Pecan Pico 11

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A319
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Pecan Pico 11

Postby A319 » Fri Nov 23, 2018 2:11 am

Good morning,

A while ago I've written something about the Pecan project which was at it's 8th version back then. Since then it has developed to version 11a and found some participants like FXcoder, who helps me out very much in developing the software with ChibiOS and keeping contact with Giovanni.

The Pecan Pico originated as APRS tracker. APRS is a amateur radio based network to report GPS positions in defined intervals by radio. Since FXcoder helped me out figuring out how to abuse the GFSK transceiver for AFSK receiption as well, the device became a real allrounder. Even though the network is mainly used for GPS position transmissions, it can also be used to transmit binary data such as telemetry or pictures.

The newest design (pp11a) uses the brand new STM32L4R9 as this microcontroller as way more memory (640kB) than the so far used STM32F413. That amount is necessary to buffer the pictures we are going to capture with the DCMI interface. XGA-sized pictures can be around 150kB which should leave plenty of memory left for other stuff.

The pictures get transmitted and then picked up by the APRS network and processed on a server written by me.
Telemetry: http://www.wlankabel.com/telemetry.php?call=VK2GJ-2
Pictures: http://www.wlankabel.com/images.php?cal ... ge=2592000 (loading takes some time)

The current data on the server is based on the older PP10b design while we haven't ported the code to the new tracker yet. While ChibiOS is lacking support like DMA at the moment for the new STM32L4R9, I haven't been able to put DCMI into use, but I hope I can give a follow-up at some time.

Here are some features of the tracker
- 2 transceivers (for the 145MHz and for the 435MHz band)
- GPS receiver (ublox ZOE-M8, supports Galileo and GLONASS too)
- External memory available (64Mbit)
- MicroSD card available (dedicated SPI)
- Compatible camera chips (OV9655, OV2640, OV5640 as far I know)
- 128kB-EEPROM available for storing configurations
- Powered by either single LiPO, USB or by solar MPPT regulator (LiPO can be charged by USB or solar)
- Internal airpressure/humidity/temperature sensor available (BME280)
- External ports (USB, SPI, UART, I2C)

Even though I'm often asked if I sell those boards, I'm unable to do so while those boards are all handcrafted and it takes a friend and me around one day to build a single unit with our BBQ soldering technique (aka. reflow soldering). Here's a video of it:

https://www.youtube.com/watch?v=EEOKalrRqYU&feature=youtu.be

This board is wider so it may fit into a sliding case. The excess can be broken off if not needed. This board has no GPS receiver while we were still waiting for that component to arrive at that time. It also has no GPS antenna fitted, because an external antenna can be connected by the IPEX connector.

IMG_20181112_120428457(1).jpg
IMG_20181112_120407712(1).jpg


Our smallest component (a power switch) is literally a nightmare to solder. it has a pitch of 0.35mm. It took us 2 hours to fix solder errors with those components. But therefore we got more experience with those parts.

IMG_20181110_182216664.jpg


Sven / DL7AD

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