Since I'm building a FPV (first person video) based quadcopter, I need something that will display the copters telemetry a display or goggles. I'm going with the Minim OSD v1.1. I like that it is a mini Arduino (328P) based on-screen display board.
There are a lot of little details you need to think about when taking a project from PoC (proof-of-concept) to production. Most projects today have some form of onboard microprocessor and require you to flash your custom bootloader and/or program code onto it at some point. There are many ways this can be accomplished but the most common method is using an ICP (in-circuit programmer) connected to a 6-pin ICP header somewhere on the PCB.
Just found out about the Video Experimenter shield (via hackaday) created by Nootropic Design. I’ve been looking for something like this for my screen masking controller project. One has been ordered and will report back once I make some progress getting it tied into the masking controller (which has now been converted to an Arduino project as well).
Here are a few details on the shield, peep the video below for the full effect:
- Overlay text and graphics onto a video signal from a camera, DVR, DVD player, VCR or any other source of composite video.
- Capture low-res video image frames for display or video processing. Give your Arduino the gift of sight!
- Perform object detection for computer vision projects.
- Decode closed captioning or XDS (extended data services) data embedded in television broadcasts.
- Works with NTSC (North America) or PAL (rest of the world) television standards.
(This product is now available for purchase)
While it was possible to use an Arduino duemilanove (Atmel 328 chipset) for this project (See Part 1), I was really limited due to the 2K of RAM. It was fun trying to optimize code to get things to run in that amount of memory, however, it caused me to not be able to expand on functionality and features. I have upgraded the project to an Arduino MEGA (Atmel 1280 chipset). This platform gives me up to 8K of RAM — which should be more than enough memory (famous last words).
A lot of people have asked me to explain what exactly I’m doing with the Arduino. It’s pretty simple. First, I’m using a RS232 shield (not shown) to capture RS232 commands from the Russound Controller. When a key is pressed on the Russound keypads I read the RS232 data and either ignore or react to the events. Currently, I’m looking for +, -, Next, Previous, Play/Pause, Menu events. I plan on using the Menu button to offer deeper content browsing menus (need to sniff the RS232 or wait for Russound to publish protocol). The + & – buttons will allow to scroll playlists and the rest of the transport buttons are self explanatory.
// Example RNET Next Track Event: F0 0 7D 7 0 0 7F 5 2 1 0 2 1 0 E 0 0 1 7 0 1 2A F7 |
Since the Sonos is a uPnP based system there is no IR or way to traditionally control it. Everything needs to be done via HTTP calls. I’m using an Ethernet Shield to translate the RS232 events to uPnP messages. The biggest challenge has been parsing the huge amounts of VERY VERBOSE SOAP-based notification messages. I parse the data real time, looking for strings that I want to store (things like playstate and metadata).
To make matters worse, Sonos is URL encoding XML data inside of an XML structure. So writing a simple XML parser is not possible. You have to look for things like &lt; for a less-than bracket (<). There were times I wanted to scrap the whole project because of this due to the limited RAM and string utilities — it really makes things a lot harder to deal with.
// Example of nested URL encoded XML: <Event xmlns="urn:schemas-upnp-org:metadata-1- 0/AVT/" xmlns:r="urn:schemas-rinconnetworks-com:metadata-10/"> <InstanceID val="0"><TransportState val="PLAYING"/ ... |
When I get a notification message, I package it up into the RNET protocol and send it back into the Russound controller, which gets displayed on the keypads and automation systems that use that data (like Myro:Home which is connected to a HAI OmniPro II). Since uPnP uses a subscription model, I also need to keep subscription expiration timing so I can renew the subscription. It’s basically a client (outgoing to the Sonos to send subscription requests) and a server (to receive incoming notification events from Sonos). Then I have to deal with all the HTTP issues, like if it fails to renew or I have connection issues, I have to clean up and start the connection process all over again.
This project is now code complete and any new features will be made in a future revision. I plan on creating a custom PCB — any interest?
If you have any questions or comments feel free to post them in the comments section below!
(This product is now available for purchase)
Also, check out PART 2, which goes into more details >
Here’s a sneak peak at my latest project — the RNET to Sonos Bridge. All coded using an Arduino and Ethernet Shield. What this little device allows you to do is control a Sonos device using any Russound whole house audio system that supports RNET sources. It allows next, previous, play, pause and I’m working on playlist access and support. Current track metadata gets sent to these keypads as a multi-field message.
I’m pretty much code complete but I’m running into a few memory issues… The Arduino only has <2K of available RAM that I can work with. I have an Arduino Mega (which offers 8K) on order to see if that solves things. I think I can still optimize my code to make it work with the 328.
I’ll post more when I get it 100% stable.
Update: Got it working! With about 500bytes left of RAM on the 328 chipset… this was a fun little project. Below is a video:
Also running on E6 Color Keypads:
I’ve been testing an Olimex PIC-WEB Ethernet Web PIC Development Board for a bit now and this little board comes in handy for projects that need quick web access. The PIC-WEB offers a very small but powerful webserver based on the PIC 18F452. The development board has everything you need to serve web pages with 1 megabit storage on board! I also have an Arduino with an eShield which I will be testing next!
Available from SparkFun Eletronics.