Finally! This firmware update has been in the works for a long time, and includes big improvements again for auto bulb ramping with the Timelapse+. It's been tested extensively and includes many bug fixes as well.
New auto bulb ramping algorithm for more accurate tracking
The new algorithm is based on PID control and results and much better tracking of the exposure through the day-to-night transition while still ignoring momentary changes. Last year the auto bramp algorithm was updated to have the Timelapse+ control the rate of change rather than the exposure value directly. This made for much smoother results and made possible the the "night target" set point as well. However, it was prone to get a bit dark during the transition from day to night. This new algorithm keeps the rate of change method of control, but does a much better job of tracking with the change of light and is more tunable. More details, tuning instructions, source code, and a simulation chart can be found here: http://firmware.timelapseplus.com/sunset
PC-sync cable feedback + auto calibration
The Timelapse+ can use the camera's flash sync for reducing flicker and auto-calibrating the camera's timing parameters. Set Settings->Auxiliary->AUX Port to 'PC Sync In' to enable. The result is less flicker, faster shutter speeds in bulb mode (up to 1/60th for Canon), and auto-configuration of timing parameters. Just connect the camera via USB and it will prompt to auto configure if it hasn't been done already for that camera.
Remembers camera-specific settings for multiple cameras
Easily switch between cameras without having to change camera-specific settings when using USB. Additionally, the Timelapse+ will automatically update the Camera Make setting according to the connected camera, so it's easy to switch between Canon and Nikon while keeping the optimal settings for each. Everything in Settings->Camera is linked to a profile for the currently connected camera. Changing those settings without a camera connected will change the defaults for new camera -- preconfigured cameras will always use the saved profile.
More videos are in the works -- thanks for your patience!