Revised 4th May 2012
LATEST: Firmware updates released 24th April...
Here is a list of all the HOTT Firmware updates to date as a Google Docs spreadsheet (This is intended to help users decide whether they need to upgrade or not since not all modules are revised as part of a release).
Firmware updates for all the HOTT TXs, RXs and modules are recommended for install prior to any use. Before Firmware release V4 you needed two separate software applications to update Tx, RX and modules, at V4 you can do it via: Firmware_Upgrade_grStudio_Ver-1.9.exe.
All are included in the single zipped download (about 66Mb) available from Graupner's HOTT web Site.
PAY CAREFUL ATTENTION TO THE WIRING AND POWER REQUIREMENTS during firmware update and be sure to follow the steps set out in Graupner's Firmware Update Videos (see my list here).
V4 Firmware Release
This major release allows you to connect two telemetry modules and select between both on the Tx. As an example - I have the Electric Air and GPS modules and have connected these with a Y cable to the Rx. I can now view them both via a quick menu activated using the left-hand mx-16 Tx button. All data from these modules is logged to the MicroSD card in the Tx and can be used to set Speech output warnings from the Tx's headset jack.
Use the following exe file to update all modules, Txs and Rxs to V4: Firmware_Upgrade_grStudio_Ver-1.9.exe. Make sure you update the voice/speech files as well.
Telemetry logs can be played back via an 'Avionics' style interface using options included in the firmwarer update utility: Firmware_Upgrade_grStudio_Ver-1.9.exe. No loal time clock values are currently shown, rather they have to be deduced. This video includes a telemetry excerpt from an Octocopter flight to 100m.
Ignore the HoTT Manager except if you understand a bit of Deutsch and would like to plot all the flight data stored on the microSD card (I can thoroughly recommend trying, the plots are highly revealing and can help spot system issues prior to any mishaps!).
V4 Known Issue: Incorrect reading of LiPo Cell H1 VoltageAs of 14th March 2012 Graupner UK have acknowledged an issue with the incorrect (-0.1v) reading of LiPo cell H1 (Main Power Battery 2). Apparently this may be down to an assumption that batteries would be connected in series as opposed to parallel. WORKAROUND: In the case of my own 2 X 4S octocopter LiPos this means that I have to set my cell voltage alarms 0.1V lower than if all cells were being read correctly (because the alarm works using the lowest cell reading) So whereas I used to set my alarm to go off at 3.7V I now need to set it to 3.6V and keep an eye on the other cell voltages visually. Graupner Germany are aware of the issue and will look to fix this in a future firmware release.