hence unpowered while in flight.
datasheet: URL
mini module used for dev : URL
Gumstix overo
[1] mechanical drawings
The gumstix Overo is a single board computer module featuring a 600Mhz OMAP35 processor. It communicates with the STM32 through SPI, offering throughput up to 48Mbps and served by DMA on both sides. Exposed peripherals comprise two level shifted UARTs and two USB controllers ( one Host and one OTG )
Software
STM32 drivers for Paparazzi
LED : done
SYS_TIME : done
UART : done without DMA, (datalink, telemetry and RC24 working)
PPMout: done (servos)
PPMin: not done, needed for analog radio control and windvane
I2C : done ( motor controllers working )
SPI : done ( IMU, Overo link)
CAN : not done, needed for motor controller and CSC
ADC: not done
STM32 toolchain
Install paparazzi-stm32 package available in the ENAC karmic repository. This toolchains contains gcc, newlib, libstm32, gdb and openocd
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
Work is in progress to offer a pre-compiled cross compilation toolchain.
Lisa/S
More on this new project soon, for now just a CAD rendering to keep your mouth wet.
