First a little history. The 1402 is a 4x4 cube designed for a high end motor coach that contains a vehicle power converter, a backplane, a LON network to serial interface card, and an embedded 286 x86 PC running DOS 6.22. It is used to display the vehicle’s status and operating conditions on the vehicle’s various display screens.
The problem is that the PCs in these units have exceeded EOL (end of life) and are now beginning to fail. Of course this was the only part of the system that was purchased from a third party vendor and, not only is it no longer available, the company that made it will not even acknowledge its existence. So we designed an interface board to allow a Raspberry PII board to be plugged into its place.
The program running on the unit consists of an ASCII serial interface that does some minor "hello there" handshaking, then receives 64 variables and/or a "change page" command from the LON interface board. The active variables are mapped to 1 of 5 graphical pages that are scrolled when a "change page" command is received. Each page displays and updates its data until the next "change page" command is received at which time the next page in sequence is loaded.
As a first step, we would like to try using Linux running "DOSBox". This may allowing us to run the existing program without change to alleviate the immediate crisis. We do have a semi-functional version that was written by someone else using Windows IOT, but he quit half way thru the process. However he did advance to the point that the serial communication was working, so at least we know that the communication between the LON interface and the Raspberry PII is possible. The question will be whether the DOSBox serial driver functions correctly for our needs.
Another issue will be to assign a soft Linux shutdown to one of the unused Raspberry PII I/O pins, so we can try to mitigate the SD card corruption issue that can occur during un-scheduled power offs of the unit. We will be adding a loss of power detection circuit to the adapter board to generate the needed signal. We will need Linux coding to support this running in the background.
Display generation will be another issue. Ideally we would like to get outputs on both the composite and HDMI outputs. We need composite because most of the vehicles have old school composite video input backup monitors in their dashes. These are used to display the data when the vehicle is parked and the backup camera when in motion. Switching common signals is much more reliable then converting them in the vehicle environment. These monitors were made custom for this original purpose. Replacing them requires major rework of the dash and camera system in most cases.
We also need HDMI because most of the vehicles that have been forced into updating and have monitors with HDMI inputs. Switching, as opposed to converting, is still a better solution for these monitors too. Note: Most owners also like to display the coach data on their TVs as well as the dash display.
The second phase would be to duplicate the functionality of the DOS program in Linux and run it natively on the Raspberry PII.
The third phase would be to include the ability to view the coach data on hand held devices (phones etc.) using the local blue tooth or the Ethernet connection.
The final phase would be to add limited I/O control to the hand held devices by adding a second LON interface to the cube and sending out network commands. This would require the additional complication of having to program the second LON interface.
This project will be paid on a 1099 basis at $12.50/hour.
Contact information:
Susan Gabel
(610) 682-9764
Email: susangabel@techlon.com
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